Do I Need a Hot Water Cylinder With a Heat Pump?

Yes, in most cases you will need a hot water cylinder if you want an air source heat pump to provide domestic hot water (DHW). Unlike a combi boiler, most heat pumps do not heat water instantaneously as it passes through the appliance. Instead, they heat water gradually and store it in an insulated cylinder, ready for showers, baths and hot water taps.

What Type of Cylinder Does a Heat Pump Need?

An external air source heat pump normally requires a heat pump compatible hot water cylinder with a suitably sized heat exchanger coil.

Heat pumps generally operate at lower primary flow temperatures than traditional gas or oil boilers. A larger surface area coil allows sufficient heat to transfer into the stored domestic hot water while maintaining efficient operation.

Using an existing cylinder with an undersized coil can result in longer recovery times and reduced efficiency.

Do Integrated Heat Pump Water Heaters Need a Separate Cylinder?

No. An integrated heat pump water heater combines the heat pump components and insulated hot water storage cylinder into one appliance.

These all-in-one systems are designed specifically for domestic hot water production and do not require an additional external cylinder.

Why Is Cylinder Size Important?

The correct cylinder capacity depends on household occupancy, shower and bath usage, peak hot water demand and heat pump recovery time.

A correctly sized, well-insulated cylinder provides sufficient stored hot water while helping the heat pump operate efficiently.

In summary, an external heat pump generally requires a separate hot water cylinder, while an integrated heat pump water heater already includes one.