Residential

GeoPro Design was contacted by a client after a competitor installed a system that failed to function correctly.

The heat pump supplies the hot water for the distribution system, which in this case is a multi -zoned radiant floor heating. It appears that the installation does not have a thermo store or buffer tank and the installation.

Because of this, the heat pump will respond just like a fixed capacity boiler. Whenever there is a call for heat from a zone, it will turn on. In many cases it will generate heat at a rate far greater than the rate of heat dissipation by the active zone(s). Since there is very little thermal mass in the system, it will short cycle. This is especially hard on the compressor. The starting amperage of a compressor this large will also tend to momentarily dim the lightsThe system needs thermal mass in the form of a well-insulated buffer tank. It also should have an expansion tank and air eliminator on the earth loop.

Because of the extensive zoning using valve actuators the distribution system should have a differential pressure bypass valve, or even better, a variable speed pressure regulated circulator. The temperature in the buffer tank can be regulated with outdoor reset control in response to outdoor temperature. This allows the heat pump to operate with the lowest possible supply water temperature and thus the highest possible efficiency. Installing a buffer tank will also avoid cycling and reduce the operational time of the GSHP.

Take a look at the before and after images.