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Focus on high temperature heat pumps


Jo Alsop

Heating Hero

The Heating Hub

Jo explores why high temperature heat pumps might have an important role to play in decarbonising some properties.


Is a high temperature heat pump the right renewable for you?

In what will undoubtedly be a mix of renewable options for homeowners, heat pumps have been identified as having a major part to play in decarbonising our homes. Low temperature heat pumps can comfortably heat our homes, however they will require us to fit larger radiators and heavily insulate our properties.

The Committee for Climate Change has identified high temperature (HT) heat pumps as a viable option for many households where low temperature heat pumps are not practical. HT heat pumps can run our existing radiators with little or no adjustment, however they are less efficient and more expensive to fit. We explore the pros and cons of this renewable technology.

Our existing housing stock

The vast majority of UK homes are set up to run with a gas or oil boiler and high temperature radiators. For the old-style non-condensing boilers, temperatures from the boiler to the radiators are 80 degrees.

For modern condensing boilers, heating temperatures should be lower in order for the boiler to run at its higher efficiency, although this rarely happens in practice. But certainly 65 degree temperatures from the boiler can operate a standard radiator based heating system.

Barriers to low temperature heat pumps

All air source heat pumps are viable alternatives to our gas and oil boilers. With capacities between 3-16kW as standard, they have the potential to heat most UK homes; the average heat requirement being just 6-8kW on a very cold day.

However low temperature heat pumps are at their most efficient when the heating system temperatures run at 35-45 degrees. Our homes can still be heated using this lower temperature, but our radiators will need to be much bigger in order to give off more heat. A new low temperature heat pump will therefore also mean new radiators throughout, unless we have drastically improved our insulation levels.

High temperature heat pumps

HT heat pumps have been designed to operate at 80 degrees and so can heat standard radiators. Other advanced heat pumps operate up to 65 degrees and are also good candidates for existing heating systems. (See table below.)

The disadvantages are that high temperature heat pumps are more expensive to fit and less efficient than low temperature models. The external units are also much larger so a garden is necessary. Never-the-less they may be the only option for some homes.

High temperature heat pump options

Manufacturer Name Operating temperature Size kW SCOP
Daikin Altherma 3 65 degrees C 4-6kW 3.26 @55 degrees C
Daikin Altherma HT split 80 degrees C 11kW 2.65 @ 55 degrees C
Daikin Altherma HT split 80 degrees C 14kW 2.66 @ 55 degrees C
Daikin Altherma HT split 80 degrees C 16kW 2.61 @ 55 degrees C
Hitachi Yutaki-S80 HT 80 degrees C 11kW 3.63 @ 55 degrees C
Hitachi Yutaki-S80 HT 80 degrees C 14kW 3.31 @ 55 degrees C
Hitachi Yutaki S80 HT 80 degrees C 16kW 3.23 @ 55 degrees C
LG Therma V New HT split 80 degrees C 16kW 3.21 @50 degrees C
Panasonic Aquarea HT Monobloc/split G Gen 65 degrees C 9kW 2.27 @ 65 degrees C
Panasonic Aquarea HT Monobloc/split G-Gen 65 degrees C 12kW 2.22 @ 65 degrees C

When is a high temperature heat pump right for me?

Without doubt the next decade will be a drive towards insulating our homes so that we can fit low carbon technologies and low temperature heat pumps in particular.

There will be some properties for which significant levels of insulation is not possible however, for example listed and older properties. Where there seems little prospect of your heating system ever running at 45 degrees, then a high temperature heat pump is a great option that can be fitted now and you can partially decarbonise your home immediately.

HT efficiencies

With the correct set up homeowners can expect SCOP of around 2-2.5. This is means for every one unit of electricity the unit will generate 2-2.5 units of free energy from the air.

The SCOP is the efficiency of the heat pump over the year. Efficiency will be significantly lower in winter when the heat pump will be running at its higher temperatures and more efficient during spring and autumn months when it can run at lower temperatures.

Whilst high temperature heat pumps are capable of heating of 65 or 80 degree temperatures, that is not say they should run at this temperature. The higher the temperature the lower the efficiency. The heating system should be designed so far as practical to run as low as possible and only rely on the top temperatures when absolutely necessary.

How do I find an installer?

There are lots of heat pump installers across the UK. In all cases they must be MCS registered. The standard of installation is patchy as we are still getting to grips with the technology and demand is rising. We have some of the best heating engineers in the UK on our Elite Installer network. You can contact us if you would like to explore a heat pump for your home.


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