• Tag Archives AFUE
  • HYDRONIC (FHW) HEATING OPTIMIZED – “Going Back To Nature?”

    A primary tenet of Industrial Engineering is: To properly justify a process change you first optimize the existing process, then define the proposed process and make your CBA’s (Cost-Benefit-Analyses) for both. From weighing these you will then derive your best course of action. Speaking from painful experience as a Manufacturing Process Engineer, you will make this mistake only once. Somewhere in a dark corner of a semiconductor facility (or hopefully a scrap pile) lies my personal ill-advised, sophisticated process equipment humiliation!

    The makings of similar embarrassments are appearing within the hydronics heating industry. Hydronic component suppliers can be placed into three primary groups: boiler, distribution and radiation providers. They correspond to the three basic elements of the hydronic heating process. Component suppliers define the scope and applications of their products within a heating system, but that’s all. History and physics now become excellent teachers.

     A century ago there were two competing water-based energy heating methods, Gravity Hot Water and Steam. Both were based upon the natural (gravitational) convection attribute of water in the liquid or the vapor state, respectively. Energy distribution from a boiler to radiation required no external energy, only variation of the fuel supply ….. more heat, more fuel. Powered burners and thermostats were added for control. Pumps (circulators) doomed gravity water by adding zone management while reducing costs. Thus the modern hydronic heating system evolved.

    I’ve had the benefit of “playing with pipes”, beginning as a teenager within our family heating business for over 65 years while pursuing a paralleled hi-tech engineering career. (You can’t raise ten kids even on an engineering day job.) So while doing hydronic work “on the side”, so to speak, hydronic evolution followed me. My “engineering hat” always questioned why natural convection shouldn’t be an asset rather than a flow-checked nuisance. The old “gravities” were so simple!

    Post-engineering “non-retirement” provided time to aggressively play with hydronics. My “motor head” also makes me analogize heating systems with automobiles, i.e. the boiler being a pure “heat engine” with air, fuel and ignition for example. So when the delta-t circulator came along, there’s the “automatic transmission”. Now what can we do with the drive-line (distribution)? Can we re-evolve the Model T Ford car as a hydronic “Model Delta-T Appliance” by incorporating natural gravity convection into delta-t distribution? Well, we can and we have …..

    The old Gravity Heating System featured a large boiler, proportioned larger piping and radiation, typically all cast iron and pipe. They were skillfully defined and installed, used no distribution energy and lasted almost indefinitely, a tough act to follow. Its modern contemporary uses a much smaller (albeit more efficient) boiler, features multiple, circulated zones with smaller piping and radiation. Arguably it trades off fuel efficiency and comfort convenience for some increased distribution energy and “sophistication”.

    The sophistication referred is almost entirely within the distribution element of hydronic heating systematization.This is the consequence of a component-driven marketplace, as prior mentioned. The contemporary build-in-place method of system installations relegates hydronic interconnection of boiler to radiation in particular as “The Plumber’s Playground” wherein there are few rules and little consequence. Every system differs in a similar application, and therefore all perform differently in practice.

    If the objective is to provide overall hydronic system energy efficiency including electrical power consumption, freelancing must be both qualified and quantified in practice. Redefining near-boiler piping to optimize natural (gravity) convection with the boiler and integrating a delta-t circulator to refine hydronic delivery dramatically reduces distribution material and energy usage. Our now-patented “appliance” exhibits a typical 8 to 13 Watts total distribution energy usage while heating, over 90% reduction depending upon the contemporary configuration. Coupled with a high-mass, cast-iron boiler to enhance gravity operation, it also exhibits a thirty-plus year economic and operating life, twice or more that of low-mass, condensing units.

    Further gravity convection enhancement is available within the appliance-to-zone interconnects. The “level & square, pipes everywhere” approach does not fly in a gravity world. Minimized, pitched piping to simple series and split perimeter radiation loops are ideal. Full port valving if necessary and fewest 90° fittings further contribute to minimizing head pressures and thus distribution energy consumption. It won’t win a beauty contest, but it will win the race.

    Our 2,700 sq. ft. personally built (1970) raised ranch home has been our gravity test stand. An indoor wood boiler was convection-coupled to the cast-iron, flow-checked supply and circulator returned 3-zone “oiler” back in 1975. Multi-mode, multi-fuel operation also permitted completely unpowered, manually adjusted flow check wood gravity convection heating. As an example some years ago up here in “Frostbite Falls, NH” we were powerless from a severe ice storm for 10 days. A mere inconvenience for us ….. just feed it wood and adjust the valves.

    We currently have a series of up to six-year installed appliance “Beta Sites” that have now aggregated over twenty-five years service with no system-related calls! Two oil-contamination incidents did occur and last year a power line short-circuit blew out every control on a system. Our appliance is comprised of all standard, domestic trade components, so it was restored within the day.

    Our “appliance economics” haven’t been mentioned but are profound. Very significant complexity, material/labor content reduction and extended operating life vs. traditional architecture eclipse contemporary materials and methods. This observation was similarly but subtly affirmed in the 2019 Annual Boiler Report by several contributors opining that in effect it’s still hard to beat the economics of a well designed and installed cast iron boiler system. Their commentary and our natural (gravity) convection appliance development experience confirm that the existing, i.e. the “pre-condensing” process has yet to be optimized, to our potential peril. But try to find trade journalism and process development efforts to the contrary!

    So, is history due to repeat? That is, will a hydronic “Model Delta-T” displace this industry’s “Carriage Makers”, or will there be yet another technical “skeleton” in my closet?


  • Our Feature Article “BEYOND AFUE TOWARD HYDRONIC HEATING SYSTEM EFFICIENCY” Published In Plumbing Engineer, May 2016

    We are both humbled and pleased to confirm that our Feature Article “BEYOND AFUE TOWARD HYDRONIC HEATING SYSTEM EFFICIENCY” has been published in the eminent Trade Journal “Plumbing Engineer” in its May 2016 Issue.

    It documents our efforts to apply Delta-T ECM Circulators as Dedicated System Circulators in Hydronic Systems. Mercier Engineering is the INDUSTRY FIRST to do so, culminating a three (3) year development and field testing effort.

    We aspire that the Hydronics Industry and ultimately the Heating Consumer may benefit from our work.


  • OIL AGAIN THE “CHEAP HEAT” IN NH — FOR THE SMART BUYER

    When our family entered the NH Oil Heat Service Market 60 years ago, #2 Heating Oil was $0.135 a gallon! It had replaced virtually all other fuels despite poor heating equipment in un-insulated buildings. In these succeeding years we participated in the evolution of heating appliances and fuel preferences. All the while we have witnessed technical development being compromised by economic and regulatory policies. Fortunately recent developments in fuel extraction have overtaken market manipulation and put things back into perspective.

    Referencing our prior Heating Blog entitled “Heating Fuel Selection — From An Engineer’s Perspective” will provide a base to qualify our further arguments. Briefly, physical characteristics of heating fuels, in particular “energy density”, physical state (gas, liquid or solid), processing & handling characteristics predetermine their viability and effectiveness. Understanding fuel properties will guide you into what we can now refer to as “The Perfect Storm” that has developed in our region, and may be applicable in others as well.

    Understanding the difference between “distributed” and “delivered” fuels is paramount. Simply, a distributed fuel is piped or wired to your building (electricity, natural or city gas) while a delivered fuel is physically dropped at your location (coal, oil, propane, wood, etc.). Distributed fuels are typically single-source provided while delivered fuels are openly competitive. Heating oil is the highest energy density liquid fuel within a competitive and somewhat volatile market (until recently) and thus presents the “smart buying” opportunity. We will demonstrate that #2 Heating Oil far surpasses ALL other heating fuels when properly sourced. Yes, including Natural Gas.

    Whether its gasoline, diesel or heating oil there are many participants in the petroleum fuel products market and competition is keen. Note the number of heating oil companies represented in your area. They are like the varied gasoline stations, but on wheels. The only visible difference can be the size of a particular fuel company and its operating area, but the fuel distribution market is changing, and rapidly.

    NOTE: As a matter of policy we do not reveal specific identities of our sources, organizations and participants.

    Here in Northern New England we have an expanding presence of a Canadian-based “vertically-integrated” Refiner/Distributor. Their combined advantages of excess refinery capacity, direct transport & distribution, a weakening Canadian Dollar and lowering feed-stock pricing makes them a formidable competitor indeed. Although we have not researched it, similar current or potential situations could exist in the Mid-Canada-US Region as well.

    As an individual user in a prolific supplier market you have little buying leverage excepting to “gang up” as Buying Clubs, Co-Ops, etc. and purchase aggressively. Only in so doing can you move into the ‘Big Boys Club” and attain “rack pricing” as it is referred. The buying groups are out there, but they vary in scope and effect. Do your homework well, in particular to the terms of affiliation with both they and their subscribing suppliers. Making the leap from “Good Old Joe” my local oil dealer who has “kept me warm” (at a price) can be a daunting one to an unknowing consumer, so let’s put some numbers together to make things more exciting.

    We use the NH-OEP Fuel Prices Page, published weekly and loaded into the NH Climate Audit Calculator (typically updated monthly) as the basis of our comparison. Loading our daily Co-Op #2 Heating Oil Price we obtain the “Price per Million BTU”, then adjust all the other Fuel Unit Costs to equate. To obtain an “apples-to-apples” comparison we use the average of latest generation heating appliance efficiency (AFUE) for oil & gas as 87% and 95% respectively. The resultant Fuel Unit Costs are the equivalents to oil-generated heating energy. The “distributed fuels” (gas & electricity) must be factored to your total bill for actual fuel cost + distribution/services.

    Fuel TypeFuel Unit CostUnit of MeasureHeating Unit EfficiencyPrice per Million BTUBilled Cost MultiplierFinal Fuel Unit Cost
    Coal215Ton7910.92
    Fuel Oil (#2)1.3186Gallon8710.93
    Natural Gas1.038Therm9510.931.3 (Estimated)0.7984
    Propane0.948Gallon9510.93
    Wood126.70Cord5810.93
    Electricity0.036kWh9910.921.85 (Estimated)0.01946
    Wood Pellets144.30Ton8010.93
    Kerosene1.15Gallon7810.92
    Geothermal0.102kWh27510.921.85 (Estimated)0.0551

    Go to the NH Climate Audit Calculator and substitute your own values for fuel cost, efficiency, multiplier (where applicable) to ascertain your personal numbers. Only if we substitute our statewide fuel oil average cost which appears to be affected by “pre-buys” can we even approach a par with natural gas. My how times are changing!

    Looking forward it bares noting that the appliance efficiency differential between oil & gas seems to be closing as well. Selective gas appliance manufacturers are claiming AFUE’s of up to 97% while “oilers” are nearing 90%. While gas is nearing its zenith oil has a ways to go. We are watching recent advances in higher temperature combustion oil burners and initial results with cleaner “Bio-Heat Fuel” as examples. We will advise as worthy.

    Our personal soon-to-be-published efforts applying Delta-T Hydronic Distribution will benefit ALL heating systems. To quote JFK, “a rising tide lifts all boats”. The sailing ahead should be smoother …..


  • 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 while 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 truly universal, multi-fueled 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 UO is also disproportionately the lowest cost per pound (by nearly half) of the three. Just what is the consumer paying for, we wonder? In our development experience increased boiler mass equates to improved system longevity and hydronic performance!

    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 supply functions are integrated into our system package.
    2. Zone interconnection and functionality 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 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, 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 that 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 ECM Hydronic Distribution Technology is key to improving any system’s energy performance, both 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 optimized in our system piping configuration to include fail-safe “natural gravity convection”.
    5. Interconnections between our system zone access points to existing radiation 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 link 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 08/27/2019


  • 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


  • USING A ‘HEATING COST CALCULATOR’ — CAREFULLY!

    A ‘Heating Cost Calculator’ is a very useful tool to compare the costs of various heating fuels. They typically convert each fuel into a “cost per million BTU’s’, the accepted industry common denominator. Additionally they usually allow varying input data to suit your particular situation. All well and good.

    For reference please use the following links to follow this discussion:

    Note: These are NH Sites (our locale). Similar ones should be available in your area, or adapt these.

    The NH-OEP Home Page (first link) has a listing of current average fuel pricing in our area, dated and updated typically weekly. You will note these in the right column table on this page. The values are automatically downloaded into the Heating Cost Calculator (second link) in the Fuel Unit Cost column. The Heating Unit (assumed value) Efficiencies are displayed and the net Price per Million BTU displayed. Very nice.

    Now you can ‘play the numbers’, selecting only those fuels of interest and availability, their local costs by solicitation, and applying your current and proposed heating appliance efficiencies. If only it was this easy.

    Unfortunately both of these variables (Fuel Unit Cost and Heating Unit Efficiency) are not so clearly definable as we would assume. Let’s look at each one.

    Fuel Unit Cost is the cost per respective unit of measure for that particular fuel. (A Gallon of Oil, A Cord of Wood, A Ton of Coal, A Therm of Natural Gas, etc.) We assume that it is the cost at your door, in your tank, through your pipe, etc. This is not necessarily so, particularly depending upon the type of fuel.

    We must make a distinction immediately between a ‘DELIVERED FUEL’ and a ‘DISTRIBUTED FUEL’. A ‘Delivered Fuel” is one that is physically transported to your door vs. a ‘Distributed Fuel’ that is ‘piped’ through an external network. Natural Gas and Electricity are ‘Distributed Fuels’, the others are not. So why the distinction?

    Distributed fuels are subject to other charges beyond their ‘unit cost’ and is the prompting for this writing. One of our customers is seasonally forwarding his Natural Gas billing that includes:

    1. The Cost per Therm, the number of Therms and the extended cost. (His ‘Gas Bill’.)
    2. A Minimum Daily Service Charge, regardless of usage.
    3. A significant ‘Distribution Charge’, presumably wear and tear on the pipes(?) (He operates a Weil-McLain Ultra Condensing Gas Boiler and 60 Gallon Indirect Water Heater at 93 to 98% (winter to summer cycles) in an older 3-Bedroom Cape, located in Central NH — about 7,500 Degree-Days, current year.)

    Annualized Monthly Natural Gas Bill Summary: Summer (August) Billing: 55% consumption and 45% ‘other’ charges. Winter (January) Billing: 70% consumption and 30% ‘other’ charges. Estimated Annualized Burden: Approx. 33%

    LESSON: Multiply Quoted Natural Gas ‘Per Therm’ Cost by 1.3 (Winter) or 1.45 (Summer) to reflect the actual seasonal cost per therm!

    SUGGESTION: Get an estimate of annual fuel costs based on projected energy usage from your supplier(s) before commitment.

    DISCLAIMER: We install and maintain Natural Gas, Propane and Oil-Fired Systems and have no personal interest excepting to advise the consumer.

    We have not looked at electricity in this light since we have particularly high electric costs regionally, thus electric resistance heating and heat pumps are not popular in the frozen north. But in it’s case you should back out items like ‘stranded costs’ and the like to get to a true energy efficiency calculation.

    Heating Unit Efficiency is our second variable in the Table and should be entered for your present appliance vs. other options, or if new construction only vs. the various options. How do we do these effectively?

    The new appliance efficiency number is easy. Enter the AFUE (Annual Fuel Utilization Efficiency) percentage stated by the manufacturer. (We presume in selecting powered appliances that you are only opting for ‘Energy Star Rated’ equipment. Link: http://www.energystar.gov/index.cfm?c=heat_cool.pr_hvac)

    What about your present appliance? If it’s fairly new it may have an AFUE value on the Specification Tag or Label. If it’s ‘old enough to vote’, then it’s a different matter.

    Many Heating Servicemen leave a Service Tag that denotes date, service items, notes and an ‘Efficiency’ calculation. You will see Draft, CO2 and Smoke values converted into an ‘Efficiency’. CAUTION! This is a ‘BURNER EFFICIENCY’ value and NOT ‘APPLIANCE EFFICIENCY’ as an AFUE value would reflect.

    To arrive at an Appliance Efficiency for your older system would require converting ‘Exhaust or Stack Temperature’ of the exiting gases and relationships between heat exchanger areas vs. firing rates, etc. This is not the stuff you have available at the Serviceman Level to ascertain the equivalent of an AFUE. These are derived on Test Stands in Laboratories.

    Suffice to say that your Service Tag Efficiency is NOT your Appliance Efficiency. Rule: The higher the exhaust temperature, the poorer the efficiency. As exhaust temps go up, efficiency drops dramatically! We won’t and can’t quote numbers, but look at new appliance specifications and take it from there.

    We trust the enclosed will help you to make better fuel and appliance decisions.

    Last Edit: 5/14/2012 pdm