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The more you understand the difference between Delta-T and Delta-P, the better you can serve your customers with the energy-saving components and systems that are right for their home - and their energy budget!
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System Design with Differential Temperature (Delta-T)

North American residential system design is pegged to the temperature differential between the supply and return (Delta-T). It's part of the Universal Hydronics Formula, it's how we size boilers, select pipe size and determine the amount of radiation to put into a room. We also zone our systems and turn them on and off via a thermostat on the wall- all in an effort to deliver comfort.

Smart Delta-T Circulators

If we use a Delta-T based smart circulator in these North American systems, like the Taco Bumble Bee or 00-VDT, it reacts to how many zones are open, which zones are open, and even how cold it is outside, automatically - without an outdoor sensor. These infinitely variable speed Delta-T circulators deliver ONLY the BTU's required to match the actual heating load required by each zone. The entire system runs at peak efficiency, no matter the time of year, accurately providing optimum comfort and real electric and fuel dollar savings.


Delta-P Circulators

On the other hand, Delta-P ECM circulators operate best on constant circulation and utilize thermostatic radiator valves (TRV's), instead of thermostats, to control the flow to panel radiators. As the TRV's modulate open and closed, the pressure in the system changes and the Delta-P circulator speeds up and slows down to compensate for the change in pressure.

In North American systems with on-off zone valves, those pumps read the number of zones in the system, assign a fixed speed for each open zone and switch motor speeds depending on which zones are open. It's like having a "however many zones are open speed pump." It's important to know that if you prefer to zone with circulators, Delta-P pumps never vary their speed - they work just like a single speed pump.

Which to choose?

If comfort delivery and efficiency are your goals than choosing the right circulator based on the system design can make all the difference. Delta-P circulators only adjust to changes in system pressure. Delta-T circulators measure the temperature difference between supply and return and infinitely vary their speed to deliver spot-on efficiency, compatibility, and comfort. Then add Zone Sentry Zone Valves and Taco Controls for the most efficient comfort system available anywhere.

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Proof of Delta-T's Superior Efficiency
This graphic
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