Abstract: An indirect hot water system is provided with a secondary heat exchanger (130) that heats potable water upstream of the main heating tank (110). The secondary heat exchanger utilises refrigerant that has passed through the main heating tank. The system includes clips (40, 42, 60, 62) that support and separate the coils of the heat exchangers (108, 116) in the main tank (110) to increase the efficiency of the heat exchangers and the system overall. A pressure control valve maintains a substantially constant pressure and limits refrigerant flow in the secondary heat exchanger to maintain a high refrigerant temperature when the system is not operating at full capacity.