• Tag Archives Zone Sentry
  • DELTA-T ECM HYDRONICS – Redefining “The Plumber’s Playground”

    Hydronic heating comprises warming water as a medium, moving and expending its energy to warm an environment. Thus we have boilers as heat generators and radiation to convert heated water into warmth. Between these we must distribute our medium via pipes, pumps, valves and controls to meet heating demands.

    Basic hydronic system design rules of course must apply, but by and large the final product interpretation has been left to the tradesman/installer. This individualization provides a very attractive latitude of self-expression. Like an artist painting on a new canvas individual skills, styling and practice all comprise the final “picture”, with the author’s “signature” applied. Based upon our field observations we have come to refer to hydronic distribution in particular as “The Plumber’s Playground”, and with no apologies offered.

    Unfortunately the Laws of Physics apply equally to hydronic system installations as to any other enterprise. Therefore that maze of pipes, valves, circulators, controls and wiring evidenced in a “plumbers playground”, no matter how pretty, daunting or impressive is unnecessarily complex, costly and under-performs. In fact any system installed within the past three years or more not employing Delta-T ECM Hydronic Distribution Technology specifically is woefully under-performing!

    The Heating Game has changed, led by the Taco® Delta-T ECM VT2218 Hydronic Circulator and its supporting Taco® Zone Sentry Valves. We refer to it as “The Hydronic Revolution”, as it truly is! These two (2) devices, properly applied, can and do dramatically simplify the complexity and content of a conventional hydronic heating system. Again, properly applied and supported by contemporary control systems provided by an “Intelligent” System Aquastat with idealized piping (plumbing) can further enhance performance, as our work has evidenced. Our development efforts and observations are reflected within the remainder of this presentation.

    The Delta-T ECM Variable Speed, Intelligent, Multi-Temperature-Sensing Circulator is a marvel of applied technology. Its ability to sense, measure and maintain a preset temperature differential in a hydronic circuit virtually optimizes heat transfer efficiency in a single, automatic step. Further being able to accommodate varying demands from multiple zones (circuits) virtually seamlessly as we have evidenced places it as the heart of any hydronic system. Using an automotive analogy we slogan that we are putting an ‘Automatic Transmission’ on a Boiler, but doing it hydronically.

    Now pair this Taco® Delta-T ECM Circulator with a compliment of their Zone Sentry® Zone Valves and you dramatically reduce energy consumption while gaining some further fuel efficiency. As Taco® promotes we are seeing distribution power consumption drops to 11-13 watts and in another instance to 8 watts during normal operation! Compare these with 80 watts for a single Taco® 007 and 21 watts each  for a Heat Motor Zone Valve. (The Zone Sentry® uses 11 watts, and then only in a brief actuator “charging cycle”.) Hydronic heating system power consumption is virtually never considered in design, but it should and furthermore must be!

    Piping is the pride of any plumber (ourselves included) yet in so being can become a detriment to system performance. To this point we offer that hydronic convection (the natural attribute of heated water to rise, and cooler fall) is not considered as a positive contribution to system performance, but an attribute to be controlled. As we have witnessed in our design effort however, natural convection is a measurable asset, particularly when configuring piping and placement to maximize its effect. Near-boiler piping, to employ the trade term, is crucial to maximizing hydronic performance. Compacted packaging of correct pipe sizing and layout close to the boiler displays great natural (non-powered) circulation that may not only supplement but also heat at reduced levels. We had an early Delta-T Circulator failure on one of our “beta” installations that was not discovered for an estimated 2-3 days! How’s that for convection — like “paddling your canoe with the current”.

    When you fully integrate the “intelligent” Delta-T ECM Circulator, Zone Valves and Aquastat with idealized convection you come to the conclusion that hydronic system installation is no longer a process, but functionally becomes an Appliance. Our resultant “package” is contained within its boiler footprint plus minimal rear piping space. A designer need only define system capacity, number of zones, fuel type and exhausting to define the “appliance”. Further, the application lends itself to modularization, and thus to versatility by default. Not only do we significantly reduce the material content of a system, but its labor content and installation time as well.

    Now there is both a trade and consumer option, a virtual Hydronic Heating Appliance with a fixed cost and defined, superlative performance. Our work to date has been developing a “Package Delta-T ECM Hydronic (Oil) Heating System” that achieves its higher performance by incorporating Delta-T ECM Hydronic Distribution Technology with a high-mass, lower operating temperature boiler for optimized performance. But also recognize that Delta-T ECM Circulation will work on any fueled hydronic application, putting an “automatic transmission” on ANY boiler. This obviously reduces the size, content and complexity of the “Plumber’s Playground”, but to a net performance advantage in doing so.

    To summarize, a “Hydronic Heating Appliance” is in our near future, defined by technology and necessitated by the market, like it or not. Its Performance Specification will virtually determine system performance, unlike the potpourri of present practice. Our publicized contributions are documented on our website www.BoilersOnDemand.com.  Please note that our current and following product offerings are under Intelligent Property Protection (Patent Pending). We look forward to “Boilers On Demand” in the new “Plumber’s Playground”.


    There is a conflict (war) between the new energy-efficient zone valves and their thermostat counterparts. It is little understood and lesser recognized. The effect is erratic or non-operation of heating zones, frustrating both heating system owners and their servicemen.

    While discussing zone valve application specific to our “Package Delta-T ECM Hydronic (FHW) Heating System™” (Patents Pending – USA & Canada), Taco Engineering offered that there are disparages emerging between some “new generation” thermostats and proper zone valve operation. We were discussing specifically the Taco “Zone Sentry” Valve, a low power usage zone valve featuring extreme energy efficiency and operating life. This conflict is strictly a thermostat product design issue, evolving from the effort to incorporate more and more features into thermostats.

    The primary function of a thermostat is a “temperature sensing switch” presenting power (24VAC) provided by a transformer to operate a zone valve (or a circulator). The thermostat must also use a small amount of power to warm an “anticipating heater” that “tricks” its switch into closing earlier to smooth heating delivery by utilizing the heat stored in piping and radiation to “fill in” between thermostat cycles. A pure “temperature switch” has a high “hysteresis” or sensing lag and would have noticeable hot and cool periods in operation. A major advantage of the new Taco Zone Sentry Valve is now powering up to 12 valves from a standard 24VAC transformer vs. 4 of the prior generation “Power Head” or “Hot Head” valves as we cynically refer to them. The resulting electrical power savings benefits are dramatic (up to 85%)!

    Beyond the primary function of heating control modern thermostats incorporate more features that require using more power to execute them. Being effectively non-powered devices as designed they “borrow” their power from the zone-valve source 24VAC supply. This has generally worked with common “set & forget” and basic programmable thermostats with a battery backup. However adding features such as Wi-Fi and wireless inter-system controls require more and continuous power demands to maintain these communications features. Taco Engineering is experiencing ever more issues with these thermostats directly operating their zone valves and uses the term “Power Grabbers” in classifying them.

    Drawing down the 24VAC supply power will ultimately cause erratic Zone Sentry Valve behavior. This is typified by:

    1. Multiple “open” attempts, witnessed by viewing the Green LED Status Lamp, before finally opening.
    2. Occasionally the valve will not “close” after the zone thermostat demand is satisfied.
    3. The worst condition is the zone valve simply failing to operate upon a demand.

    Taco offers the following observations and possible solution:

    1. First, check your thermostat for correct mode switch settings for your system type, per the manufacturer’s instruction sheet. These are typically on the back of the thermostat, and match operation to your system type.
    2. If your thermostat manufacturer provided a resistor with the unit, install it per the instructions and retry operation.
    3. Taco otherwise recommends installing a 1.0-1.2 kohm, 2 watt or greater resistor in series with the power (red) lead. This will usually remedy the situation.
    4. If not, consult with your thermostat manufacturer to remedy, if possible.

    The more we demand of particularly digital temperature devices, the more potential control issues we incur. A sample of our observations:

    1. The Honeywell T86/T87 Series Thermostats (those old round ones you adjusted by turning the outer ring) were extremely durable, dependable and finitely adjustable, being “analog” devices. Their “anticipating heater” (as previously described) was infinitely adjustable and you could “tune” it to less than 1/2 Deg F. Resistor “tuning” range was from 0.2Amp to 0.6Amp, infinitely variable. They were banned due to containing a drop of mercury as the switching medium. (We advise our clients not to “upgrade” them unless they need a programming capability.)
    2. Digital Thermostats have selector switches prescribing a fixed “anticipating heater” value for each general system type and are non-adjustable. Thus you will have minor(?) control variations from the “correct” one.
    3. Zone Valves in particular require a higher “anticipating heater” setting than circulatory-driven systems, typically 0.5A (Zone Sentry) to 0.6 (Older Zone Valves) vs 0.35A+/- for aquastat/relay drives. This fine tuning is not available in a digital thermostat, thus minor(?) operational variations.
    4. Tuning a steam system upgrade to its robust radiation (cast-iron radiators) with a digital default thermostat can become a challenge.

    In closing we mention several of our customers being true “techies”, two of whom having commercial and home-built Wi-Fi Thermostat or Temperature Monitoring Systems. One recently called from a Hawaiian Job Site advising of an issue in his seasonal home in NH. Saved a potentially disastrous situation. Welcome to the “Digital Age”, but also be aware of its limitations!




    A Forced Hot Water (FHW) Heating System is designed to efficiently provide energy distribution to heated areas. This is accomplished by combusting fuel in a boiler and moving the heated water through radiation to warm the desired environment.

    However, to accomplish this most efficiently requires:

    1. A high-efficiency appropriately sized and fired boiler.
    2. Properly proportioned and positioned radiation for each heated area.
    3. Idealized, simultaneous energy delivery of heated water to all radiation, irrespective of heating demand patterns.

    Practically however, none of these elements are absolutely correct, nor can they be. Boilers and radiation are almost never idealized for efficiency, but the third (energy distribution) is typically the most poorly executed of all. You must deliver heated water at an ideal rate for maximum heating transfer efficiency.

    Common distribution systems typically consist of:

    1. Dedicated circulators for each zone, or
    2. A common circulator with a zone valve for each zone.

    These configurations do not perform efficiently in practice, and in particular zone valves.

    “Delta-T” is a technical connotation. “Delta” (from the Greek letter ∆) is difference, or differential. “T” designates temperature. Thus Delta-T (∆T) is “differential temperature”.

    The Delta-T Continuously Variable Speed Circulator  employs temperature sensors attached to the boiler supply and returns points. It measures and maintains the ideal temperature differential by infinitely adjusting its water delivery rate (pump speed) to suit. Coupling with the new Low Energy, High Flow Zone Valves this technology maximizes the efficiency of any hydronic system with dramatically reduced electrical power consumption.


    Additionally, this system also smooths the performance of your existing radiation by typically eliminating hydronic whistle from over-sped, heating lag and imbalance from under-sped zones.

    No costly control system is necessary! The innate intelligence of the Delta-T Circulator teamed with the self-diagnostic capability of this new generation “Green” Zone Valve simplifies wiring, installation and diagnosis.

    It’s a Terrible System. Terribly Simple – Terribly Efficient!