• Tag Archives Piping

    Having now maintained our own Interior, Integrated Wood & Oil Heating System since 1975 and more recently integrating Outdoor Wood Boilers to our Weil-McLain FHW Heating Systems,  we are motivated to pass on some of our observations.

    (Note hyperlinks within the document.)

    Disclaimer: We are exclusive Weil-McLain Heating Designers & Installers here in NH only (thus far). We do not nor have not specified, sold or initially installed any interior or outdoor “Solid Fuel” (Wood, Pellets, Coal, etc.) Boilers. Our participation has been to occasionally help out a customer integrate these products with our Weil-McLain Hydronic Heating Systems per our personal experience. Included has been converting Steam Boiler Systems to FHW and conjoining these systems.

    Note: We offer as an option full-size fittings (plugged) at our boiler supply and return points to integrate other boilers. Specify at ordering.

    The recent popularity of Outdoor Wood Boilers in particular has prompted many inquiries and discussions on our part. They seem however to neglect the interior-located solid fuel boiler in the scope of options. Each of these have distinctive attributes that both complement and complicate their integration and operational effectiveness.

    Inside or outside? That is the (first) question and may likely be answered by The Regulators (Zoning, Fire and Insurers). Specifically to wood/coal boilers:

    1. The Local Zoning Code will define permitted use and location parameters. (Outdoor Boilers are particularly vulnerable to NIMBY (Not In My Back Yard) and more specifically regulated.)
    2. The Fire Codes usually reference both, but are tough on Interior Boilers.
    3. Insurers (risk takers) then determine how much it is going to cost you to save money. Again, interior boilers take the major hit, especially if it is the primary energy source.

    Note: The delineation is between Gas/Oil-fired Power Burner Heating Systems and Solid-Fuel Fire (Coal/Wood, etc.) Systems. Insurers will usually bend for Automatic Stoker-fed Coal and Automatic Wood Pellet Systems with a two-week continuous-feed fuel storage supply. Check your local codes and insurers, however.

    At the risk of oversimplification and generalization we offer the following:

    TypeFlueLoop LengthLoop LossesStandby LossesEfficiency (Overall)
    InteriorReq'dShortLowLowModerate to High
    OutdoorN/ALongHighHighLow to Moderate


    Any Interior Wood/Coal Heater REQUIRES A DEDICATED CHIMNEY FLUE! Flue quality must also be considered to support a continuous fuel fire. A “sometimes option” is to convert the primary powered burner (gas/oil) appliance to a “direct vent” device vs. the additional flue construction cost. Check it out.
    The Outdoor Wood/Coal Boiler has its own integral exhaust stack. However it is not unusual to see vertical stack added, sometimes up to 20 ft. to improve draft or smoke dissipation conditions.

    Loop Length:
    An Interior Wood/Coal Boiler can be readily be coupled to a FHW System, given flue location options. Interior Boilers are typically like-pressurized and therefore operationally compatible.

    An Outdoor Wood/Coal Boiler is typically “Zero Pressure” to simplify construction, ease of operation and complexity. This comes at a price with a continuously-powered, “high head” (flow resistance) system loop to the FHW System using a tough circulator. An in-line Heat Exchanger is required to mate the pair. Significant heat losses occur as well.

    Loop Losses:
    Interior Wood/Coal Boiler Loop Losses are typically dissipated to the ambient surrounding area and usually indirectly contribute to the heating of the structure.
    Outdoor Wood/Coal Boiler Interior Loop Losses are as prior, but Exterior Losses are very significant! (We have a system with over 400 feet of high quality, insulated two-pipe, buried down several feet. You can readily observe the reduced/absence-of-snow line path.) You must further isolate the “Zero-Pressure” Outdoor water from the interior “Pressurized” water using a “Plate-To-Plate” Heat Exchanger System with controls & circulators. This system contributes some heat to the ambient area, however.

    Standby Losses: (Defined as energy losses between heat demand cycles.)
    All Interior Boilers dissipate energy between cycles to the ambient and incur flue losses (heat up the chimney). The chassis and piping energy is generally accepted to be contributing to the heating environment positively excepting during the non-heating season.

    All Outdoor Boilers lose significant energy both from their chassis (never any snow on them) and their exterior service loop if circulation is not inhibited with demand. All this is lost energy by definition.

    Efficiency (Overall):
    Albeit being an empirical determination, the relative efficiencies of interior vs. outdoor boiler systems will be effectively higher due to their placements (in heat value areas) and reduced loop and standby losses. Thus the terminologies assigned and relationship to each other.

    Note: We are not addressing the Heat Generation Efficiencies of any boiler products in our discussion, these varying by configuration(s), but only their overall performance by type. Open the NH Climate Audit Calculator (Excel Doc). It’s a useful tool to both qualify and quantify your options by “playing the numbers”. Our “trick” is to calculate the “Cost per Million BTU” for a selected fuel, then adjust other fuel costs to equal your selection MBTU value. Remember to adjust your fuel appliance efficiencies if known or use the defaults. The resultant is a great “apples to apples” economic comparator!

    Operational Observations:
    Further observations of field operation leads us to believe that many outdoor boiler users fire them virtually continuously, incurring very poor fuel utilization, during low heat demand periods. Perhaps there is a continuing need for DHW (Domestic Hot Water) Generation without a storage means provided, or an unwillingness to build a new fire.

    We have evidenced outdoor wood systems consuming 11 cords of wood that in our humble opinion should be consuming no more than 5 cords with an interior boiler, 45% of the outdoor unit. Granted this is a very heuristic and unqualified determination, but yet an indicative one.

    Whatever the case, if one presumes to maximize his fuel utilization the household must adapt to the characteristics of the solid fuel fired system. “Showers-On-Demand” will likely require a generously sized Indirect Water Heater (Super-insulated DHW Storage Tank) to accommodate this lifestyle. Otherwise an incremental or even seasonal fallback to the gas/oil-fired system may be necessitated, and desirable.

    There is a tendency of auxiliary wood/coal users to “over-engineer” their systems. A prolific use of circulators, relays and controls result. We would respectfully suggest that exploring the use of Taco® Delta-T ECM Circulator Technology would benefit energy management. Further, employing Taco® Zone Sentry Valves with these permit some emergency (no power) gravity heating on interior boiler systems.


    1. Outdoor Wood Boilers appeal to users who have larger fuel demands, an abundant, low-cost supply of particularly cord wood, time and resources available to process it! (As we say: “Wood warms you twice!”) Higher equipment installation costs and poorer total fuel efficiency is a definite factor in their consideration.
    2. Outdoor Wood Boilers in particular require continuous electrical energy for combustion and distribution. No Power — No Heat! (Or it’s own a generator, too.)
    3. Interior Coal/Wood Boilers are operationally more desirable, but regulatory influences must be qualified and satisfied.
    4. Installed Costs of any dual-fuel system are substantial. To minimize this and achieve predictable performance, use of a qualified technical resource is recommended. Utilize a “system guy” and not just a “tech-sketch” provided by the boiler salesman.
    5. Not maintaining ideal and consistent heated water delivery in any system takes its toll on equipment, in particular circulators, through very long duty cycling.

    Our Personal System and Performance Data:

    Referencing our Blog on our personal system, we offer the following:

    1. Operating as an oil-only system between 1971-1975
      • Annual Fuel Oil Consumption: 475 Gallons x 140KBTU = 66.5MBTU/Yr @ 85% Efficiency = 56.5MBTU/Yr. Net Usable Energy
    2. Operated as a wood-only system between 1986-1995 (9 yrs.)
      • Annual Wood Fuel Consumption:  4-1/2 Cords average x 20MBTU/Cord = 90MBTU/Yr. @ 60% Efficiency = 54MBTU/Yr. Net Usable Energy
    3. Operating as a dual fuel system otherwise between 1975-1985 and 1995 to date. We have been using only a modest amount of wood in recent years, restricted by wood fuel costs and time constraints.

    2016/2017 Full Heating Season: 460 Gallons of Fuel and 1+ Cord of Wood + combustible paper & other waste, as available.  (Admittedly approximations.)
    10 Room Single Family Home, Built 1970, Heated Area: 2,016 Sq Ft
    3-1/2 Zone, Programmed T-Stats, Coupled FHW Oil and Wood Boilers. DHW Immersion Coil on Oil Boiler. Planned Upgrade: Large Indirect Water Heater (HTP SSU-80) for DHW to permit less low/no heating season boiler cycling. TBD.
    Annual Degree Days: 7,500 Average (SW NH)


    Dual-fuel and in particular interconnected FHW boiler systems offer a good heating option, given they be properly configured and operated. We have a long ways to go however to inform and guide customers in their economics, application and execution. It is our hope that this document is of some help toward this end.

    Author’s Note: Updated 10/13/2017


    Making that wood or coal fired boiler perform well when coupled to your gas or oil fired FHW heating system can be a challenge. They just operate differently. Only by knowing their characteristics and utilizing them to advantage can we affect positive system behavior.

    An automatic, powered FHW system necessarily attains a high water temperature (just below boiling) during heat demand for heat transfer efficiency. The heating system is pressurized (like your automobile) to enhance circulation and increase the boiling point. Controls adjust burner operation to compliment demand levels (instant on-off). Your radiation is sized to compliment its heat generation capability.

    A coal or wood boiler has a far different firing (heating) profile. Their fuels have “burning stages”, typically ignition, charcoaling (wood) and gasification. Each stage increases combustion temperature (and efficiency). Maintaining a fire necessitates replenishment (mixing) of new fuel, continually changing the heating profile. This can be moderated and controlled in degree by sizing, i.e. wood pellets vs. split firewood or rice coal vs. chunk. In either case, the fire is modulated by air and draft control.

    Note: Exterior Coal and Wood Boilers are typically “Zero Pressure”, necessitating a water-to-water heat exchanger to couple to the typical 12-15psi FHW System. This will require an additional controlled, properly sized and powered circulation loop.

    The major control element of an integrated system is the FHW Boiler Master Aquastat, controlling powered system temperatures and burner operation. It is typically designed to operate in a narrow and high temperature range for efficiency. This must be widened to accommodate the fluctuation in solid fuel delivery or your burner will be cycling often and shortened cycles. (Tough on equipment as well.)

    You will have to check the specifications of your Master Aquastat as they vary widely with your system type. Briefly,

    1. If you have an Immersion Coil to generate DHW in your boiler, your Aquastat is a “Triple Action” or “Ranging” Type that maintains temperature with a modest, adjustable temperature differential.
    2. If not, your boiler provides only heated water for area heating of your home or structure. It has (or should have) a “Cold Start” Aquastat that only fires the boiler when heating is required. Otherwise the boiler cools down between cycles, approaching ambient temperature. Additionally,
      • Older systems will likely have narrower, fixed differential controls.
      • The newer, high efficiency boilers will have adjustable or programmable digital controls. Check specifications again.

    Your Master Aquastat should have a fully adjustable temperature range, wide, adjustable differential(s) and mode switching to compliment coal or wood boiler interaction. We employ the Hydrolevel Model 3150 Universal Aquastat exclusively:

    Specifications: http://www.hydrolevel.com/pages/new.html

    Installation: http://www.hydrolevel.com/pages/pdf_files/HydroStat.pdf

    It does everything, and well. You can “range” up to 30 deg F on the high and low ends, inhibit burner within high range and cut off at low limit (mode). Nice, visible display!

    Check one of our site photos for interfacing and general piping details (powered boiler).
    Link: http://www.merchantcircle.com/business/Mercier.Engineering.603-588-2333/picture/view/2875310

    This provides your basic interface, but more is required, particularly hydronically.

    Particular attention must be paid to the operational habits of your coal or wood boiler, particularly in ultimate temperature control. Can you fully fuel it when the boiler is red hot and walk away unconcerned? If over-firing is undesirable, you must dissipate this excess energy somehow. Options:

    1. A “Dump Zone” – Actuate heating zone(s) automatically through an in-line high limit “make-on-rise” Aquastat. They can be normally or optionally heated zones. Result is an overheated house, basement or garage, or all. Wiring this option can be tricky, however. Watch your control wiring. Add isolation relays if in doubt.
    2. A “Dump Tank” – Configure a storage tank in parallel with the feed lines to the FHW Boiler. Depending upon your physical layout and attributes it could also be behind and near the solid fuel boiler to act as a direct “Tempering Tank” to it. Between the boilers it can function as extra heating capacity, in degree. Again, take care with your circulator circuit and temperature sensors.

    Note: Reading our blog entitled OUR UNPOWERED FORCED HOT WATER (FHW) GRAVITY HEATING SYSTEM may be of some help in this regard, where applicable. Employing gravity elements used in our personal system takes some expertise and effort. BE CAREFUL!

    To further control inhibiting the burner at a lower temperature than the 3150 ranging allows may require placing an immersion style (where boiler provision is available) or a “strap-on” style Aquastat on the inter-boiler loop. This would be a “make-on-rise” Aquastat configuration.

    Another option is a manual one – placing a switch in series to the burner wire and located conveniently. Just don’t forget to turn it back on before you go on vacation!
    Operation requires “tweaking” of controls and in particular of temperature and differential settings. Heating demands vary widely with external temperature, lifestyle patterns and solid fuel firing schedule. If you still find that your FHW Boiler is cycling too often despite your best efforts, look at your total boiler water capacities.

    EXAMPLE: We have a client who is attempting to supplement in a larger home using a Chunk Stove with an internal water coil. The system has such low water capacity that if he delivers water at a reasonable heating temperature it is short cycled. Water temperature is either too cool, correct for a short period and tripping the “Dump Zone”. The quick patch is to install a “Dump Tank” with circulator-loop controls to accumulate energy along with aggressive firing of his chunk stove. Even then it will only be modestly effective – unless he wants to fully occupy himself in the basement.

    We alluded early on to radiation capacity as a concern. Radiation is designed to operate at a high, normal FHW heating temperature of 180-190 deg F. Lowering this temperature necessarily lowers heat delivery significantly. If your FHW System was slow to warm your home, it isn’t going to get better with a solid fuel boiler’s varying, if not lower delivery temperatures!

    Newer homes we find are radiated so closely to peak cold expectation as a cost constraint that a solid fuel boiler supplement may be disappointing. Older home FHW Systems on the other hand tend to be better radiated by design – and – home energy improvements have reduced their heating demands, effectively increasing radiation capacity! Their original boilers if still in use also exhibit this over sizing effect, coupled with the earlier tendency to oversize them more aggressively by design.

    So, if you are having difficulty maintaining warmth you have a few options:

    1. Increase the water capacity of your system with a “Dump Tank” to hopefully provide a damping effect against deep day/night fluctuations.
    2. Qualify pipe sizing and routing compliments boiler capacities.
    3. Verify that capacity of your solid fuel system is adequate.
    4. Increase the radiation capacity of your home, proportionately for maximum comfort. You can always close registers to cool selective areas, but not to increase others.

    Note: Use a Heat Loss Calculator to qualify items 3 & 4 above! (See our Blog.)

    We have purposely omitted piping and electrical diagrams from our discussion. There are just too many factors and system configuration details to present generic solutions. This is where a qualified heating technician or engineer should assist you to obtain a successful outcome.

    An integrated system while offering a likely significant benefit in heating cost reduction does present its own operating characteristics:

    1. Circulator run time is significantly increased due to lower average system temperatures. Expect a modest increase in electric cost with more wear and tear on circulators and controls over the longer term. Keeping a spare circulator on hand is probably a good move for a DIY.
    2. If you use Setbacks with a Programmable Thermostat, be prepared to adjust not only the setback temperature but the times to “lead and lag” for comfort. Experimentation here.
    3. If you don’t utilize the wide differential range of the recommended Master Aquastat and install a second Aquastat to inhibit your FHW Burner at a lower temperature, you may exhibit significant heating lag. Adjust your temperature set point upward to moderate this condition (or listen to the “cold blooded” complain).
    4. Exterior Boilers in particular are vulnerable to power outages. A small backup generator in any case might be a judicious move.

    Hopefully this introductory discussion will help toward this end. You may also wish to read our other blogs to fill in more detail and explanation.

    Last Edit: 10/10/2012 pdm


    Periodic discussions with Do-It-Yourselfers (DIY’s) prompt the subject of heating loops (radiation piping). Particularly Steam-to-FHW Boiler Conversion inquiries inevitably ask “how do I pipe my old radiators if I want to keep them?” A good time to review distribution piping.

    We must preface by stating that the following traditional heating loops are the simplest and most efficient means of heating a structure. They lessen piping lengths and head pressure (flow resistance), minimizing material & labor costs with less circulation energy required. Beware the contemporary plumber or heating installer who claims that all his additional “pretty piping” and controls increase performance. They absolutely do not!

    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 a “venturi effect” pipe tee.

    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 through the required venturi tee fittings. But if you want nearly simultaneous delivery and even heating – this is it! Most often found on older baseboard or converted cast-iron radiator systems.

    Additionally a TwoPipe, Reverse Return Method is another proven way to evenly supply larger radiators or 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. FIFO = “First In, Last Out. This reasonably balances delivery and lowers head pressure in a properly proportioned supply-return system.

    We finalize with the major current application for the Monoflo or Two-Pipe, Reverse Return System, converting Steam Radiators to FHW Heating. You MUST re-pipe every steam radiator into a two-pipe supply and return, and then 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 large 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 soon appreciate the term “lazy” heating. So, DIY Steam to FHW System Converters in particular take note! The result is well-balanced, even heating with less, 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. All in the quest for Simple, Durable and Efficient Hydronic (FHW) Heating.

    Last Edit: 10/22/2019 PDM, Sr.


    In our preceding blog we addressed the subject “Plumbing Guys Plumb, Heating Guys Heat” to emphasize the need to employ complimentary skills in heating installations.

    Ironically, within a week of publishing we received a call from a new client complaining of “loud banging and water spurting out of the radiators” in a home they were to rent. A complimentary assessment and surprise followed that prompts this follow-up article.

    Apparently ten years ago a new, small, but adequate “plumber’s” steam boiler was installed to replace the original, large coal or wood boiler in the old farmhouse. The plumber exhibited good workmanship in “stretching the pipes” using copper and fittings to connect the new boiler, but obviously had no comprehension of steam heating, didn’t refer to the supplied Installation Manual requirements — or both. Explanation.

    Old Steam Heating Systems featured large water capacity boilers likely originally fired by coal, wood, etc. and necessitated by the continuous, lower temperature fires they utilized. The radiators, properly sized and positioned, provided nice, efficient, humidified and comfortable heating with that little hiss of venting steam. These boilers however were terribly inefficient, requiring firing attendance and water replenishment while consuming large quantities of cheap fuel.

    Conversely, new high-efficiency, intermittent and higher temperature fired (gas or oil) boilers are necessarily much smaller to provide the same output. Therein lies the problem. A ten-gallon boiler now replaces a fifty-gallon unit. All this size and water dampened and regulated the steam output of the “Old Dragons”. Now control has to be introduced to compliment these smaller “steamers”. (Also see our “Upgrading Your Steamer” Blog.)

    Every Steam Boiler Manufacturer in his “Installation Instructions” Manual details a boiler piping configuration known as “The Hartford Loop” and Equalizer Piping, whether so-called or not. Named after the Hartford Insurance Company that funded its development, it tames the modern steamers by preventing the overheated, split and sometimes exploding boilers resulting. Rather than expounding upon the Hartford Loop and Equalizer we refer you to an excellent article on MasterPlumbers.com entitled “What you should know about Hartford Loops” by Dan Holohan. It is well written and thorough.

    Now back to our misbehaving steamer. Walking into the home, it sounded like “The Anvil Chorus” being played by atonal blacksmiths with three-pound hammers both in the basement and on the radiators. Hot water spewed out of all the radiator steam vents even to the second level and all the floors were subsequently blackened by stains near them. Downstairs the boiler was surging steam internally, forcing condensate (hot water) up the supply pipes and back-flushing into the returns. Flash evaporation caused by driving steam through hot water created a cacophony of sonic noise throughout the basement. No water level was detectable in the boiler sight glass. The automatic water feeder and low water detector had apparently been fooled (thankfully) into overfilling and nearly flooding the boiler. This is the only thing that has saved this boiler (thus far) from destruction. (These sleepless tenants are the third in the past six months in this place — can’t imagine why!)

    This is undoubtedly the worst plumber-error installation we have seen to date. Most are more subtle with lesser impacts. It serves though to emphasize that utilizing appropriate resources is paramount to successful and ultimately safe heating system installation and operation.

    Steam system questions seem to predominate in our inquiries. There obviously is a deficiency of skills and understanding of steam heating, even within the heating trade itself. Hydronic (FHW) Heating has long ago overtaken Steam as a heating medium, whether wholly justified or not.

    Specifically addressing your steam heating system installation and operation, question the aggravations that may arise such as noise, water consumption, piping leaks, heating uniformity and fuel consumption. Anything beyond warm, comfortable heating with that little hiss from the radiators is abnormal. Enjoy your steam heating benefits!


    You have doubtless noted the “Plumbing & Heating” Logos on Trade Vehicles. Both disciplines are related, specifically to FHW (Forced Hot Water – Hydronic) Heating Systems, but not necessarily synonymous. They share similar tools and some materials, but not the same techniques — and it shows!

    At the risk of categorization and classification we can readily identify with surety who installed your heating system, i.e. a plumber, your brother-in-law, a DIY (Do-It-Yourselfer) or a heating specialist. The levels of knowledge, application skills and techniques define the end product, and its net performance and efficiency. To quote the axiom “the devil is in the detail” certainly applies to this observation and how the details affect system operation, efficiency and maintenance.

    Ideally you want a FHW System that is finely tuned for performance, notably:

    1. The highest economically efficient energy producer (boiler)
    2. Hydronic components selected for operational efficiency and life cycle cost
    3. Circulation and radiation options complimenting your structure and lifestyle
    4. Complimentary, efficient DHW (Domestic Hot Water) Generation
    5. Optimized hydronic distribution (piping) and zoning

    Prefacing our remarks, do not do a thing until you know your aggregate needs for heating energy! There is no excuse or recovery for not knowing this up front. A Heat Loss Calculator (see other blogs) is not outside the capability of a homeowner or DIY’er, not to mention the professional. Also the Calculator is a great tool for playing energy improvement scenarios prior to making money decisions. Git-er-done!

    Boiler sizing is usually our first observed misapplication, virtually always too large for the current application. In fairness to the original installer and dating of an aging boiler, the existing structure and boiler inefficiencies were a factor as well, along with over-sizing practices at the time. Unfortunately the resultant of subsequent energy improvements and old indiscretions combine to make the boiler now substantially over-sized and an even greater stand-by loss energy robber. (See other blogs)

    Additionally there are the “plumber’s boilers”, as called in the trade. Same so-so boiler, same techniques for decades. Even this “old dog” has had to learn some “new tricks”. The new Triple-Pass (Oil) and Condensing (Gas) Boilers offer us very efficient new tools — with new rules!

    Near-Boiler Plumbing (includes the boiler and Distribution (Zone) piping) is the next focus area. Indicative poor practices are:

    1. Bushings in boiler supply and return outlets, reducing outlet piping sizes at the peril of high stress and corrosion prone fitting failures at the boiler. (We use Heavy Series Nipples and Reducing Elbows, Tees or Couplings to avoid this structural risk.) Such failures are so much fun!
    2. Continuously hard-piped (supply and return) manifolds, with too many fittings and no repair or boiler removal provisions. (More fun!)
    3. Extended length manifolds with high cantilevered loads (weights), sometimes anchored to the floor, wall(s) or overhead construction for support. (Here’s our “Compact Steel Hydronic Header” – Patents Pending that addresses this problem)
    4. Poor (or no) manifold flow proportioning.
    5. Lowered return manifold and piping.
    6. Lots of copper piping vs. iron.
    7. Misplaced, excessive or insufficient valving.
    8. Circulation and/or Zone Valve application and placement.

    The added Indirect Water Heater installation is virtually always “hacked”, i.e. however neatly installed it is thermally compromised. Too much, inappropriately sized, and somewhat under-insulated piping usually stretched from existing boiler manifolds contribute to unnecessary seasonal stand-by losses. (Our “Secret”: We “close-couple” Indirect Water Heaters directly to the first-off-the-boiler fittings to minimize heat loss. The system manifolds are unheated seasonally, save a little convective heating under the insulated riser piping.)

    The guy who has to service a boiler knows best where to place service components (water pressure regulator, circulators, valving, relays, service switch or clean-out accesses)! We position all of ours within an arm’s reach for servicing efficiency.

    A point to ponder: Every extra foot of piping, every elbow, foot of water head-height and gallon of water, through every fitting and valve consumes more energy to accomplish the heating task. Distribution efficiency is totally disregarded by every contemporary hydronic (FHW) heating system installer!

    Example: A past “boiler swap” in an apartment house yielded an excess of 35 feet of copper pipe lengths, many shorter “cuts”, fittings, etc. The new Triple-Pass Weil-McLain Ultra Oil Boiler fires @ 70% of the prior 30 year older Weil with new, appropriate wet-rotor circulators uses 40% less fuel and supplies endless DHW through an 80 Gal. Indirect Water Heater. Every little bit counts — and counts up!

    If it’s any consolation, many of the “old dog” plumbing guys are closing out their careers. Now we other “old dog” heating guys that are determined to continue adapting and applying our skills and experience using the new heating tools have our days in the sunlight. Problem is, we have a lot of consumer educating to do. Hope that jabbing our plumbing brothers a bit makes this ever more apparent.

    To emphasize this point look at our Enhanced Convection Delta-T ECM Hydronic (FHW) Heating Appliance – Patents Pending (USA & Canada) and our supporting website www.BoilersOnDemand.com.

    If our fellow “Plumbing & Heating” Tradesmen need assistance in efficiently applying the latest in hydronic distribution technology, perhaps we can help them ….. or you, the consumer directly with America’s First Hydronic (FHW) Heating APPLIANCE™!

    Updated 08/01/2018 P.D.M., Sr.


    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.