Of course, not only heat pumps, but also oil and gas heating systems cease operation in the case of a power outage. The critical moment for all units is the potential time of commissioning. In the case of monobloc heat pumps with R290, there are additional safety-related aspects to consider during downtime: In a rare but technically conceivable scenario, frost damage can cause the natural refrigerant propane to enter the heating water circuit. Automatic quick air vents and safety valves might release gas into the plant room; in the worst case, an explosive mixture could form. 

Acting pre-emptively to minimise risks

Even if power outages over several days are uncommon, both HVAC professionals and heat pump owners should be aware of this risk. The dangers to critical infrastructures such as the power supply are increasing – it is therefore advisable to recur to a proactive approach in planning and installing R290 monobloc heat pumps. For example, a temperature-dependent, frost protection valve on the outdoor unit that operates when deenergised is helpful: the AFRISO AAV frost protection valve ensures reliable and autonomous draining in the event of a malfunction, before freezing can occur.  This protects the heat exchanger and pipes.

Manual air vent and gas alarm unit for added safety

Quick air vents have the highest potential of becoming subject to gas discharged in the scenario described. Switching to manual air vents such as AFRISO PrimoVent with a collection chamber can significantly alleviate the hazard, as nothing can escape into the room in an uncontrolled manner in the event of a malfunction. Unknown to may: propane used as a refrigerant is not mixed with odorous substances and does not "smell" like gas. Monitoring in the plant or utility room provides added safety: the AFRISO GS 1.1 gas detector is installed closed to floor level to reliably detect escaping propane and alert residents in good time in the case of an emergency.

Safety valves are mandatory, but it is particularly important comply with the specifications provided by the heating system manufacturers. A recommendation from practical experience: route discharge pipes to the outside whenever possible. If, for example, a safety valve is installed in the outdoor unit, it should be clarified on a case-by-case basis whether an additionally installed safety valve is permissible at all, or whether it might be better taken out of operation.

Consultation and retrofitting by HVAC professionals

Experience from Berlin and elsewhere shows: the issue of blackouts should be an integral part of consulting and maintenance services provided by the HVAC industry – ensuring that R290 monobloc systems remain safe even when temperatures drop below zero outside and the lights go out inside.