• Tag Archives Circulation
  • 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 Max, 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 12/23/2020 to reflect the HTP MSSU SuperStor Ultra Max, replacing all prior.


  • HIGH-MASS VS. LOW-MASS BOILERS – The Arguments

    It ultimately comes down to economics, as do most things. The current trend is to market low-mass (light-weight) boilers against traditional heavy, high-mass cast-iron boilers. However, there are non-publicized risks involved that must be assessed and quantified.

    New gas-fired appliances in particular have a technological efficiency milepost that must be considered. Specifically, the traditional tube/ribbon gas burner “dry base” boilers vs. the new condensing technology based low-mass boilers. They have a significant energy efficiency increase of 10+% in AFUE Efficiency Rating. Along with this however is a marked increase in appliance costs and operational risks — both quite important, yet never publicized!

    Stainless steel heat exchanger condensing gas units are the most popular and have been doing reasonably well service-wise. Cast aluminum heat exchanger units on the other hand where supply water pH (acidity) has not been addressed at installation or in operation have had issues, to which we can personally attest. Given this reservation they have also performed reasonably well. Being quite sophisticated control-wise, one has to admire the engineered system integrity of condensing gas systems. They certainly do flag service and maintenance issues with their sophisticated sensor complements!

    However, a disturbing pattern is emerging and the alarms are sounding in the trade journals and forums. Premature welded stainless heat exchanger leakage failures are being reported, some even “out-of-the-box” or within weeks of installation. An installed system operating life of 15 years or less is being reported in trade journal articles. The British Market Experience is much deeper and lengthier than ours and their forums are full of user complaints of premature failures and high maintenance costs. Reported system economic lives are commonly less than 10 and up to 15 years on “upscale” products. Cast-iron boilers have been effectively regulated out of the EU market. Do we have a similar lesson coming?

    The common cause of failure for all condensing boilers should be water condition issues, but it’s also become manufacturing process integrity in some cases. Regardless, manufacturers are countering with stringent water condition qualification requirements within their typically 10-Year Pro-Rated Warranties. Not only do water conditions have to be measured and recorded at installation, but subsequent annual service procedures must re-qualify and record these values. Violate your water control guidelines and void your warranties!

    Oil-fired appliances on the other hand are a different animal, with combustion energy containment and management paramount in their design. Heating oil has over 60% more energy content per gallon than gases and can’t be technologically “modulated” (vary the firing rate) as with a gas appliance. Adjusting the output of an oil boiler is done by managing system temperature and/or by utilizing multiple boilers (MBS Systems) in larger installations. Therefore the oil boiler must be designed to perform at its maximum firing rate and within its design parameters. This is typically accomplished by using a cast-iron heat exchanger, and has been the norm for the past two hundred years!

    Let us first disqualify any “dry base” welded-steel-fabrication (oil or gas) boilers from this discussion. Their poorer field performance history in both thermal efficiency and longevity are well documented and recognized. They are sold on price alone. If you have one, you won’t have it for long — unless you were born under a lucky star! (They now barely meet D.O.E. Energy Star Ratings as well, and we hope for not much longer.) Particularly disturbing to us is the poor field history of a nameless, highly publicized “high efficiency” gas-or-oil welded plate construction boiler. Their factory service record as emoted both directly by us, our trade service collaborators and their customers is damnable! Independent servicemen hate to touch them. Parts are product-specific, pricey and their eventual structural fate is predictable. We regard them as a “black eye” upon our industry. Beware of the sales pitch and do your homework! Always get customer referrals at a minimum (including for ourselves)!

    The “wet base” full-combustion-containment cast-iron oil boiler is the industry standard, with a solid performance history. They do however differ by both manufacturer and specific model design attributes that may affect life performance. If your oil boiler does not last at a very minimum 30 years or more, something is very wrong. We have replaced 100+ year old cast iron boilers with still beautiful castings, but you just couldn’t afford to feed them! You are more likely to see a cast-iron boiler section seal corrosion failure in particularly older units or hard-freeze icing fracture neglect than a “worn-out” boiler. Either situation is economically catastrophic though, requiring unit replacement.

    The high-mass vs. low-mass oil boiler argument ultimately comes down to design parameters, material selection, application integrity and its performance under field conditions. The design safety factor of any cast iron boiler can be readily extended by simply providing more iron and more water capacity. “The more it weighs, the longer it stays” – our poor poetry. Works every time, but potentially adds cost to the boiler — as it should.

    We must now extend the preceding arguments to contemporary oil & gas appliance issues. There are three emerging problems well documented in Heating Trade Publications that must be addressed:

    1. “COLD-SHOTTING”. A trade term that describes the condition where cold water is introduced into a hot boiler and thermally “shocks” the heat exchanger metallurgy. Single or cumulative events can result in catastrophic metal fracturing, seal and/or weld joinery failures. The “solution” is the additional piping and installation of a Boiler Return Water Temperature Control Valve to any condensing or low-mass boiler system. This is not an issue with a high-mass cast-iron boiler, nor has it ever been. Please note that Delta-T ECM Hydronic Distribution Technology properly applied will also negate this issue altogether.
    2. MAGNETITE ALLEVIATION. Magnetite is a magnetic, accumulating ferrous (iron) oxide (rust) present in boiler and supply water and attaches itself to internal boiler components, reducing in particular circulation efficiency. It has virtually never been an issue in a cast-iron (a naturally magnetite scavenging material) boiler, but here it is with very low iron content condensing systems. It can only be addressed with an integral, full-time Magnetite Filtration System – a significant initial cost and recurring maintenance additive.
    3. HYDRONIC DISTRIBUTION. Contemporary practices of near-boiler and distribution (to radiation) piping are excessive, unwarranted and inefficient. (We refer to this as “The Plumber’s Playground”.) The seemingly excessive piping and controls witnessed in new installations are so, REDUCING system efficiency while increasing distribution power demands. Low-mass and condensing boiler systems are disproportionately affected. Again, correct application of Delta-T ECM Hydronic Distribution Technology is a must for overall system performance.

    If you’ve read from our “Heating Blog Library” on this site, you would certainly qualify us as “High-Mass Boiler” advocates. We have additionally optimized our system design and performance by fully incorporating “Delta-T ECM Hydronic Distribution Technology”. It smooths hydronic system thermal demands while significantly reducing operating costs. We slogan this as: “Putting an ‘Automatic Transmission’ on a Boiler”™ — to use an automotive analogy. In fairness this technology would certainly be very beneficial when applied to any low-mass boiler! In fact we consider it a prerequisite in any low-mass boiler installation. Please reference our new Packaged ΔT ECM Hydronic (FHW) Heating Appliance™ (Patents Pending – USA & Canada) on this site, interchangeably fired by OIL or GAS.

    Considering the aforementioned, we much prefer high-mass boilers with their “thermal damping” and reduced cycling characteristics. More iron mass and greater water content equals less burner cycling and ultimately longer component life. We have noted in fact (although we don’t necessarily advocate it) that ultimately a boiler maintenance cycle is now more dictated by the quality and amount of fuel oil passed through our Weil-McLain Ultra Series Triple-Pass Boilers than calendar cycles. Their heat exchanger passages are very open compared to prior generation two-pass units. Combined with the combustion quality of the Beckett NX Burner you generate very little ash accumulation. The same cannot be said of a nameless foreign boiler that seems to have high ash generation and more frequent maintenance calls. (We refuse to service them, by the way — hire the mechanic with that “Mercedes”.)

    TRY THIS: Divide the Cost of a Boiler by its Shipping Weight to determine its approximate the Cost per Pound. The Weil-McLain UO is 1/2 to 2/3rds the Cost-Per-Pound of ANY equivalent U.S. or Foreign Boiler! Just what are you buying – durability or ….. ???

    Summarizing, weigh the operating characteristics of your particular hydronic system application before you select any boiler. In particular look at an intelligent hydronic distribution option such as the Taco® Delta-T ECM Distribution System. Just “plugging and playing” a low-mass boiler into your system may not play too long, nor too well.

    Additionally, a very timely read is our commentary on the just published 2019 Annual Boiler Report. “Reading between the lines” we extract the admonition by several manufacturers that despite their pursuit of highly engineered condensing product offerings, a well configured cast-iron boiler system is still economically favorable. It appears, as we advocate, that a proven high-mass, triple-pass cast-iron boiler system fully integrating Delta-T ECM Distribution Technology prevails. The resultant is “SIMPLE, DURABLE, EFFICIENT HYDRONIC (FHW) HEATING ….. PERIOD!  Judge for yourself …..

    (Please refer to our other blogs and appropriate external sources for detail related to this discussion.)

    Updated: 04/03/2020 PDM, Sr.