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  • THE HYDRONIC REVOLUTION – The Intelligent Delta-T ECM Circulator FHW System

    We have witnessed many technological breakthroughs in the past fifty (50) years or so. My engineering career began manufacturing the first transistors, through integrated circuits, personal computers, parallel-processing supercomputers and their logical applications. Now witness the plethora of personal, mind-bending “high-tech” devices available to almost everyone. Similarly there are advances in energy, transportation, communications, etc. that will derive our future.

    OK. So what’s this Hydronic Revolution? Hydronics is the use of water as a medium in heating (or cooling) systems. Thus a Forced Hot Water (FHW) System is more correctly a hydronic system. As simple as they seem, Hydronic Systems need to be carefully designed to maximize their performance, both heating-wise AND electrically! Unfortunately most applications are incorrect hydronically and virtually all electrically, nor can they be using dated components and methods in particular.

    Heated water generated by a boiler must be pumped through “radiation” (baseboard, radiators, heaters, etc.) at an idealized rate to suit the heating demand. Pump it too slow and you have a wide temperature variation and “lazy” performance. Pump it too fast and you waste power and can create hydronic circulation noise. In both cases you waste energy, particularly electrical. The pump (circulator) either runs too long, or too hard.

    Enter the Variable Speed “Delta-T” Circulator some years ago. It measures the input and output temperatures of radiation piping and adjusts its pumping rate (speed) to maintain a “Delta-T” (temperature differential), usually set to 15-20°F with further adjustment to suit varying applications. It was a great advance from Taco® Comfort Systems, the premium American Hydronics Manufacturer with variants produced by others (U.S. & Foreign). It has never really “taken off” though, finding a niche in process control, radiant heating and other problem solving but little else to date ….. until now.

    Taco® has again “upped the ante”, and really upped it this time! Their newest offering, the Taco® VT2218 00e Series Delta-T ECM (Electronically Commutated Motor) Circulator is a marvel of Applications Engineering. An “Intelligent Circulator” is now an apt, if not a modest description. Kudos to our fellow engineers!

    Referring to the Taco® VT2218 00e Series Circulator Specification Sheet you can appreciate the sophistication of this device, and its flexibility to suit varied applications. It can do so much in fact that we must limit our discussion to its application as a simple Delta-T system circulator, its predominant application and the objective of this blog.

    Of equal or greater importance is what is not explicitly referenced in the Taco® specifications, how it attains its intelligence. Simply stated, the circulator logic “learns” its application pattern over a period of time, placing it in memory and executing it in the successive period. While executing, it continuously “observes” the pattern variations and adjusts its memory accordingly. Thus your programmable thermostat(s) cycles and heating load variations can be patterned and thenceforth satisfied efficiently.

    Similarly, observing pattern changes such as the length of a heating demand allows the Taco® VT2218 to empirically determine the relative outside temperature, emulating an Outdoor Temperature Sensor Option function. Being a passive measure, it would lag the correction time of an outdoor sensor, but to what overall effect?

    Utilizing a single system and/or distribution circulator such as the VT2218 Delta-T ECM vs. multiple fixed-speed circulators does require controlling individual thermostat demands via Zone Valves. Here again Taco has met the challenge. Again a little background is helpful.

    Taco® is the undisputed giant of the residential hydronic zone valve market. Their “Heat Motor” Zone Valve has dominated for decades and is available in most hardware and “box” stores as is their Model 007 Circulator. The combination of these power and control most residential hydronic systems, however poorly executed they may be. Referencing our Blog Library on this site (and on the internet in general) will evidence how much print is given to addressing hydronic distribution issues!

    The new Taco® Zone Sentry® Series Zone Valves are the “next generation” product to replace the old “Heat Motor” (energy hog) valves and be the ultimate companion to the VT2218 Delta-T ECM Circulator. They are both energy-efficient and intelligent by design as well. Whereas the old “Heat Motor” and “007” dominated and created their renowned application difficulties, the new Taco® Duo of Zone Sentry and VT2218 are their long awaited and performing successors (pictured).

    VT2218+ZV

    We among many other heating bloggers have derided simple “Zone Valves+Circulator Systems” as being an arguably cost-effective alternative to individual circulator zoned systems, and with justification. We in fact chide that zone valves+circulator systems “do nothing well”. True for the old, but not for the new generation!

    Thus, the titled “Intelligent Delta-T Circulator FHW System” consists of a Taco® VT2218 Circulator and Taco Zone Sentry® Valves coupled to a high-efficiency hydronic boiler for maximum performance. We have now and for over a generation specified and used Weil-McLain® Boilers in our applications with absolutely no regrets. Weil-McLain® is recognized as the premium All-American Manufacturer, with a growing market share. Their Warranties are fabled.

    So, to quote the old adage, “How do we get there from here?” From our perspective it’s all about education, particularly within the residential and light commercial market sector. You, the now hopefully more informed consumer, DIY (Do-It-Yourself-er), contractor, “week-end warrior”, tradesman, property manager or developer must drive this point forward in your interest.

    System specification is now relatively simple:

    1. Your total heating demand as determined by a heat loss calculation.
    2. A boiler selection by size and fuel type to suit.
    3. An intelligent Delta-T ECM Circulator(s) sized to your total heating demand.
    4. Energy-efficient Ball Zone Valves for your systems distribution controls.

    Notes:

    1. If your boiler selection has a “system loop circulator” you will employ the Delta-T System in series with it, per the manufacturer’s specification. (High-mass boilers typically don’t require a system loop.)
    2. If you wish to generate DHW (Domestic Hot Water) with your system, an Indirect Water Heater will be required. We exclusively specify and install the HTP® SuperStor Ultra, all-stainless and Lifetime Warranted.
    3. The new generation Zone Valves typically have built-in diagnostics and indicator lamp(s). Therefore you don’t need a Zone Valve Controller, as long as you can see the individual lamps. Significant redundant cost avoidance.

    Quoting Cesar Chavez 1927-1993 (American Activist and Labor Organizer): “We have seen the future, and the future is ours!”

    Mercier Engineering has seen its future as well. We have and are developing a series of “Intelligent Delta-T Circulator FHW Systems” PRODUCTS built upon Weil-McLain® Boilers, Taco® VT2218 Circulator and Taco® Zone Sentry® Valves that will provide the user with a very significant cost-performance advantage to built-on-site alternatives. They are a pre-built, assembled hydronic boiler package, ready for expedient on-site installation, with proven performance.

    Our dedicated website www.BoilersOnDemand.com is currently under complete re-construction to incorporate the latest technological innovations. It will be a significant resource to this end. Meanwhile please excuse us while we work by also taking advantage of our site’s extensive Heating Blog Library.

    Hopefully we have made you aware of hydronic FHW Heating progress and how it will definitely affect our immediate futures.

    Author’s Note: This Blog updated 08/18/2016 to reflect Taco’s new VT2218 Delta-T ECM 00e Series Circulator, replacing all prior.


  • INTEGRATING A WOOD OR COAL BOILER WITH FHW (HYDRONIC) SYSTEMS

    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


  • MULTIPLE BOILER SYSTEMS (MBS) — WHY, WHEN AND HOW

    When we think of heating systems it is logical to assume that the larger the building, the larger the boiler required to heat it. Most of us have seen the large central boiler systems employed in factories, commercial buildings or distributing heating to a campus. Some may have two boilers (or more) to assure continuity of service in an expanding campus as well.

    It is no secret that the larger a boiler, the less efficient it is both thermodynamically and particularly in seasonal operational efficiency. The efficiency spread between smaller and larger boilers has expanded in recent years to the point that our old and seemingly logical thinking has become fundamentally flawed.

    To develop this argument let us use a “two are better than one” scenario. (This can be extended to larger multiples as well, and applies to both gas and oil fired systems.)

    Firstly, all assumptions are predicated on the common denominator of structure heat loss (demand), not the size of the current boiler and its performance. Therefore the firing rate or capacity of your current boiler cannot be used for sizing comparisons. You must determine the actual heating requirement by using a “Heat Loss Calculator” of which several are available online.

    Furthermore, to arrive at a standard “Cost per Million BTU” for a particular fuel refer to our posting entitled “Using a Heat Cost Calculator — Carefully”. This will give you an accurate method of both selecting and applying values in the current environment. The heat content of fuels and their combustion efficiencies vary significantly and thus must be considered in any comparison.

    For our purpose we are assuming the published Annual Fuel Utilization Efficiencies (AFUE) of 87% and 95+% respectively of top end Weil McLain Ultra Oil and Ultra Gas products. These generally compare favorably with other competitive manufacturer product offerings and are the bases of our scenario.

    These modern, high efficiency heating appliances are limited technologically to sizing in the medium home to light commercial (and also the higher volume) market. They also vary significantly cost-wise by fuel utilized. To be more specific:

    1. The highest capacity of an 87% Ultra Oil Model nets at 172,000 BTUH

    2. The highest capacity of a 95+% Ultra Gas Model nets at 289,000 BTUH

    3. The cost of Gas vs Oil Models is significantly higher, offsetting some efficiency advantage.

    Where is the break point between a single, larger, less efficient boiler and two, smaller, more efficient ones? This is dependent upon the specifics of an application, but some general guidelines can be applied. It is generally accepted that about 70% of seasonal heating demand can be handled by one boiler of the duet. The second one is there to fulfill those peak, paralleled winter demands. A good exploratory starting point is if your heating demand is around 200,000 BTUH. Having additional demands such as Domestic Hot Water (DHW) generation, pool heating, etc. factor into the determination as well. Depending upon their quantitative and cyclical demand values they will lower the threshold between the size, number and possible dedication of boilers. Installation costs over single boilers will be somewhat higher, to be offset by efficiency gains.

    Historically the impact of Multiple Boiler Systems (MBS) can be dramatic. Common fuel usage drops of 40% are quoted in follow up reports. Their popularity in large commercial installations such as resorts, high-rise buildings and process installations are reflected in numerous trade journal articles. What is less recognized is their value in upscale housing, apartment buildings, low-occupancy, high-risk structures.

    Our personal experience with Municipal Facilities such as Libraries, Fire Stations and the like in rural areas is noteworthy. For instance, the loss potential of Rural Volunteer Fire Equipment in a freeze-up is very real, and substantial. Additionally, removal of combustion heating equipment from engine bays removes a very real high-hazard risk. The Insurance Underwriters love it!

    It must be understood that having a backup generator system is paramount to maintaining Multi-Boiler System operation.

    Beyond the efficiency claims of MBS, particularly in peaking efficiencies and managing seasonal standby losses, there are the additional benefits of alternating boiler usage (called “exercising”), automatic back-up for failures, increased boiler life and reduced maintenance. The “Boiler Manager” Control intelligence delivers idealized performance ….. always.

    For an analysis of your particular application, consult with an experienced heating engineer.

    Author’s Note: Updated 01/03/2018


  • MERCIER ENGINEERING INTRODUCES “PRE-BUILT, PRE-PACKAGED BOILER SYSTEMS”

    This Blog, originally written in 2008 has been superseded by our subsequent development activity, culminating in a Non-Provisional Intelligent Property Protection Submission (Utility Patent) in the USA & Canada in April, 2017.

    The original blog crossed out text following has been retained to witness our efforts in both timeline and content. The final submission attributes:

    1. A true hydronic appliance vs. the partially pre-built, conventional system described therein.
    2. New Delta-T ECM Hydronic Technology is fully integrated, dramatically reducing component content, increasing distribution efficiency and system performance.
    3. Gravity (Convection) Heating is optimized and provides innate, additional performance.
    4. A flexible, modular design, it is readily manufactured and provides excellent value with predictable performance.
    5. Prior and further proprietary design features have been fully integrated. Example: The “Iron Cross Manifold” has evolved into the “Compact Steel Hydronic Header” – Patent Pending.

    The ENHANCED CONVECTION, DIFFERENTIAL TEMPERATURE MANAGED, HYDRONIC HEATING APPLIANCE™ Product Brochure on our BoilersOnDemand.com website will further detail our effort. 

    Amended 07/07/2017 P.D.M., Sr.

    Modern, high efficiency hydronic (hot water) heating systems necessarily incorporate technological features that sophisticate them, particularly in the areas of controls and distribution. Whereas in the past one could make a few wiring connections and connect a few pipes, now the task may appear daunting. However, organizing these functions logically and employing selected hydronic and control components can result in both a sophisticated, yet simple system.

    Mercier Engineering is dedicated to advancing hydronic heating applications by applying the benefits of over 50 years of “being in the trenches”, so to speak. As such we recognize that there are skilled DIY’s (Do-It-Yourselfers) and Contractors who have access to skills complimenting heating installations. Our contribution is to reduce the task to a manageable one in cooperation with our customer by providing a very cost-effective, packaged forced hot water heating system.

    Since the introduction of Weil-McLain’s Ultra Series of Gas and Oil Boilers (click on our site links) and applying Taco’s renowned hydronic components and relays to them, we recognize the opportunity of readily “packaging” these products. This is further highlighted by the recent announcement of our “Iron Cross Manifold” (TM) System that efficiently configures multiple circulators and valving. Furthermore as service people ourselves this configuration is a serviceman’s pleasure, providing ready access and diagnostics for future eventualities. Note that this service is available ONLY on and limited to the Weil-McLain Ultra Series Products.

    From client supplied site detail we build the boiler systems on the Weil-McLain Pallets, then knock them down for re-shipment. All shipments are F.O.B. Antrim, New Hampshire. Note that packaging limitations may preclude commercial freight and require arranging local pickup by the client.

    To complete the installation the client will have to:

    1. Transit, de-palletize and position the system.
    2. Exhaust the boiler per manufacturer recommendations.
    3. Assemble the burner to the boiler (oil only).
    4. Extend fuel connection (gas piping or oil line) to the system.
    5. Extend 1/2″ water service to the input pressure regulator/backflow preventer.
    6. Connect the heating zone supplies and returns as applicable.
    7. Connect the thermostats to the control relay.
    8. Extend 110V 15A power service from the overhead thermal switch to the boiler service switch.
    9. Execute system fill, purge and start up procedures.

    Also note that all permits, code compliance and inspection(s) are the responsibility of the client.

    So, if you have been hesitant to upgrade and thought you just couldn’t afford a top-end Energy Star System, but have complementary skills at your disposal, this may be an answer to your dilemma.

    Contact us to discuss your particular situation. As usual there is NO OBLIGATION.