I recently reviewed a project in which a municipal building was being connected to a district heating system supplied by pellet-fueled boilers.

The Coefficient of Performance (COP) of a heat pump is essentially the same concept as the thermal efficiency of a boiler (e.g., the desirable output divided by the necessary input).

With systems dating back into the 1800s, hydronic heating has been around a long time. As with many technologies, a modern hydronic heating system bears little resemblance to one based on the earliest design techniques and hardware.

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.