Housing unit for a heating system

A heating device with two heating circuits, one for space heating and another for service water heating, a valve (14) for switching between the heating circuits, a recirculation pump, a plate heat exchanger (6) for service water heating, a heat exchanger (5) for space heating and a housing unit (22), said housing unit (22) comprising:

• a pump housing (23) for the recirculation pump (8);
• an inlet chamber (28) of the pump housing (23) adjoined by an inlet mouth (26) of the recirculation pump (8), the valve (14) being located within the inlet chamber (28);
• the inlet chamber (28) having an opening (29) in one side thereof, receiving a first return line (12) from the heat exchanger (5) for space heating, and a pipe (39) projecting into an opposing side of the inlet chamber (28) and receiving a second return line (13) from the plate heat exchanger (6) for service water heating;
• and
• a bypass (17) of the valve (14) branching from the second return line (13) to a second opening (53) of the inlet chamber (28), the bypass (17) being closed by a pressure relief valve (18) adjacent the second opening (53), wherein the bypass (17) empties into the inlet chamber (28) via the pressure relief valve (18) when the pressure relief valve (18) is opened.