• Tag Archives Radiation
  • 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 the 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 piping 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 applying natural gravity circulation to the contemporary upgrade. We have seemingly lost any trade skills in managing or enhancing gravity convection. No consideration is ever 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 increasing 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 16 gpm 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 contributes. 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 an old adage? Commentary in the recent 2019 Annual Boiler Report would seem to support our contention.

    Finally, the combination of higher boiler thermal 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 excessive system 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. Trade practices and hence consumer perceptions need challenging. Are we selling parts ….. or performance?

    Perhaps it is time for an engineered “appliance” approach (as ours) to rein in “The Plumber’s Playground”.

    Updated 09/27/2019 P.D.M., Sr.


  • 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


  • 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!


  • FORCED HOT WATER (FHW) HEATING LOOPS – A BRIEF OVERVIEW

    Periodic discussions with Do-It-Yourselfers (DIY’s) prompts us to cover the subject of heating loops (radiation piping) frequently. These are particularly prompted by Steam-to-FHW Boiler Conversion inquiries that inevitably come to “how do I pipe my radiators if I want to use them?” A good time to review distribution piping.

    There are three (3) common variations of heating loops:

    1. The Series Loop – The most common configuration. Piping from one radiation element (baseboard, radiators, fan convectors, etc.) to another in a serial sequence and returning.
    2. The Split Loop (sometimes also called the Split Series Loop) – A larger pipe feeds to the middle of a series loop and supplies water to both halves, returning again by individual pipes or to a larger pipe, closing the loop to the boiler.
    3. The Monoflo(w) Loop – A larger, closed piping loop that continually flows water. Radiation is teed off this “runway” to both its ends, driven by a Monoflo Tee that pulls (moves) water through them by utilizing the “venturi effect”.

    The Series Loop is simple, but maybe too simple. How can you go wrong? Pipe from one radiation element to the next and close the loop from and to the boiler. Problem is, every fitting, foot and rise of pipe = resistance to flow. Resistance equals “head” that must be accommodated by properly sizing both piping and circulators to provide even heating. (You may want to also read our blog onLAZY HEATING ZONES.) The effects can be:

    1. Too small a circulator and/or piping size results in a “lazy” zone – temperature (heat) in the first heating element to the last can drop significantly, providing uneven heating.
    2. Install too large a circulator to overcome this and you risk “hydronic noise” created by over-speeding water. Take care to not create very long-piped zones as a practice.
    3. You inadvertently are loading your electric bill in either case. Longer circulation cycles in a “lazy” one or overpowering in the latter. Size and lay out zones properly.

    The Split Loop by nature is more efficient, requiring less power to move water and lessens the temperature (heat) differential across radiation significantly. It’s also a good way to get out of trouble with a poorly performing Series Loop – as long as it’s not too poorly configured. Strategically it’s also a good choice for future splitting into individual zones. Plan ahead.

    1. In new construction lay out your common feed(s) and return(s) so that you anticipate future lifestyle heating options.
    2. In old construction, re-pipe with feeds and returns to enhance current heating conditions while again anticipating future options.

    The Monoflo Loop is a technique that is currently seldom used due to cost. It takes a little more pipe (and time) to configure and requires a little more circulator to drive the required venturi tee fittings, but if you want nearly simultaneous, even heating – this is it! It is most often found on original or converted cast-iron radiator systems.

    The Two-Pipe, Reverse Return is another method to evenly supply radiators and other convectors. A supply pipe is routed and branched to each convector. Another return pipe is likewise routed and branched to each and back to the boiler. The key is to return flow in the opposite direction to that of the supply, i.e. the first radiator supplied is the last to return. This reasonably balances delivery and lowers head pressure in a properly proportioned supply-return system.

    Which brings us to the major current application for the Monoflo or Two-Pipe, Reverse Return System, converting Steam Radiators to FHW Heating. Re-pipe every steam radiator into a two-pipe supply and return, and drive them either with a Monoflo Distribution Loop or a Two-Pipe, Reverse Return System. These are the only effective ways to even out any radiator-based zone. There’s a lot of water in those radiators! Pipe them into a Series or even a Split Loop and you will appreciate the term “lazy” heating. DIY Steam to FHW System Converters Take Note! The result is well-balanced, even heating with fewer, although more forceful circulator cycling.

    Know your heating loop options and do your technical homework related to pipe and circulator sizing for efficient distribution.

    Author’s Note: This discussion is predicated on contemporary fixed (single or multi-select) speed circulators. The hydronic distribution “ball game” has now totally changed with the introduction of Delta-T ECM Hydronic Circulation. It is applicable to both new and existing installations, providing dramatic electrical along with fuel consumption reductions. We are acknowledged application pioneers of this technology and have recently filed for Intelligent Property (Patent) Protection in the USA & Canada) on our ENHANCED CONVECTION, DIFFERENTIAL TEMPERATURE MANAGED, HYDRONIC HEATING APPLIANCE.

    Last Edit: 09/11/2019 PDM, Sr.


  • ‘THESE ARE THE TIMES THAT TRY MEN’S SOULS’ — AND HEATING SYSTEMS

    Our apologies to Thomas Paine who coined his famous phrase to inspire the American Revolution, but in a prophetic sense it seemingly applies to all things mechanical. This is particularly evident as we are approaching our seasonal, deepening cold cycle. The car doesn’t start, or does so hesitatingly and emits strange noises upon doing so. You resort to a shovel after the snow blower quits, etc., etc.

    Similarly your heating system is working harder and longer to offset Mother Nature’s Global Cooling Cycle, like it or not. So we must “deal with it” as the expression goes. Approaching this from a positive perspective it is also an opportunity to evaluate your heating system’s performance, both the good and bad.

    Obviously we want to monitor the heating system while it is at a peak demand, placing the most severe duty upon it. Mother Nature is fairly cooperative in this respect, and we like to think particularly so in New England, our venue. Deepest cold is typically about a month (plus or minus) after the Winter Solstice (Dec. 21) when we are not fooled by a “January Thaw”. So ultimately just watch the Weather Report.

    The objective must be to determine if the heating system is capable of heating your structure both adequately and reliably at peak (deepest cold) demand. Ideally this exercise would be unnecessary if the system was designed around a heat loss calculation and the characteristics of each room using a Heat Loss Software Program or Tables while using the Meteorological Data for your area. Unfortunately in particularly older dwellings changes have been made not only to the physical structure, but in central heaters (boilers, furnaces), distribution (piping, ducting) and radiation (radiation, radiators, fan units, registers), windows/doors and insulation that have impacted heating both positively and negatively. This is why it is most effective to determine your situation at peak demand.

    Therefore we will look at the central heater (boiler, furnace) cycling and the resultant effect upon room temperature(s). In between these are the heat delivery characteristics of piping, ducting (or both) to achieving the result(s).

    So, on that deep(est) cold January overnight prepare yourself by setting your thermostats to the normal (day?) temperatures (no setbacks — this is a peak load test) and take note of:

    1. The percentage of time that your burner (oil or gas) is firing.
    2. The percentage of time that the furnace fan or boiler circulator(s) operate.
    3. The actual temperatures of each room vs. the area (zone) thermostat setting.

    Note: If you have a steam system, Item 2 is not applicable. The radiator vents are the only adjustment.

    Firstly, try to balance your room temperatures to settings by adjusting register openings, wall or kick space (toe) heater speeds, steam radiator vent settings over a period of hours preceding peak cold.

    1. Can you bring all rooms up to temperature? Within a zone (thermostat) area or total? Capacity issue — see further.
    2. Can you balance each room? If not note the deficiency by room for future correction.

    Secondly, monitor your distribution components (furnace blower or boiler circulators) that are related to these room temperature observations (excepting steam).

    1. If the furnace blower (FHA System) is running constantly and temperatures are not met it is likely that the blower speed (heat delivery rate) must be increased. If it runs intermittently with significant “rests” between cycles, there is likely a burner, air temperature or other distribution capacity issue. See further.
    2. Similarly, in a boiler (FHW System) observe the circulator operation per zone and overall. If the zone or area circulator runs continuously there are three possibilities:
      • The zone radiation (capacity) or piping is undersized or incorrect.
      • The zone may be air-bound and need “purging”, i.e. water-flushing air removal. Check for incrementally cool or cold registers.
      • The circulator is incorrectly sized (too small).
      • The boiler water temperature is low (unsustainable). A boiler delivery issue. See further.

    Thirdly, observe the burner cycling times at peak demand in light of the prior distribution issues.

    1. If the furnace (FHA) gas burner operates virtually continuously, the unit is at capacity (undersized). Note: On gas units the firing rate is typically fixed or self-regulating.
    2. If the furnace (FHA) oil burner operates less than continuously (particularly less than half), the unit is probably over sized.
    3. If the boiler (FHW) oil burner operates virtually continuously, the unit is either at capacity (undersized) or if not the firing rate should be increased as permissible toward requirement. Note: On most boilers the operating temperature may be increased somewhat to gain some capacity, subject to functional limits. Trained Technician recommended.
    4. If the boiler (FHW) oil burner operates less than continuously (particularly less than half), the unit is probably over sized.

    Summarizing, this is a layman’s exercise to provide working data for a qualified Technician to pursue. There are other diagnostic methods, particularly in temperature measurement of FHW piping distribution to optimize your empirical determinations. A degree of risk is involved and should be deferred to a qualified Technician. You have done most of the leg work, isolated the issues and become an informed client. Let him take it from there.

    Meanwhile, enjoy the rest of our winter.