I recently designed a system for my daughter’s new home with a water-to-water geothermal heat pump as its main heat source. The intent was to provide space heating and domestic hot water with heat from the heat pump.
The space heating distribution system, which was described in the January 2020 Hydronics Workshop column, was extensively zoned. There are seven individual zones with a combined design load of only 29,700 Btu/h. Some of these zones are single panel radiators with design outputs in the range of 1,400 Btu/h. To avoid short cycling the heat pump, we planned the system around a 119-gallon buffer tank. A portion of the system’s piping is shown in Figure 1.