My heat pump is rated down to -25°C, do I have to turn it off when it reaches a lower temperature?

If your heat pump system is rated to operate at temperatures as low as -25°C, it means the system is designed to maintain efficient heating performance down to that temperature. However, it does not necessarily stop working when the temperature drops below -25°C. Here’s what happens: 

1. Performance Decline: 

• Below the rated temperature, the heat pump’s ability to extract heat from the outdoor air diminishes, so its heating capacity decreases significantly. 

2. Backup Heating: 

• Many heat pumps include an auxiliary or backup heating system, such as electric resistance heaters or a gas furnace, to provide additional heat if the outdoor temperature drops too low for the heat pump to meet demand. 

3. Shutdown Possibility: 

• If the temperature falls far below the system’s design limit and no backup system is available, the heat pump may shut down to protect its components from damage. 

4. Cold-Climate Heat Pumps: 

• Some modern cold-climate heat pumps are capable of continuing to operate even below their rated temperatures, though with reduced efficiency. 

Key Takeaway 

A heat pump rated to -25°C is optimized to deliver reliable heating at that temperature, but extreme conditions below that may require supplemental heat. If you’re in a region with temperatures regularly dropping below this limit, ensure your system includes an adequate backup heat source.