The measure of a heat pump’s heating performance is called coefficient of performance (COP). It’s the ratio of useful heat output divided by required energy input, where both the output and input are expressed in the same physical units.

Most of the modern hydronics technology used in North America for residential and light commercial buildings is for heating. 

The heating output and coefficient of performance (COP) of any hydronic heat pump is very dependent on the water temperature leaving the heat pump’s condenser. 

Although the market for gas-fired boilers continues to track toward those that can modulate and operate with sustained flue gas condensation, conventional boilers (e.g., those not designed to operate with sustained flue gas condensation) still represent a significant portion of the market. 

As global energy planning moves away from fossil fuels and toward electricity, an increasing number of hydronic heating systems are being supplied by heat pumps. 

Heat pumps are incredibly useful devices. 

Hydronic heating professionals often promote the concept that current generation mod/con boilers can operate with AFUEs in the range of 95% and above. 

Whenever a hydronic system is divided into several zones, it’s worth considering a buffer tank between the heat source and distribution system. 

A zone is any area of a building for which indoor air temperature is controlled by a single thermostat (or other type of temperature controller). 

Most buffer tanks used in hydronic systems are piped in a “4-pipe” configuration.