This is the last of three columns describing a combisystem that uses an air-to-water heat pump and a mod/con boiler to supply heating, cooling and domestic hot water. We discussed the concept in the October Hydronics Workshop column (“Dynamic duo”) and the piping in the November column (“Piping a dual-heat system”). This month we’ll look at the control system, and make sure the system is fully documented.
Figure 1 shows the piping schematic as we left it last month.