When a fixed output heat pump supplies a highly zoned heating or cooling distribution system, a buffer tank is typically used to prevent the heat pump from short-cycling under very low load conditions.   

More and more hydronic heating and cooling systems are being designed around air-to-water and water-to-water (geothermal) heat pumps. When the heating distribution system is extensively zoned, a buffer tank is typically installed between the heat pump and that distribution system.

One of the best things about hydronic heating systems is that it’s easy to integrate some method of domestic water heating. This combination has been used for decades in systems where a boiler was the sole heat source. It’s also possible when a heat pump serves as the heat source.

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. Some use water-to-water heat pumps supplied by geothermal earth loops. Others use air-to-water heat pumps.

An installer recently read about the benefits of piping a buffer tank in a “2-pipe” configuration.  

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

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

Through and around.