The answer

Why might a heat-pump installation need a different cylinder?

Possibly. A heat pump often needs a cylinder that can heat water effectively at a lower temperature. The right size depends on your baths, showers, available space and how quickly the tank needs to heat again.

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Replacing a combi boiler may need space for a tank

If you have no hot-water cylinder now, the installer must find a suitable place for one and plan the pipes and controls. Check access before treating it as a small extra item.

02 / 03

Tank size is not the whole answer

How much usable hot water you get also depends on temperature and how quickly the tank heats again. Tell the installer about baths, showers and times several people need hot water close together.

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Ask when the water will be heated

The schedule, any electric immersion heater and the hygiene cycle affect both cost and availability. Ask your installer to explain the settings you will live with day to day.

How much hot water does your household need?

A combi boiler heats water as it is drawn; a heat pump commonly needs stored hot water. A household's shower pattern, baths and simultaneous use affect volume and recovery time. An existing cylinder may have inadequate coil area to transfer heat at the planned temperature, even if it has enough litres on the label.

Ask where a replacement cylinder would fit and how it would be moved into the property. The proposal should explain heating priority, the normal storage temperature and the hygiene cycle, including any immersion use. A cylinder decision made late can change both cost and room layout.

What to check next

Your next steps

Describe when your household uses the most hot water
Ask whether the existing cylinder can heat and store enough water
Check that a replacement cylinder would fit and can be installed
Ask when the immersion heater and hot-water hygiene cycle would run

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?