The answer

What flow temperature should a heat pump use?

The best setting is low enough to run efficiently but high enough to warm every room on a cold day. Your installer should calculate this for your property and radiators rather than promise one temperature for every home.

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Lower water temperatures can cost less to run

A heat pump usually works more efficiently when it does not have to make the water as hot. Better insulation or larger radiators may help, but only if they let the whole home stay warm at that lower setting.

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One cold room can set the temperature for the whole system

If one radiator is too small, the installer may have to run the water hotter for every room. A room-by-room check shows where changing one radiator could make the whole system work better.

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The controls should respond to the weather

Many heat pumps adjust water temperature as it gets colder outside. Ask your installer to set this up, show you how it works and explain when you might need to change it.

Will your radiators heat each room at that temperature?

A heat pump usually works best when the water it sends to your radiators is not hotter than necessary. But every room still has to get warm enough. If one radiator is too small, changing that radiator or improving insulation in that room may make more sense than turning up the temperature for the whole house.

Ask how the system will adjust its water temperature as the weather changes. Your installer should set it up after fitting it, show you how the controls work and explain whether the running-cost estimate assumes those settings.

What to check next

Your next steps

Ask what water temperature the heating system will use on a cold day
Check the radiator or underfloor-heating plan for every room
Ask how the controls will adjust the temperature as the weather changes
Check that the running-cost estimate uses those same design settings

Where we checked the facts

Check the original information.

These official pages back up the rules and technical details above. They can change, so check them again before spending money or starting work.

Apply this to your own property

Could a heat pump work at your property?

Every property is different. A free survey checks heat loss, hot water and radiators to see whether a heat pump may fit before a system is priced.

Request a free heat-pump surveyJust have a question?