• Tag Archives Low-Mass Boiler
  • 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 desperately 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 never 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. The inherent integral instrumentation features and operational data display of delta-t circulators provide us with finite attribute identification and application control.

    The focus of our work has been to optimize the innate, but 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 “Neo-Gravity Delta-T ECM Hydronic Heating Appliance™” (Patents Pending). We claim optimization of natural gravity convection within our boiler, near-boiler distribution piping with distribution energy requirements using a single, 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 again 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” employed high-mass cast-iron boilers with larger piping to modulate heating supply, otherwise control was particularly difficult when using solid fuel firing such as with wood or coal. With generous distribution piping sizes and radiation elements gravity convection worked fairly well, and again 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 depicted in the following figures.

    The advantage is in applying natural gravity circulation to the contemporary upgrade. We have seemingly lost all 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 perimeter 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 with typical 4 GPM flow upon a 20° delta-t (adjustable) differential attainment. Compare this to 80 watts typical for each 16 gpm fixed-speed circulator or even 20 to 25 watts each for the new delta-p installs. With delta-t stabilization you can then witness circulation 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 also significantly less frequent than the system it replaces, increasing component lives.

    A personal cast-iron boiler observation: This author has never replaced a “cold shot” cracked or magnetite impaired cast-iron boiler in over sixty-five 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 the old adage? Commentary in the recent 2019 Annual Boiler Report would seem to support our contention. Read our “reading between the lines” blog on this report.

    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-five 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 prolific  system distribution piping efforts as efficiency measures they are most 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 03/03/2020 P.D.M., Sr.


  • SIMPLE, DURABLE, EFFICIENT FHW HEATING ….. PERIOD!

    Our Motto is“Simple, Durable, Efficient FHW Heating ….. Period!”. Boilers On Demand LLChas achieved this seemingly noble objective by fully integrating Advanced Taco Delta-T ECM Hydronic Distribution Technology into Forced Hot Water (FHW) Heating . The unstated result of our“Convection Enhanced Delta-T ECM Hydronic Heating Appliance” (Patents Pending – USA & Canada)development is it being highly cost-effective as well. Can we “have it all”, so to speak? Let’s look at our effort in further detail …..

    Hydronic (FHW) Heating to the layman and consumer has always had a certain mystique, evidenced by witnessing a tradesman or plumber configuring a system, piece-by-piece into a seeming maze of piping and components. The results vary from the mundane to aesthetically impressive, but we must realistically note in fact that the hydronic performance of any system is less than ideal. The residential and light commercial heating markets in particular have not had the tools nor the general expertise to optimize a hydronic heating installation. Consequently the end user has suffered with an over-installed, under-performing, energy-consumptive system over its lifetime ….. knowingly or not!

    Note: We can’t excuse our like personal participation for now sixty (60) years in hydronic heating. Our guilt is shared ….. but no longer!

    Now a true “hydronic revolution” is upon us, not yet generally known and even less appreciated, nor applied. Hydronics have thankfully been somewhat forgiving to all of us applying it, but now there’s a new day, and a new benchmark.

    By explanation, there are three (3) basic elements to hydronic heating: Energy Creation, Distribution and Radiation. Put more simply:

    1. A Hydronic Boiler to create energy by burning a fuel, as efficiently as possible.
    2. Moving (distributing) heated water to points of use with “pipes and pumps” (circulators).
    3. Warming an environment by passing air over hot piping, as simply and effectively as possible.

    We have progressed quite well in creating and utilizing energy via boilers and radiation, but that is where it has stagnated far too long. Given the limitations of fixed or selectable speed circulators and valving we have managed without addressing the true potential of improving hydronic distribution efficiency to complete the heating equation. The intelligent, variable speedDelta-T (ΔT) ECM VT2218 00e Series Circulatorby Taco Comfort Solutions® has changed it all ….. and none too soon!

    We have been experimenting with Taco® Variable Speed Delta-T VDT’s, “BumbleBees”, Viridians and now 00eSiries ECM Circulators for years, utilizing them as direct substitutes for their fixed-speed predecessors. They have worked particularly well as radiant zone circulators as our fellow tradesmen have also discovered. The Taco BumbleBee® in particular has gained trade notoriety both by its appearance and performance. However, our personal technical efforts have gone well beyond the obvious in pursuing a dedicated boiler system circulator application. It has neither been promoted nor seeming anticipated, yet its implications are very significant when achieved.

    Utilizing a Delta-T, and in particular an ECM (Electronically Commutated Motor) based circulator as a single, dedicated system hydronic “distributor” offers near-ideal efficiency potential. We slogan it as“putting an ‘Automatic Transmission’ on a boiler”. It greatly simplifies both near-boiler piping and control complexity, but must necessarily possess several operational attributes:

    1. First and foremost is reliability! A dedicated (single) system circulator failure is a potential “show-stopper” after all.
    2. Performance Flexibility. It must adapt to and accommodate all system energy demand patterns with minimal, if any effect.
    3. Accommodate an Indirect Water Heater as a prioritized and an incrementally higher energy demand accessory.
    4. Significantly improve system efficiency and performance while reducing energy requirements, both fuel and electric.

    Zone Valves are a necessary compliment to manage individual zone demands when using a single circulator. New generation valving and in particular the Taco Zone Sentry® Valve provide outstanding performance and value with self-diagnostics. The “Zone Sentry” in fact delivers three times the heating capacity of its popular “Heat Motor” predecessor, and uses dramatically less power. Combine these with its physical packaging attributes the “Zone Sentry” provides a unique configuration opportunity further addressed in this writing.

    The hydronic distribution function is composed of two elements:

    1. “Near-boiler piping” as generally referred includes circulators, valves, air elimination and expansion devices that prepare and present heated water or “hydronic energy” to points-of-use.
    2. Distribution piping that extends and presents this heated water energy to radiation components.

    We offer that considering these two distribution tasks without differentiation or distinction is fundamentally flawed, and yet is standard trade practice. As initially stated, Delta-T Distribution Technology changes this assumption, and dramatically! Consolidating hydronic flow within a single, intelligent system level circulator packaged with complimentary, intelligent zone valves packages into a true, efficient FHW Heating Appliance. Further, “hydronic convection” (gravity heating), the natural attribute of heated water to rise and convect within distribution piping is idealized as well. Witness the need to install “flow-check” valves in conventional systems piping, into circulators or using properly sited zone valves to control convection (gravity) heating. By incorporating natural convection total circulation energy is measurably reduced beyond that of Delta-T. A simple analogy would be “like paddling your canoe with the current, rather than against it”.

    Hydronic convection performance is at the core of our Proprietary Near Boiler Piping System. Included as a standard, recommended option for idealized system and DHW (domestic hot water) creation efficiency is an Indirect Water Heater(the HTP SuperStor Ultra Series). Close-coupled within our near-boiler piping, its integrated supply architecture becomes a physical, gravity flowing extension of boiler capacity, particularly in circulator fail-mode operation. Yes, we had a “fluke” 1st Generation Taco Viridian® VT2218 failure on our “Beta #3” site that was not discovered for an estimated 2-3 days of heating operation. DHW generation was never affected!

    Ideally complimenting our hydronic system is the highest-mass boiler for its rated output (the Weil-McLain UO Series), extending system energy storage capacity and potential fail-mode convection performance. Its supply and return rear porting compliment near-boiler piping by compactly and efficiently packaging all hydronics within its footprint plus an approximate 1 ft. rear piping and exhausting space. Adding the Indirect Water Heater uses under 12 sq. ft. of combined space, up to 2/3 less than a typical currently installed system while reducing system valving and near-boiler piping by up to 1/2. Integrating with domestic all-steel piping, malleable fittings and brass/bronze valving compose a free-standing system architecture of innately superb strength, chemical resistance and field proven longevity.

    Now applying our paralleled “High-Tech” Manufacturing Process expertise to Hydronic Heating, we have modularized, value engineered, methodized and tooled our Delta-T ECM Hydronic Heating Appliance to include several additional components in our Intellectual Property Protection (Patent Pending) Submission. Our cooperating customers on multiple “Beta Sites” are also providing us valuable data to optimize our system design and performance with the goal of providing an unbeatable cost-performance product.

    Taco Comfort Solutions® publishes that its Delta-T ECM VT2218 00e Series Circulator provides up to 15% fuel and 85% electrical power reductions in applications. We certainly concur! Our dedicated VT2218 system circulators are using 8-13 Watts in heating maintenance mode. Cold system warmups begin at 25-35 Watts (half the rated power) then reducing toward acclimation temperatures.

    At the extreme of our experience is our “Beta #1″ Site upgrade, badly mis-piped with three hidden, seriously undersized 1/2” radiation zone supplies & returns that exhibit high head pressures (obviously). A pre-existing integral IWH is also under-sized piped, adding to delivery issues. Yet, this system cold starts @ 65 Watts, decreases rapidly to 35 Watts, then slowly acclimates to 22-25 Watts running. (A single Taco® 007 draws up to 80 Watts by comparison. It had four operating three heating and the IWH zones.)

    Additionally by using the High-Mass Weil-McLain UO Series (Oil) Boiler(s) we see system operating temperatures lowering to 132-140º F, regulated by its integralHydrolevel “Fuel Smart” HydroStat® 3250-Plus Aquastat. System demands are readily “cushioned” by the thermal mass provided in the total system architecture. It responded very positively to the prior noted prototype system circulator failure, ramping up system temperature toward maximum with zone duty cycle duration detection & response, maintaining radiation heating in degree. Boiler burner cycles are infrequent and brief, further reducing equipment maintenance levels while extending system operating life.

    We have more recently offered the appliance-specific Carlin EZ-PRO Gas (NG&LP) vs. the Beckett NX Oil Burner in the Weil-McLain UO Boiler. Now it’s a Universal Hydronic (FHW) Heating Appliance! Change fuels ….. swap the burner only!

    Total Hydronic  (FHW) Heating System Efficiency is  the AGGREGATE  of Boiler AFUE, Delta-T ECM Hydronic Distribution & Radiation Efficiency Gains! We further claim that the reduced operating system temperatures and hence stand-by losses of the very high mass Weil-McLain UO Boiler further increase overall efficiency. Thus we can confidently claim the highest efficiency heating system available!

    System Comparison

    “Conventional” FHW Heating System         vs.         The Delta-T ECM Hydronic System

     

    Identically Specified 100KBTUH, 2-Heating Zone + IWH, Oil-Fired Systems

     

    Attribute"Conventional" System"Delta-T" SystemComments
    Boiler TypeWelded Steel Plate (Example Unit)Cast Iron "Triple-Pass"15 years +/- vs. 30 Years +
    Boiler Weight270 Lbs.625 Lbs.Very High Mass - Durability
    Oil Burner TypeVarious OfferedBeckett NX (Pressure-Fired)Flexible, stable operation
    Gas Burner TypeFixed, Appliance-SpecificCarlin EZ-PRO (NG/LP) (Pressure-Fired)Appliance-Specific Interchange
    CirculationMultiple Fixed Speed Circulators onlyA Delta-T Variable Circulator w/ Intelligent Zone Valves>/ 15% Fuel Savings
    >/ 85% Electrical Savings
    Piping/FittingsCopper (Typically)All Iron & Cast ConstructionSuperior Strength/Durability
    Indirect Water HeaterVarious Mfrs. & TypesAll Stainless Steel OnlyA Lifetime of Service
    Floor Space UtilizationInstaller-dependentOptimized Package DesignMinimum Space Requirement
    Energy PerformanceInstaller-dependentOptimized Energy DesignPeaked Hydronic Efficiency
    Component SourcesU.S./Foreign Mix (Typical)"All-American" (US/Canada)Quality and Serviceability
    Installed Cost (Oil example shown)"Over $10,000" (Oil, as shown)$7,000 (Oil, as shown)Price, Performance, Value

    To Summarize:

    Taco® Delta-T ECM Hydronic Distribution changes everything! The “Plumber’s Playground” of conventional, inefficient hydronic distribution piping “free expression” is gone as well! We must now look at Hydronic (FHW) Heating in totality, no longer as a an aggregation and assemblage of parts by personal preference. Technology has provided we heating guys with some new working tools. Let’s learn how to use and apply them well!

     Author’s Note: Updated 10/01/2018


  • THE “DELTA-T” FHW HEATING ADVANTAGE

    Whether you’re replacing an existing boiler or installing a new Forced Hot Water (FHW) Heating System, the procedure is the same. A plumbing/heating guy moves in with a service truck full of parts and tools, a supply house truck arrives and drops the boiler and sundry parts. Then the game begins …..

    The old boiler (where applicable) is removed by whatever means required, the ensuing mess is cleaned up, and the new boiler is moved into the area. Locating and positioning the boiler is the first task and directly determines the effectiveness of the entire installation. The preferences, methods, materials and the heuristic judgement of the installer prevails. Thenceforth the building of the “Erector Set” continues, pipe by pipe, wire by wire, device by device until the task is finally completed. It’s a slow, costly and inefficient process …..

    All tradesmen develop their own methodologies, reflecting their pride and workmanship in the resultant. Unfortunately the customer pays a premium for this both initially and throughout the lifetime of his system ….. knowingly or not! We cynically refer to boiler installations as “The Plumber’s Playground”, that last vestige of “free expression” removing us from the daily tedium of “fixing leaks and squeaks”.

    Installing or replacing a boiler should be no different than a dishwasher or a water softener, with a few more pipes and wires attached ….. and it can be! Problem is we plumbing/heating guys (ourselves included) continually lag technology. We “Old Dogs have to learn New Tricks”, and brother we have!

    Recent technology now allows us to configure a FHW (Hydronic) Heating System as a true appliance! All heating system functions excepting radiation can now be integrated into a “packaged unit”, engineering it for peak performance and value in the process. “Delta-T” (Differential Temperature) Circulation Technology is truly an evolutionary and revolutionary improvement. Developed in the “high-tech” process world, it has now become both practical and economical as applied to Residential Hydronics (FHW Heating).

    Mercier Engineering via its website www.BoilersOnDemand.com is the introductory leader of Residential Delta-T Hydronic Heating. The question is not if Delta-T Circulation will out-distance conventional Fixed-Speed Circulation, but when. Evidence the following Pictorials and Details for comparison.

    Identically Configured Oil-Fired FHW Installations          

    Conventional Oil-Fired FHW System   “Delta-T” Oil-Fired FHW System
    Typical Plumber Boiler Install - 18 hrs DTO-100T2(Exp)H4-4X6

    Features Comparison Table

    Attribute"Conventional" System"Delta-T" SystemComments
    Boiler TypeWelded Steel Plate (Example Unit)Cast Iron "Triple-Pass"15 years +/- vs. 30 Years +
    Boiler Weight270 Lbs.625 Lbs.Very High Mass - Durability
    Oil Burner TypeVarious OfferedBeckett NX (Pressure-Fired)Flexible, stable operation
    Gas Burner TypeFixed, Appliance-SpecificCarlin EZ-PRO (NG/LP) (Pressure-Fired)Appliance-Specific Interchange
    CirculationMultiple Fixed Speed Circulators onlyA Delta-T Variable Circulator w/ Intelligent Zone Valves>/ 15% Fuel Savings
    >/ 85% Electrical Savings
    Piping/FittingsCopper (Typically)All Iron & Cast ConstructionSuperior Strength/Durability
    Indirect Water HeaterVarious Mfrs. & TypesAll Stainless Steel OnlyA Lifetime of Service
    Floor Space UtilizationInstaller-dependentOptimized Package DesignMinimum Space Requirement
    Energy PerformanceInstaller-dependentOptimized Energy DesignPeaked Hydronic Efficiency
    Component SourcesU.S./Foreign Mix (Typical)"All-American" (US/Canada)Quality and Serviceability
    Installed Cost (Oil example shown)"Over $10,000" (Oil, as shown)$7,000 (Oil, as shown)Price, Performance, Value

    Notes:

    1. Estimated service lives are from our and our collaborating serviceman’s actual field experience.
    2. Fuel & Electrical Energy Performance per Taco, Inc. published testing data.

    Reviewing our Comparative System Photos will will confirm many of the suppositions in our “Features Comparison Table” above. The immediate impression is one of excessive plumbing and space consumption of the Conventional System. In fact the “Delta-T” System occupies 1/3 of the space, uses 1/2 of the near-boiler piping (with no copper), with only one (1) Circulator, fewer valves and fittings ….. and with optimized hydronic flow and distribution performance! Flow is so idealized in fact that under certain component fail modes “gravity induced circulation” will continue to provide heating at a reduced level! (Patent Pending)

    Arguably a high-mass (heavy) “Delta-T” System will outlast two (2) Conventional FHW Systems with a higher Hydronic Total System Efficiency at 1/3 the “life-cycle” cost.

    So when your potential FHW Heating System Installer comes calling, ask him first about “Delta-T” Circulation. If it draws a blank stare, send him home to call Taco, Inc. — and that another “Old Dog” told you to do so. After all, you the customers are deserving of all the “New Tricks”!