• Tag Archives Boiler
  • The 2019 Boiler Report – Reading Between The Lines

    Trade Journals are currently publishing the Annual Boiler Report for 2019. It is lengthy, detailed and provides tradesmen insight into both Industry Development and Regulatory Trends. Content and commentary is typically provided by Sales, Marketing and Product Managers of the various Boiler Manufacturers.

    Of particular note is the trend toward larger, commercial grade condensing gas systems and focus on advanced fire-tube heat exchanger designs. These new products are also being highly sensor-instrumented with interface optioning to IoT and Building Energy Management Systems. Further, industry focus appears to be upon gas-fired market development with no direct mention of oil throughout. However the inferences within the specific participant content need extraction and commentary.

    Industry Regulation of the Boiler Industry via DOE AFUE Requirements both current and projected are significant, well defined and discussed. Again the focus is wholly upon the Gas Appliance Market and the incremental impacts between 2020 and 2023, as interpreted. DOE has yet to become specific on Commercial Boiler AFUE’s and implementation points, but “residential gas boilers must have an AFUE of 90 percent or greater in all applications”. The new boiler efficiency standard will become effective in 2021.

    In this new world there will be effectively little gas-fired cast-iron in particular and with predictable consequence. This point is well reinforced in the report by comment of a major boiler manufacturer that “many customers are still looking for the long-term dependability of cast iron. When you really factor in everything from the cost of the boiler, installation cost, maintenance costs and life expectancies, cast iron is still a very sound choice”. Weil-McLain also weighs in: “Our legacy cast-iron lines have set the standard for performance and longevity with our high-efficiency lines continuing to lead the industry in innovation, operating fuel efficiency and ease of installation and maintenance”. Are we “throwing out the baby with the bath water”, to employ the old adage? The effect is to supplant in our view with a potentially less durable, yet more sophisticated and costlier product. The marketplace will ultimately decide.

    “Products that can connect to a smart device and be monitored remotely is a heightened demand in the heating industry.” This is self-evident in the commercial sector and upscale housing where loss prevention can be outweighed by the added technology costs. Even in our personal experience the Wi-Fi Thermostat has widely infiltrated our residential consumer base. Witness a mid-winter night call from our customer in Pearl Harbor, Hawaii that his N.H. ski cottage had a temperature drop issue ….. using his cell phone and Wi-Fi Thermostat. To another we provided our oil boiler system with temperature sensor provisions to winter freeze-inhibit his outdoor wood boiler while he annually holidayed with family in the south. Consumers are becoming a savvy bunch and consequentially arrive at cost-effective system application solutions. This is well reinforced by a Boiler Report commentary that “adoption of new technology takes longer in the heating industry than in many other industries” ….. excepting “cool” customers?

    Technological boiler design inception is being tempered by the critical shortage of skilled trade personnel. “A large population of contractors are starting to reach retirement age and a much younger group is starting to enter the field.” Integrating gas boiler system elements such as hydronic expansion, circulation (internal and external), zone and system controls into their products is widespread in reducing installed costs and installation times. A major manufacturer states “we have opted to expotentially increase the number of training events both here at our facility and at locations throughout the country”. Our personal 60-plus year observation: residential heating installers in particular have never kept up with industry technology and it promises to not get better ….. technology far outpaces its proper application in the trades.

    Interwoven in the Boiler Report is commentary on “ours vs. theirs” offerings by boiler types, and most specifically the gas “Comb-Boilers” and their limitations. “One of the major drawbacks of a combination boiler is that you can only use one of the functions at a time, which can cause potentially uncomfortable situation for a homeowner.” This provider further advises of his “revolutionary design that allows for true simultaneous domestic and heating functionality”. This and other discussion support our field observation that misapplication of boiler designs to applications is evident in both gas and oil heating. Contemporary residential distribution piping practices in particular emphasize aesthetics vs. technical correctness. Witness the recent trade supplier “photo contests” to provide the prettiest workmanship installations. Nothing new ….. technology is misunderstood and hence misapplied.

    A common boiler provider’s theme is “design-for-manufacture” as we manufacturing engineers refer to obtain “economies-of-scale”. “We have components prebuilt within the factory.” The particular comment of “parts standardization across all manufacturer lines” may aid the individual boiler supplier, but there are very few common sensory and control parts in the emerging condensing gas industry in total. A Gas Heating Serviceman in a rural area (typically LP-Propane) cannot possibly stock nor have ready Trade Distributor access to boiler manufacturer-specific service parts. The customer is too often left cold ….. and angry! In fact it is difficult to find propane service by other than a Factory Technician, if that is even available. In the maturation process, the industry as a whole must address technical standardization and service issues ….. or stall.

    Underlying all these points noted from The 2019 Boiler Report is a more profound one ….. addressing the entire hydronic system installation methodology from a total system efficiency perspective. Other than providing a “Boiler Installation Guide” with generic piping and wiring installation diagrams therein, the residential heating industry ignores aggregate system efficiencies. The boiler industry sells components ….. not systems. The integration of distribution and control elements into new condensing gas offerings is commendable, yet a small beginning. Emergence of efficiency-optimized boiler/distribution gas or oil heating appliances at minimum are required. The system elements are there, but their evolution into particularly residential heating appliances will be painfully and historically slow …..

     

     


  • WHAT IS A GRAVITY HEATING SYSTEM? – Gravity Convection Heating Revisited

    The three (3) basic elements of hydronic heating are heat generation (boiler), distribution of energy (pumps) and conversion to area warmth (radiation). Of these hydronic distribution is typically the least understood, generally misapplied and needs revisiting.

    What is a Gravity Heating System? A century ago all water-based hydronic heating (hot water and steam) employed the natural gravity attributes of heated water and water vapor (steam) to distribute energy. NO DISTRIBUTION ENERGY WAS REQUIRED! These were effectively single-zone systems that could only be modulated by varying the energy input of the boiler and the radiation outputs using register dampers or steam radiator vents, respectively. Natural (gravity) convection of heated water underlies all hydronic distribution, yet is not considered in contemporary practice. So, check valving is installed to negate its less desired effects.

    The introduction of electric circulation pumps in the 1920’s enabled forced hot water heating (FHW) and changed hydronics forever. Gone was the large, pitched piping and radiators, replaced with zoned heating and finned radiation. The heating market never looked back, and justifiably so. Underlying this however remained the natural gravity convection effect that had to be controlled using check valving as noted within the system.

    Early electric circulation pumps (circulators) were large, power consumptive and constructed of discrete components, i.e. motor to coupling to pump. We “old-timers” have vivid memories of failed couplings of varied types, seized and leaking pumps and smoked motors. The advent of wet-rotor circulators was like manna from heaven, reducing circulator issues with greater longevity and reduced power consumption benefits.

    Now the evolution and introduction of particularly Delta-T (differential temperature sensing) ECM Circulators projects hydronic distribution management to an entirely new level. Integral instrumentation and operational data display of these circulators provide us with finite attribute identification and application control.

    The focus of our work has been to optimize this hidden contribution of natural gravity convection as both a distribution energy saver and a selective fail-mode feature in hydronic heating. As such the Delta-T ECM Circulator has been the crucial tool in our development of our “Delta-T ECM Hydronic Heating Appliance”. We claim optimization of natural gravity convection within our boiler, near-boiler distribution piping and distribution energy requirements using a dedicated Delta-T ECM Appliance Circulator. Citing an automotive analogy, we refer to it as “putting an Automatic Transmission on a Boiler™”. This intelligent, variable speed circulator is effectively a hydronic CVT (Continuously Variable-Speed Transmission) in practice.

    Let’s go back to that old gravity hot water heating system of a century ago. By comparison, contemporary hydronic heating systems have smaller piping with multiple zones for heating flexibility. The old “gravities” necessarily used high-mass cast-iron boilers to modulate heating supply, otherwise control was particularly difficult when using solid fuel firing as with wood or coal. With generous distribution piping sizes and radiation elements gravity convection worked fairly well, and with NO distribution power requirements!

    Properly pipe a contemporary FHW system using a dedicated “Delta-T Mode” system circulator with complimentary low-energy ball-type zone valves vs. flow-checks yields great results! Transpose this configuration onto the old gravity system layout and you functionally emulate its performance as in the following figures.

    The advantage is in using natural gravity circulation in this contemporary upgrade. Today we have somehow lost the trade skills of enhancing gravity convection. No consideration is given to pitching, compacting and minimizing distribution piping in particular. Additional gains are available in radiation layout by using properly sized and configured series and/or split radiation loops. The 45° elbow fitting as an example saves 30% of piping and reduces head pressure significantly over a 90° elbow run. All this increased pipe volume and head pressure reduces the natural gravitational convection effect, not to mention lessening materials, labor and lifetime operating costs of the system.

    Our Delta-T Mode Circulator measures this head effect well via its wattage indicator. All of our single, dedicated system circulator Beta Site installs to date exhibit an 8 to 13 watt distribution power consumption upon a 20° delta-t (adjustable) differential attainment. Compare this to 80 watts typical for each 16gpm fixed-speed circulator or 20 to 25 watts each for the equivalent delta-t or delta-p install. With delta-t you can witness the wattage steadily decay to half or less as natural convection continues. We refer to this as “paddling your canoe with the current”.

    A secondary effect of gravity convection seems to be radiation heating profile modification, smoothing demand amplitude variation and increasing comfort. Some of the extended fuel savings we observe and the delta-t manufacturer claims seem to be due largely to this radiation profiling effect. Another contributor is the lowered system operating temperature effect of using a very high mass cast-iron boiler vs. contemporary low-mass units. Burner operation cycles are significantly less frequent and briefer than the system it replaced.

    A personal observation: this author has never replaced a “cold shot” cracked or magnetite impaired cast-iron boiler in over sixty years of hydronic and steam installations. Perhaps a discussion for another day, but have we also “thrown the baby (cast-iron boiler) out with the bath water” to cite this adage?

    Finally, the combination of high thermal system mass with enhanced gravity convection extends selective fail-mode heating continuity substantially. Recently and four years prior our Beta Site #3 experienced a fail-safe circulator interruption. The latter an over-current condition from a voltage surge “fail-safed” its operation. In both instances the condition was not discovered for an estimated 2 to 3 days, despite significant heating demand. Neither living area heating nor indirect DHW generation were affected. Second level heating reduction was eventually noted, as it was prior. The customer called and we reset the power switch over the phone to resolve. It is also noteworthy that we have had no system related service calls in over twenty aggregated operating years on our multiple Appliance Beta Sites!

    In closing, the contemporary excesses and misapplication of hydronic distribution are troubling to this author. If tradesmen are promoting their field distribution piping efforts as efficiency measures they are sorely misdirected and possibly even deceitful. Witnessing customers proudly showcasing excessively installed systems or trade supplier contests for the “prettiest system” installation pics are also particularly disconcerting.

    Perhaps it is time for an engineered “appliance” approach to rein in this “Plumber’s Playground”.


  • THE DELTA-T ECM CIRCULATOR — The “Automatic Transmission” for Boilers

    After speaking on-site  with a local customer about his system, he inquired as to what else we were doing. A mistake on his part.

    Both of us having differing technical backgrounds I launched into an inspired dissertation of our application of Delta-T ECM Circulation to Residential FHW Heating Systems. Obviously very interested, a running Q & A exchange of increasing technical depth ensued to the point of my noting he was developing that “deer in the headlights” look of incomplete understanding.

    We engineering types have a terrible habit of technically overloading our audiences, not as an “ego-trip”, but to inform as effectively as possible — we think!

    Needing to salvage the situation I paused, desperately searching for that inspired “bolt of lightening” to strike and clarify the atmosphere. By seeming grace, it came immediately! “I’m putting Automatic Transmissions on Boilers.” Yeah”, he responded, “that makes complete sense. Good idea!” Our further conversation became an analogy of FHW Heating Systems to Automobiles, surprisingly clearing our technical disparages. To expound …..

    After all, hot water boilers and automobile engines are both truly “heat engines”. An automobile engine must convert as much fuel combustion energy into mechanical propulsion power as possible via pistons, crankshafts, etc. Less than 60% becomes useful power, the remainder is dissipated as waste heat. The hot water boiler on the other hand necessarily converts its fuel combustion energy directly into useful heat at up to 97% efficiency!

    The automobile uses a transmission to adapt its mechanical power to control vehicle propulsion. A variety of gears, pumps, valves, etc. are used to accomplish this. The hot water boiler conversely needs only to move heated water (via a pump) exactingly to ideally acclimate our heated areas and (optionally) our domestic hot water (DHW).

    The Delta-T ECM (Differential Temperature) Variable Speed Circulator (Pump) is that ideal “boiler transmission” that delivers heated water most efficiently to maintain our comfort. So efficiently does it do so as to reduce system fuel consumption by up to 15% and electrical consumption by up to 85% as documented by Taco, Inc. Published Testing Results.

    No longer is heating system efficiency measured solely (and inaccurately) by the Boiler AFUE (Annual Fuel Utilization Efficiency) Rating, but the aggregate of Boiler, Distribution and Radiation Efficiencies. There are THREE (3) Elements in a hydronic heating system! Just as in Sulky Racing, it’s the combination of the horse, the jockey and the buggy that wins races.

    Even more exciting  is the opportunity provided by the Delta-T ECM Circulator to most efficiently configure a FHW Heating System, which we have done very effectively. Refer to our other, recently published Delta-T Blogs on this site that detail our development, field testing and observations of our systems.

    Our “Packaged Delta-T ECM Hydronic Heating Appliance™” (Patents Pending)exhibits the following attributes in direct comparison to the typical “conventionally installed” system:

    1. Has a higher Combined Boiler AFUE and Delta-T ECM Distribution (System) Efficiency than achievable with any “conventional” system configuration.
    2. Consumes less fuel and electrical power than any equivalently sized system.
    3. Our Integrated Boiler/Indirect Water Heater System occupies 1/3 to 1/2 the floor-space of others.
    4. Our proprietary Fully-Iron & Cast near-boiler piping maximizes durability and distribution performance using fewer materials.
    5. Further combining a High-Mass Boiler with an All-Stainless Indirect Water Heater assures a dramatically projected economic life (30 years or more?).
    6. A true universal, multi-fuel Appliance. Just change the burner —– not the system!
    7. Provides, Simple, Durable, Efficient and Cost-Effective FHW Heating.

    So yes, we do put “Automatic Transmissions” on Boilers!

    Author’s Note: Updated 07/23/2018


  • BEYOND AFUE’S – TOWARD REAL HYDRONIC (FHW) HEATING EFFICIENCY!

    For the past year Mercier Engineering has been immersed in developing and preparing for market it’s Packaged Delta-T Hydronic (FHW) Heating System™, based on our past heating experience projected into the new world of “Delta-T Circulation”. You may have noted our preoccupation with this technology in “The Heating Blog” on our www.boilersondemand.com  website. Time to “put our money where our mouth is”, so to speak. The results of our efforts we deem noteworthy and are initially reflected in this writing.

    As the titling of this blog purposely implies, we must get beyond weighing hydronic heating system efficiencies solely upon the boiler’s Annual Fuel Utilization Efficiency (AFUE) Rating.  It is only one of multiple elements in an operational formulation that is seldom if ever approached, even more poorly understood, and we allege almost universally misapplied. Strong words which must be tempered by the reality that there has been little market incentive to change our approach to serving the residential FHW heating market in particular; but we ultimately must adapt and change it for the consumer’s benefit.

    AFUE is a regulatory, laboratory testing procedure intended to establish an efficiency value for a hydronic (hot water generating) boiler under a defined operating sequence and conditions. It can be presumed that it executes this comparison very effectively, under its terms. However, what it does not measure from our observations is in practice very significant. Specifically these Non-AFUE Test Attributes are:

    1. There are no provisions for qualifying or measuring between-cycle “stand-by” or “idle-time” losses. This is the time between burner firing cycles when the boiler is prone to radiated energy and convective exhaust (flue) losses, presumed to be non-productive.
    2. Similarly, the testing is “steady-state” in execution, providing no qualification or quantification of individual boiler attributes that may contribute to site application efficiency.

    These test attribute observations have been borne out in field applications, where system performances have not correlated well, boiler-to-boiler or system-to-system. To further complicate this is the variability of physicals to each application, however subtle. The forums and blog sites are rife with these seemingly “apples-to-oranges” commentaries. Our developmental efforts may be able to provide some explanations.

    From our observations there are necessarily five (5) elements contributing to total system energy efficiency:

    1. The boiler (heat engine) energy conversion efficiency or AFUE.
    2. The physical attributes of the specific boiler complimentary to system operation.
    3. The energy required to move heated water through the distribution system (radiation).
    4. The effective matching of radiation elements to heating demand.
    5. The control algorithm(s) to match energy creation with varying system demands.

    Our initial efforts have been with oil-fired hydronic systems and is the focus of this document, with gas-fired and solid-fuel applications to follow as resources permit. However, much of this effort is applicable as the basis of other heating systems.

    Varying the output (energy creation rate) of any heating resource is paramount. This has been readily achieved in gas-fired boilers by “modulating” combustion with sophisticated valving and controls. Typically they adjust from 20 to 100% of capacity, from “idle” to “full speed” to use the automotive analogy. However, direct modulation of oil-fired systems is not feasible using current technologies. A fixed (capacity) firing rate via pressurized, nozzle induced fuel atomization is the norm. Therefore, the only option is to adjust the operating temperature of an oil-fired hydronic boiler via controls to compliment heating demand. This is reasonably well-managed with modern “cold-start” aquastats, external temperature sensors, etc.

    The prior unaddressed penalty to particularly residential hydronic systems has been the toll on equipment and electrical energy requirements of circulating heating water with fixed-speed circulators. They are notoriously and arguably universally misapplied and inefficient in practice. Reducing water temperatures merely aggravates the situation by prolonging circulator cycling.

    Fortunately technology has come to the rescue in the form of the “Delta-T” Circulator, now becoming very applicable and affordable to the residential/light commercial markets. The undisputed pioneer and flag-bearer in this market is the Taco Viridian VT2218 found at this link: http://flopro.taco-hvac.com/media/Viridian_VT2218_100-114.pdf  To use the quote “This changes everything” is not an exaggeration! The Viridian is in fact the second generation, replacing the entry product Taco “BumbleBee” found at this link: http://www.taco-hvac.com/uploads/FileLibrary/100-101.pdf We mention the “BumbleBee” only because it has rapidly become a “cult product” in the HVAC Community, somewhat akin to the “Trekkies”. It was our initial “new tool” in developing and thence refining our product(s). Like our brothers, we hate to see it go as we move to the refined and more sophisticated “Viridian”.

    Referring back to our five (5) elements to total system efficiency, Delta-T Circulation is number three (3) on the list but is deservedly and necessarily the foundation of any hydronic system improvement. Taco reports system Delta-T Circulator-only swaps yielding 15% fuel usage reductions. It is the keystone of our Packaged Delta-T Hydronic (FHW) Heating System™, and should be the first improvement to any system! We caution however that this will require substantial near-boiler system re-piping and your installer must be knowledgeable. It is discouraging to note how few of our fellow tradesmen are cognizant of Delta-T or have used it beyond a radiant heat loop. We “Old Dogs must learn new tricks”, and we have!

    The second element of import is the necessity to employ “Cold-Start” Boiler/Aquastat Hydronic Technology, which overlaps Nos. 2 and 5 in our list. We are unabashed in our praise of the Hydrolevel 3250-Plus “Fuel Smart” Aquastat, found at this link: http://www.hydrolevel.com/new/images/literature/sales_sheets/fuel_smart_hydrostat_sales_sheet.pdf   It is now standard equipment on all our Weil-McLain Ultra Oil Boilers, and none too soon! The inter-action of the 3250-Plus with the VT2218 Circulator’s operational software is paramount to total system performance, as we have learned.

    Note: “Cold-Start” Technology applies to “heat-only” boilers. DHW (Domestic Hot Water) must be effected by an external Indirect Water Heater or another dedicated appliance. We combine the Indirect Water Heater in our design for optimized Heat and DHW Generation.

    Element 3: Our development indicates individual boiler attributes are significant. Specifically,

    1. Boiler supply and return tap placements are crucial to system “packaging”, i.e. the ability to compactly (efficiently) structure near-boiler piping. (We can pipe into a space as close as 11″ from the chimney, with all piping and controls behind the boiler, yet readily accessible.)
    2. A very high boiler mass (weight) for its capacity, i.e. for both thermal damping and storage.
    3. Favorable exchanger flue passage routing and exhausting.
    4. Burner type to compliment its attributes.

    The noted attributes lead us to our “Boiler-of-Choice”, the Weil-McLain Ultra Oil Series with the Beckett NX Burner. Refer to this link for detail: http://www.weil-mclain.com/en/assets/pdf/Ultra%20Oil%20Brochure_8%20Pg_web1.pdf   We have had “conventional” system design and installation experience with this boiler for over ten years now, with only one “no heat” service call, a failed aquastat. Weil-McLain has since upgraded it to the Hydrolevel 3250-Plus, thank God!

    The Beckett NX Burner has been likewise flawless in operation. Literally a “plug and play”. Its dual vent typing capability (direct & chimney) has proven beneficial to problematic venting applications, especially when encountering “cold chimneys” in our northern climate. Fully exposed exterior chimneys are sure to give a rough startup without utilizing its pre-purging and pressure firing features.

    The key attribute to system performance outside of Delta-T Distribution has proven to be Thermal Mass (Storage) provided by the sheer robustness (weight) of the Weil-McLain UO Series High-Mass, Triple-Pass Boilers. They are “The Heavyweight Champions” by far and as a result exhibit lower mean boiler operating temperatures and very less frequent burner cycling.

    As a matter of policy we do not cite or criticize our competitors, but we must make a single attribute comparison to emphasize our point. The approximate block weights of the top hydronic (approx. 100KBTUH, 87% AFUE) oil boilers are:

    Manufacturer/ModelApprox. Ship Wt.
    less Tare (lbs.)
    % of HighestComments
    Buderus G115/G21537560%Adjusted for 100KBTUH
    Burnham MPO-IQ11545072%
    Weil-McLain UO-3625100%

    Author Note: Very noteworthy, the Weil-McLain is also disproportionately the lowest cost per pound (by nearly half) of the three. Just what is the consumer paying for, we wonder?

    Radiation (Element 4) efficiency is the remaining, but least controllable variable in a heating system. It is substantially outside the scope of our system application, yet there are some performance elements we can address.

    Existing hydronic radiation:

    1. Removal of unnecessary valving in zone supplies and returns. All zone control functions are integrated into our system package.
    2. Zone interconnections can be optimized by correct pipe sizing and routing. It confounds us as to why some plumbers use virtually no 45° fittings! You can use 3-4 of them vs. a 90° elbow for the same flow resistance, and you use only 70% of the pipe required for a 90° elbow routing.

    New hydronic radiation:

    The contemporary approach to radiation varies widely, from simple radiation loop(s) for zoned heated areas to individually heated rooms throughout. The more finite the control, the more piping, fittings and control valving, and the more hydronic distribution energy is required.

    Ironically, the same Delta-T Circulator Technology we employ to maximize our system performance has preceded us and become the darling in particularly radiant system applications. We have also employed them in these and they perform admirably. They reduce the energy requirements significantly but yet still camouflage the basic issue.

    If your concern is total energy consumption of a system, we would invite you to consider using less sophisticated radiation distribution schemes. A properly designed, installed and balanced series or split piping loop exudes simplicity and will likely be a lower installed cost. The KISS Principle applies — keep it simple ….. (Refer to our Heating Blog Library for additional detail.)

    To Summarize:

    1. Additional Boiler Attributes are important, beyond the AFUE Rating. In particular heat exchanger thermal mass (weight) will lengthen service life while minimizing repair costs. Burner attributes related to exhausting and tuning must also be considered.
    2. Delta-T Hydronic Distribution Technology is the key to improving any system’s energy performance, both for heating fuel and electrical power consumption.
    3. Inter-related “intelligent” controls determine system operational performance. They are currently the Hydrolevel 3250-Plus Boiler Aquastat and the Taco VT2218 Delta-T Circulator Logic.
    4. Near-boiler plumbing in particular affects system performance. This is maximized in our system piping configuration to include fail-safe “gravity convection”.
    5. Interconnection between our system zone access points and the existing must be executed with the goal of minimizing flow anomalies.
    6. Existing and/or new radiation installations must likewise be executed by idealizing flow conditions inasmuch as possible.

    References:
    We strongly recommend referring to Taco’s website: http://flopro.taco-hvac.com/deltat_resources.html and refer to the various Delta-T resources therein. There’s a volume of resources here that will properly inform you of this new technology and its place in your Hydronic (FHW) Heating System.

    Author’s Note: Hyperlinks updated 08/22/2017


  • HIGH EFFICIENCY CONDENSING FHW BOILERS – The Dirty Little Secrets

    The popularity and performance of condensing gas technology hydronic (FHW) boilers is both noteworthy and deserved. Kicking up heating gas fuel (Natural & LP) efficiencies from the prior generation average of 80-85% to 90-97% in one technological step is astounding. However like any new technology it has come at a price, both positively and negatively. Problem is the negatives are not discussed with the sales enthusiasm.

    It doesn’t take a very sharp pencil to justify a condensing boiler upgrade from a prior generation unit, and particularly a much older one. That 10% or (much) more is significant itself, but coupled with an indirect water heater operating as a “cold start” system can yield 40% or more in our experience. So where are the issues?

    Hydronic boilers have traditionally been constructed of cast iron or of welded steel plate as a lower cost alternative. The welded-plate alternative has failed historically in both durability and efficiency. We have noted recently a disproportionate number of steel boilers appearing locally in “upscale” newer homes. After all, contractors have to cut costs somewhere!

    In the gas market we are moving to new materials to compliment both the cleaner and more controllable combustion afforded by Natural Gas and LP (Propane). These boilers can “modulate” (adjust) their firing rate up to 80% to accommodate heating demand, much like pressing on the gas pedal of your automobile from an idle to adjust power and speed. This is accomplished using a sophisticated sensor and control system. So now we can utilize materials that are more favorable, specifically aluminum and stainless steel, but for very differing attributes.

    Referring to aThermal Conductivity Chart you can appreciate why copper is so commonly used as a heat-exchanger material in baseboard with thin aluminum fins to compliment. Cast iron is so-so but stainless steel is very poor. So why use these particular materials?

    Cast iron is typically used in larger, heavy sections with a generous amount of water as a “thermal mass” device to manage both combustion and energy distribution. (Refer to our Blog:HIGH-MASS VS. LOW-MASS BOILERS – THE ARGUMENTSfor more detail.)

    Aluminum would also seem to be very desirable in this regard excepting that it is very susceptible to chemical corrosion and must be alloyed and/or chemically surface treated for protection.

    Stainless steel on the other hand is a very poor heat conductor, but with very good corrosion resistance. Designers must therefore carefully define the stainless steel heat-exchanger to attain performance while utilizing a substantially more expensive material. With much poorer thermal conductivity, material thickness and heat transfer surface area become prime design parameters. However, coupling this with the necessity of welding stainless steel components together for structural and process integrity and you have a metallurgical compromise.

    Corrosion is the common denominator in all heat-exchanger materials, caused by oxygen and minerals naturally present in water. As such, appliance manufacturers must deal with their eventual effect in their design executions. It’s not IF, but WHEN chemistry wins. Thus the only way to predictably present a hydronic (or steam) boiler to market is to specify the water quality requirements of the system. Note: All condensing (and other) heating appliance manufacturers detail pH (acidity) and additional water conditions in their product documentation and in their Warranties!

    For the past decade or so, manufacturers have been quietly honoring warranty claims against condensing boilers that are clearly the result of poor water conditions. Cast iron boiler durability on the other hand has always been manageable. We presume that honoring condensing boiler warranties was a calculated marketing effort to promote the new technologies and systems, but no more.

    Weil-McLain (our flagship supplier) is renowned within the heating industry for its warranties (and leniency). We have dozens of stories to reinforce this supposition in fact. “The customer is (virtually) always right.” However, speaking recently with Weil-McLain Field Personnel has prompted this blog both reflecting the industry’s necessary strategy change and the ultimate effects upon the consumer.

    The extent of water quality management and documentation may vary within particular suppliers, but be assured that it is happening! This will be very evident not only in new system documentation but inWarranty Claims on existing condensing boiler systems, the most susceptible and therefore the industry focus.

    Therefore you, the consumer must now “have his ducks in a row” by:

    1. Verifying that the water condition requirements of your boiler are met upon installation and start-up by yourself or your installer.
    2. Documenting your water conditions then and thenceforth.
    3. Qualifying that your serviceman performs the specified pH (Acidity) Test during maintenance cycles.
    4. Keeping these maintenance records on file.

    Note: A similar situation exists in degree within the On-Demand DHW (Potable Drinking) Water Heater market. We in fact are certified and install the premium brand unit. They strongly recommend annual flushing with white vinegar to maintain heat-exchanger integrity. (This requires suitable piping installed on the unit, pump, etc.) Immersion coil heaters within boilers have historically had this issue, but not to the degree of the on-demand units due to their design attributes (less restrictive fluid passages). Their replacement cost is also more reasonable in comparison to an on-demand unit.

    So, hard water can become hard times! Be prepared.

    Continuing with our representatives’ conversations, they further offered an enlightenment that won’t be found in print. Specifically, that the life expectancy of a condensing gas boiler is measurably more limited by water conditions and average life is projected to be substantially less than its less sophisticated predecessors. Their average heat-exchanger replacement life expectancy from a marketing perspective on a condensing boiler, considering the heat-exchanger construction material is:

    1. Aluminum — approximately six years.
    2. Stainless Steel — approximately ten years.
    3. Cast Iron — over twenty years.

    We are in no position to qualify or disqualify these statements, excepting to state that we have had an aluminum heat-exchanger failure at six years. It was replaced at no charge (of course) by Weil-McLain. The water condition at this installation was poor, but had been treated by a salt-based softener. How effectively is the obvious question?

    Note: A heat-exchanger replacement cost can approach half that of the initial boiler.

    No field histories on stainless steel heat-exchangers have been published, so again we must defer to judgment.

    In either case, the substantial differences in both initial condensing gas appliance costs and life expectancy must be considered in making a purchase decision.

    Cast Iron is a different matter altogether. It has been the material-of-choice for hydronic and steam boilers from the onset of the Industrial Age. They live long and harsh lives, particularly as “steamers” where their iron is literally eaten by continual ingestion of fresh water (oxygen and minerals) to create and vent steam as the heating medium. A precipitated “black goop” settles in their bottoms and must be periodically flushed to avoid corrosion and a circulation stoppage. (Note: Steamers typically have heavier castings to suit.)

    There is also a unique hybrid stainless steel/cast iron condensing gas boiler available from Weil-McLain (of course). TheirModel GV90+ Gas Boilerhas a primary cast iron heat-exchanger coupled to an external stainless steel “condensing” exchanger. The combination provides an extremely longer-lived condensing boiler, readily serviceable with modular replacement at a respectable 91-92% AFUE Efficiency. So now there is an alternative with a seemingly longer economic life, but at the penalty of a few points in efficiency less than its more sophisticated cousins. Do the numbers justify the hybrid’s 3-5% lower efficiency and its 20% lower initial cost for a potentially doubled system lifetime?

    Before you “run the numbers”, consider this point. Presuming that the hybrid has a double life over the aluminum or stainless units, you will effectively buy a second unit with no economic incentive at all. At 97% AFUE we have, to quote the old farmer’s saying: “Used everything from the pig except its squeal.” There are only 3 points of efficiency left to play with, most of which is likely technically non-achievable.

    Note: We have not discussed heating oil and other fuel conversions to/from Natural Gas. LP (Propane) in our region remains, and likely always will be a more expensive “fuel of choice”. Refer to our Blog:OIL TO GAS FHW HEATING CONVERSION – ALL OF YOUR OPTIONS for applicable detail. Be mindful also that the past year has become an economic crossover for Heating Oil vs. Natural Gas, particularly when the Crude Oil Per Barrel Cost stays under about $45. We have a recent Blog:OIL & NATURAL GAS AS HEATING FUELS EQUATE @ $45/bblthat can serve to further inform ….. and confuse! Further, Natural Gas is not tracking #2 Heating Oil well, the differential widening substantially. So $45 is probably a low number today …..

    So what conclusions can we offer?

    1. An older Gas Boiler upgrade to a Condensing Gas Boiler is a “no-brainer” economically.
    2. Heat Exchanger Material choice, considering your water condition, is paramount.
    3. There are not two but three condensing gas boiler options available: Aluminum, Stainless Steel and a Cast Iron/Stainless Steel Hybrid.
    4. Condensing Boiler Life is a real factor. Check the Warranties and Conditions!
    5. Factor both efficiency increases and potential system life decreases into your calculations. Initial system cost is also a variable.
    6. Your water condition documentation is paramount.

    Summarizing, the Condensing Gas Boiler is the contemporary appliance-of-choice for cost effective residential heating, where applicable. Hopefully providing you with all of the rules of the game will make you, the consumer, a better player.

    Author’s Note: Recent HVAC Trade Journal Articles are beginning to document premature material and weld failures (leakage) in condensing boilers, some immediately upon or within weeks after installation. Some can be attributed to factory process control by manufacturer, but underlying is that basic metallurgical integrity factor. There is no field repair option yet available.

    Updated 06/29/2017 P.D.M., Sr.


  • THE CASE FOR SEPARATING HEATING INSTALLATION FROM SERVICE

    Our singular observation in over 50 years of hydronic (FHW) heating systems installation and service is this: Given any similar application, no two heating systems are configured the same, nor do they consequently service the same. Need they be? We argue that they definitely should be alike for both operational and service efficiencies.

    The impairment to maximizing hydronic efficiency and service lies within the heating market itself. Manufacturers supply components and installers apply them to the customer application employing their accrued experience. The obvious result is the installation variations we observe – “the good, the bad and the ugly” to apply the popular quotation.

    The problem is that even the good is not good enough efficiency-wise, and the installers get little help from their component suppliers, representatives and technical services in this regard. Specific to hydronic boilers, the “building block” of all FHW Systems, the manufacturer provides a generic installation guide with plumbing diagrams and wiring schematics that cover all the bases. No effort is given to efficient component sizing, placement or utilization. Much like an artist that is given a clean canvas with an image theme, the installer creates his own picture as he sees it.

    Ironically, there is an innate need for plumbing and heating guys to paint their own canvas. The daily tedium of fixing “leaks and squeaks” gets old very quickly. The opportunity to become creative by building a heating system on-site and making it look seemingly neat and pretty is a strong draw, not to mention a great payday as well. LEGO’s for Big Kids! Problem is, the customer pays for it up front, and continues to pay over the lifetime of the system in fuel, maintenance and operational costs, knowingly or not.

    From an engineer’s perspective the solution is quite simple, a designed and configured PRODUCT built specifically for the application. The quandary however is: How can you possibly accommodate so many applications and individual variations? There is seemingly an endless possibility of pipes, circulators, controls and valves to idealize an application. This has been the traditional dilemma — until recently. Technology to the rescue!

    Hydronic systems are undergoing a true design revolution with the development of “smart” circulators and zone valves. The combining of these reduces virtually any common residential or light commercial hydronic application to a single circulator and compliment of zone valves to suit. The resultant is a very efficient, flexible and yet simple system. We strongly recommend viewing our companion blog THE HYDRONIC REVOLUTION – THE INTELLIGENT DELTA-T CIRCULATOR FHW SYSTEM for further descriptive and technical details.

    Now to define a typical residential or light commercial system you only need to:

    1. Calculate the total heat loss of the structure.
    2. Specify a hydronic boiler and fuel type with suitable capacity.
    3. Select either a natural draft or forced exhaust venting.
    4. Qualify the use of an indirect water heater, if applicable.
    5. Determine the number of heating zones and their respective supply and return points.

    Note: These comments apply only to a Hydronic Boiler Packaged Product. Heating distribution compliments and completes the system, either as a new or in a replacement application.

    There are currently, to the best of our knowledge, no pre-built, assembled FHW Boiler Package Products applying the latest technologies, assembly methods, materials and logistics to support this emerging market. We are defining the attributes of this market to be providing:

    1. Hydronically optimized boiler package providing exceptional performance.
    2. Intelligent, ideal energy delivery and control.
    3. Complimentary supply zone distribution.
    4. Complimentary zone returns with service enhancements.
    5. Quick, simple on-site preparation and fitting.
    6. Ideally, availability on-demand.
    7. Expedient delivery to site, as required.

    Given the attributes and performance of this product, it will lend itself to service ease by any reasonably skilled personnel. The challenge remains to break the customer from the current norm of “one-stop shopping” for heating installation and service, the intent of this writing. It is only by providing and displaying the performance of such a product will we break the status quo — for the benefit of the consumer, and as an asset to the installer as well!

    We (Mercier Engineering) have participated concurrently in both high-technology manufacturing and the heating trades for over fifty years. An opportunity is now provided to us to participate in developing and marketing this Hydronic Boiler Product. Our career skill-set strongly compliments this task and thus we will be introducing a series of products to develop this emerging market.

    Please follow us on our website: www.BoilersOnDemand.com

    Our “Mission Statement” therein defines us and our goals..


  • WHAT SIZE BOILER DO I NEED? – MEASURE YOUR RADIATION

    If you have read our other blogs you will note that we are advocates of using a Heat Loss Calculator to determine your heating system boiler size and radiation requirements. However, when replacing an existing boiler in a hydronic (forced hot water) system a shortcut method is available, subject to some qualifications.

    Measuring your total radiation (baseboard registers, radiators, cabinet convectors, unit heaters, radiant, etc.) can provide a good estimate of boiler size requirement. Simply put, installing a boiler that is larger than your radiation capacity is foolhardy. Excessive energy delivery cannot be utilized.

    Common residential baseboard is typically rated at between 550 to 700 BTU’s per linear foot, and typically at a water delivery temperature of 180°F by the manufacturer(s). These values vary with the construction, by manufacturer and somewhat by register height. A “rough measure”:

    1. 7-1/2” or under height = 600+/- BTU/Ft. (Variation +/- 50BTU)
    2. Taller than 7-1/2” is likely 700+/- BTU/Ft.(Variation +50BTU)
    3. Cast Iron Residential Baseboard is usually around 600BTU/Ft.

    Notes:
    1. There is no substitute for identifying your specific manufacturer’s product and specification, if possible.
    2. The “dirty little secret” however is that most of the baseboard radiation produced (particularly in New England) is by one regional supplier, and branded for boiler manufacturers to their specification. Thus the subtle aesthetic variations in sheet metal profiles.

    Given the prior, merely measuring the nominal length of your “fin tube”, adding them up to obtain a total radiation length and multiplying by your estimated BTU/Ft. selection gives you a total radiation BTU capacity, and hence your boiler output requirement.

    This covers the prevalent usage of baseboard radiation as a FHW heat transfer medium, but what about the others? They must be addressed separately as follows:

    1. Cabinet Convectors: These are usually readily identifiable and many have their output specifications on a product label (external or internal).
    2. Unit Heaters: Typically found in basements, garage or work areas for incremental use. They have an external chassis specification label with rated values.
    3. Radiators (typically converted from prior steam usage, but not always): The number of original suppliers and variations of these is daunting. There are online resources citing dated cataloging that is useful, but you have to dig!
    4. Radiant Radiation (In or under-floor tubing) calculation is more challenging. You must know the actual length and size of tubing utilized by whatever means or design records available.

    There are other considerations to both qualify and quantify once you have your total BTU requirement calculation.

    1. When replacing a dated boiler (in a dated system) you must qualify what has been done to the heated structure in the interim. Particularly any energy requirement changes effected by millwork (door & window) and insulation improvements must be considered.
    2. Have energy improvements changed the heating “proportions” of radiation requirements, exhibited by uneven room heating? If so, add radiation to extremely affected areas where overall balance cannot be achieved by adjusting dampers on all radiation.
    3. There is a benefit to be gained by having excessive radiation effected by energy improvements. Specifically, temperature change requirements can be readily achieved, permitting thermostatically controlled, energy-saving setbacks.
    4. Similarly, the equipment duty cycle and mean boiler temperature reductions add up to measurable operating cost reductions.

    Regarding Items 3 & 4, we offer two “new system” observations:

    1. Some new homes are designed so radiation-marginal that functional thermostat setbacks are minimal, if at all achievable under deep cold conditions.
    2. Full house “under-floor” and “in-concrete” tubing radiation systems offer virtually no significant temperature set-back capabilities, a notable energy penalty!

    Summarizing, weigh the operating characteristics of your particular hydronic system application before selecting any boiler. Over-sizing beyond your radiation capacity is a waste of money. Given that:

    1. There is still no substitute for a well executed Heat Loss Calculation
    2. Look at an intelligent FHW distribution option such as the “Delta-T” System. A great system improvement that returns great benefits! (Read our other Blogs.)

    As another resource, Weil-McLain has a new “Boiler Replacement Guide” (Linked) that we highly recommend.

    “Times are a-changing” as they say, and quickly. Don’t miss the bus!


  • MAXIMIZE HEATING EFFICIENCY WITH A SINGLE ENERGY SOURCE

    Optimization of heating efficiency first requires determining your specific requirements. In general terms there are two or more distinct heating energy uses:

    1. Area Heating – Warming occupied areas fully, or selectively as living habits occupation or use may demand.
    2. Domestic Hot Water  (DHW)– Heated, potable (drinkable) for baths, showers, laundry and personal consumption.
    3. Special Uses – High temperature power washing, sanitizing, etc. (Refer to prior blog.)

    All of these requirements can ideally be met by using a hot water boiler system as a single, central source but the question arises of how to accomplish this efficiently. Specifically, varied heating demands that may range from continuous (?) DHW to very occasional (seasonal?) and selectable area warmth can become a challenge, particularly economically. However occasional demands can “lighten your wallet” to execute and maintain. Let’s address this problem systematically.

    Arguably the most important decision has to be your heating fuel selection. We cannot overemphasize this and the use of a Heating Cost Comparator to define your choice. (See our other blogs.) The standard unit of measure is the “Cost per Million BTU” expressed as a dollar figure. We use the NH-OEP Calculator for our area usage, but similar ones are available online. Use your current or projected new heating appliance efficiencies (AFUE) to get an accurate calculation. New Gas (Natural or LP) AFUE’s are typically 95% for top end (condensing) boilers and 87% for Oil Triple-pass boilers.

    The current and foreseeable heating fuel choices have become quite obvious in the northern climates:

    1. Natural Gas (where available) is the accepted baseline. But BE CAREFUL! Natural Gas is a “distributed fuel” (through a pipeline). Your actual bill will be considerably higher due to service and distribution costs added to your actual therm usage. Get a billing estimate from your gas provider first! (Our local multiplier is up to 2.0 or 100% added for your actual natural gas billing costs.)
    2. Heating Oil is the predominant fuel where natural gas is not available.
    3. Liquid Propane (LP) Gas is another option along with oil where natural gas is not available. LP has been used predominantly for domestic cooking and somewhat for DHW generation. As an area heating and DHW fuel it has traditionally been up to a 100% premium over oil. It is a heating option of choice in our experience.

    Note that solid fuels (wool, coal, peat, waste, etc.) have been purposefully omitted from this discussion. Insurers typically disallow continuous firing fuels using interior combustion equipment. External or “outdoor boilers” are “zero pressure” and require a “plate exchanger” interface with an internal power fired system to assure continuous heating maintenance. Verify these statements and weigh potential penalties for your particular situation.

    Consumers predominantly identify their area heating options as Forced Hot Air (FHA) Furnace or Forced Hot Water (FHW) Boiler Systems. Similarly DHW options as Electric, Gas or Oil stand-alone Water Heaters or from an immersion coil within a boiler. So therefore we usually find the typical FHA System with a stand-alone DHW Heater as a combination. FHW Systems usually provide DHW from an internal Immersion Coil, as previously noted. Currently we are seeing the emergence of the Indirect Hot Water Heater, supplied by a boiler as the efficiency choice.

    But in fact our heating options are more extensive. They include:

    1. Air Handler– A FHA Furnace without a fuel-powered heating source. Instead it has an internal large radiator (heat exchanger) that is externally supplied with energy from a FHW source (boiler).
    2. Unit Heater– A radiator with fan, typically found as an overhead heater in a garage, warehouse, etc. There are also variations of these with provisions for attaching ducting – otherwise similar to an Air Handler.
    3. Plate Heat Exchanger– Basically two (or more) mutually integrated radiators allowing the interchange of heat from varied sources. Source variation attributes may be pressure, temperature, flow rate(s) and composition. Their composition may be aqueous (or not) and adjusted for properties such as freezing and/or boiling resistance.

    Utilizing these latter devices allows us to employ higher efficiency or lower cost hot water generation sources (or both) for all our area and DHW heating requirements. We respectfully suggest that where a single, efficient energy source is desirable or necessary for continuous demand a FHW boiler should be employed. Further, that this source then be applied to all your structure’s heating demands with all the resources detailed within.

    The unmentioned physical fact is that utilizing water as an energy conductor is inherently and significantly more efficient than air. Thus an HVAC System (air heating/cooling) is less efficient than a hot water boiler (heating) coupled with an air handler (cooling) combination. This can be witnessed in their assigned AFUE values.

    So, let us wrap it up by considering some common scenarios for our FHW boiler system source:

    1. A Central HVAC (Heating,Ventilation & Air Conditioning) System Upgrade.

      • Upgrade the existing FHA Furnace with an Air Handler, if desirable, or
      • Install a FHW Heat Exchanger (radiator) into an existing FHA Plenum, plumb and rewire as necessary.
      • Install a “Chiller” in the Hydronic System to provide an A/C source.
    2. Existing or planned FHA System Upgrade – Same as 1. without A/C.
    3. FHA installation into a seasonal, incremental, unheated area or as an expansion.
      • Install an Air Handler or Unit Heater variation to suit.
      • Where freezing protection is desirable, employ a Plate Heat Exchanger with anti-freeze as necessary.
    4. Use a Plate Heat Exchanger to couple “incompatible” secondary heated water sources such as exterior wood & coal boilers, solar & geothermal loops, etc.
    5. In all cases, move to an Indirect Water Heater for efficient DHW generation.

    By the way, these new high efficiency boilers do not necessarily need a chimney. Condensing Gas Boilers typically use PVC pipe for venting and Triple-Pass Oil Boilers with Pressure-fired Burners can use a direct exhausting vent kit.

    Have we run you out of options yet?

    Last Edit: 10/18/2018 pdm


  • CONVERTING A STEAM HEATING SYSTEM TO HOT WATER – THE WHYS AND HOWS

    Steam Heating Systems were the Cadillac of heating options for residential applications for about a century. Pricey, tending to be a bit fuel-thirsty (regardless of the fuel used), they were extremely simple, durable and provided a superbly comfortable heated environment. Economics have gradually forced steam heating into the commercial and industrial process realms alone. So where do you go with that residential steam system? It depends upon your goals.

    When do you stay with steam rather than change over to hot water or some other heating form?

    1. If you have a nice, period home that suits your needs excepting to lighten up on your wallet a bit, just upgrade the boiler to a modern, high efficiency unit. Older boilers typically are large, with open heating passages to suit both wood or coal fires that when upgraded to gas or oil result in very poor fuel efficiencies. Presuming the system piping and radiators are serviceable there is little incentive to change over the entire system. (Steam heating distribution is arguably more efficient than hot water!)
    2. Similarly, if you like those decorative radiators that warm your hands, food, dry clothes on, etc. and take up less footprint and wall space than hot water baseboard, think again.
    3. If you plan an addition or heated area extension and envision running steam piping everywhere to heat it, there is the little known and utilized steam boiler “bottom water” forced hot water heating option. Circulating the lower water below the steaming chamber (top of the boiler) provides extended heating system flexibility. Furthermore, forced hot water extends capability to attics, garages and additions with baseboard, Unit Heaters (fan forced radiators) and Air Handlers (a ducted FHA Furnace with an internal radiator that heats your hot air vs. using a gas or oil fuel source). You must however convert zero-pressure steam water into approx. 15PSI heating water for circulation to new radiation. A correct plate-to-plate heat exchanger is required and circulation both from the boiler and to radiation added. A separate water supply source and an expansion capability must be provided for the pressurized heating water circuit as well. Note: Remember to size your now “two-state energy” Steam/Hot Water Boiler accordingly.

    There is an interesting “middle ground” where you can convert your existing, newer steam boiler to hot water operation while keeping those aesthetic steam radiators. You must however replace all the old steam system piping in doing so. Steam radiators work well with hot water, but at moderately reduced heating (temperature) capacity. More importantly is the higher water volume content of steam radiators and how to supply them properly for even distribution.

    Referring to our separate blog on FHW Heating Loops, you can’t pipe cast iron steam radiators in series and get even heating! Even a split loop will not work but for a couple of radiators at best.  The only effective option is the mono-flow loop system, branched for each radiator. All will require increased piping and circulator capacity.

    Despite the challenges, converting steam radiation provides some attractive opportunities, heating-wise.

    1. You maintain your prior heated area aesthetics and functionality with few perceptible changes.
    2. You can now re-pipe and “zone” the prior area with multiple thermostats, even down to individual room level if you desire.
    3. Obviously you can add additional heated areas (zones) as well.

    Fully converting a steam boiler to hot water operation and then replacing or adding all heating distribution components is the last and most complete option. Scenarios:

    1. You have an excellent steam boiler with an economic incentive in mind. If you just wish to swap this unit out for your existing, inefficient or failed FHW Boiler as a one-for-one, be careful. Make certain that the conversion components and labor (as applicable) justify the changeover.
    2. Changing your existing, older steam boiler to FHW in our view is questionable. You are trading off operational efficiency against upgrade costs.
    3. Steam Boilers typically and Weil-McLain Steamers (our expertise) in particular have several advantages over their sister Hot Water Boilers. The front and rear sections are notably heavier and bulkier, containing more cast iron and water that can contribute to durability and theoretically capacity. Can’t speak for other manufacturers, but the Weils are heavier and tougher. Check their Specifications. Also if you are using a DHW Coil (immersion coil in the boiler to generate your domestic hot water), steam boiler coil(s) have nominally higher capacities and larger (Weil-McLain) boilers sometimes have two coils, or provisions for them for greater DHW capacity delivery. Check.

    A recent phenomenon is the Outside Wood Boiler. You know, that thing that sits beside a house that looks like a Metal Garden Shed with a Smoke Pipe sticking up out of it and a woodpile alongside. They are typically owned by rural folks that have a great wood supply and don’t mind tripping through the snow to keep themselves warm. These boilers are also “zero pressure” systems. They must be adapted to a pressurized FHW System through a Plate-to-Plate Heat Exchanger, utilizing circulators and controls. (You must maintain constant electric service to these systems or it can get exciting and cold, or both.)

    Coupling an Outside Wood Boiler to a Steam System is dubious at best. The only deliverables in this scenario are preheated boiler water that must be then fired and converted into steam by the central boiler, but which can also provide DHW through its internal coil (if equipped) or by an Indirect Water Heater (Insulated DHW Storage Tank) as an option. It just doesn’t make sense except to generate a lot of Domestic Hot Water. Therefore, in order to utilize the Outside Wood Boiler effectively you must do a complete steam boiler conversion (or a hot water boiler substitution) with the appropriate scenarios as previously detailed. There is no “easy road to glory” on this one.

    So procedural, to convert a steam boiler to forced hot water operation you must:

    1. De-plumb all iron and other piping right to the boiler. It must be “bare” as we say.
    2. Remove all of the electric components and associated wiring.
    3. Remove the Boiler Jacket (usually sheet metal) and place aside for reassembly.
    4. First, locate and substitute a 30 PSI (FHW) Pressure Relief Valve for the 15PSI (Steam) Valve. VERY IMPORTANT! Forget, and you’ll get wet — and surprised!
    5. Remove the Water Sight Glass, LWCO (Low Water Cut Off), Pressure Switch, etc. (Clean off the front of the boiler, in other words.) Dope and plug all affected boiler taps.
    6. Check Immersion Coil (DHW) Gasket(s) and Blanker Plates for leaks. Fix them.
    7. The smart guy plugs, fills the boiler and pressurizes it to 30 PSI (until the Relief Valve opens) and then checks for ANY LEAKS! Remember, steam boilers operate at about 0.5 to 5 PSI in use. You may have sectional leaking issues and not see them at that pressure. Sectional leaks between boiler castings are usually catastrophic. Stop and rethink your options. But, assuming it passes …..
    8. Find the manufacturer’s boiler piping diagram and locate the preferred aquastat front tapping and insert the appropriate “Spud Well” to receive the aquastat.
    9. Reassemble the boiler jacket and provide the opening for the Aquastat “Spud Well”.
    10. From the Manufacturer’s Hot Water Boiler Manual, identify the control components and hardware necessary to refit. Present this info to your Qualified Heating Engineer or Technician.

    Pay particular attention that your Master Aquastat selection compliments your application. There are several operational options available and should be qualified prior to final selection. Our preferred is the Hydrolevel “Fuel Smart” 3250-Plus Aquastatwith “Electro-Well” for all conversions.

    You now have a tight boiler ready to reconfigure for your application. Your further risk is minimal, save a hot operation leak(s) that may or may not be seal-able. Now consult and utilize a knowledgeable source.

    Be mindful that in converting any steam system to forced hot water you reduce the capacity of that system by 10% or more, if that is a consideration. Steam operates at a significantly higher system temperature in its vapor state than can be safely achieved with heating water safely below its boiling point.

    It may be implied from the above that we discourage steam to hot water boiler conversions. We have done it very successfully, once with an almost new Weil-McLain Gold Steamer and we’ve never been back. Do your homework!

    The option of acquiring a near-new FHW boiler instead of converting your steamer, particularly with the preponderance of on-going fuel conversions can also make very good sense.

    Hope this has helped you assess your particular situation.

    Updated: 11/28/2018 pdm


  • THE “POWER VENTER” – “Throwing Good Money After Bad”

    “Throwing Good Money After Bad” is a popular expression that is deservedly applicable to the “Power Venter”, a heating accessory device that enhances a poor chimney’s performance or substitutes for a chimney, depending upon its configuration. Proposed and presented as a “problem solver” it is in our view a “Band Aid Solution”, and deserving of ridicule.

    As a policy we do not install or service Power Vented Systems. One of our collaborators has in fact “cleansed” his entire 1000+ service customer database of all of these devices. “Don’t need the aggravation” is his comment. Recently however we’ve had two incidents that prompted this discourse. One was “doing a favor” for a dear friend with a hardship to discover a Power Vented Weil-McLain Gold Oil Boiler badly in need of maintenance. The second was an invitation to view a customer’s newly pre-built, purchased home only to discover a local plumber’s handiwork, i.e. a non-Energy Star (new?) boiler with the wrong gun affixed — and a Power Venter.

    Situation #1: This is a typical older period local plumber (and not a very good one) budget installation that has survived 15 years of erratic operation. The boiler piping was so improperly installed in fact as to possibly warrant a future addendum to our blog entitled “Plumbing Guys Plumb, Heating Guys Heat”. The Power Vent required mechanical repair and was by current Building Code non-compliant. Primary Power Vents are typically shoved through the box joist of a building near the heating unit as an expedient, in this case without regard for current Code Requirement that the intake and exhaust of a heating appliance MUST be 12 to 18 inches above the anticipated maximum winter snow level. This one certainly wasn’t.

    Situation #2: This is obviously another corner-cutting special, but new and supposedly to Code. Two counts on this one, i.e. a non-Energy Star Compliant Heating System (built from old stock, separate components?) and the same snow level height venting violation as above. Shame on the Local Code Compliance Officer!

    The Power Venter is by definition an energy consuming device, not only in using electricity to drive a blower, but by also forcing ambient heated air out of the structure to induce draft and cool down the exhaust for expulsion. The resultant negative pressure on the building pulls external (cold) air into while driving already heated air out – a “double whammy”. The argument could be made that in a modern, “tight”, energy efficient home the Power Venter air supply should be external for functional operation.

    By specifying modern pressure-fired or “condensing” heating systems the need for the Power Venter is gradually going away, thankfully! There is no longer a need for a chimney, technically speaking, unless it is convenient and likely pre-existing. Replacing it is either low temp plastic piping on “condensing” gas or concentric metal venting on oil appliances for both combustion air intake and exhausting.

    Note: In some existing cases there may be the opportunity to upgrade with a pressure-firing gun to do away with the powered venting device. Consult with your heating engineer or a well qualified technician.

    In summary, comments to the heating system customer.

    1. Older and existing homes with Power Venters:
      • If you’re buying – beware! Your system operating cost will be higher in utilities and maintenance.
      • If you’re upgrading – factor the Power Venter going away and substituting a high efficiency pressure-fired or condensing system. A “win-win,” in both fuel and operational efficiencies.
    2. New homes:
      • If buying, a Power Venter should not be there. If it is, asks the hard questions. Check your Codes.
      • If specifying a new home, use your Power Venter Eraser. You’ll never regret it.