A guide to high temperature heat pumps

• High temperature heat pumps can rival gas boilers’ efficiency. 
• While relatively new on the market, they are quickly being adopted as energy-efficient home heating solutions. 
• This is bolstered by the fact they don’t require new insulation or radiators, unlike regular heat pumps
• They are currently more expensive than conventional boilers or heat pumps. However, they pay for themselves quickly, given the energy savings they make. 

High temperature heat pumps are an excellent solution for many properties. And with heat pump costs coming down rapidly, you can affordably replace your gas boiler while helping the climate.

In fact, according to some estimates, heat pumps should cost around the same as a gas boiler by around 2030. Some even believe costs could be reduced by as much as 50% by 2025.

These machines can also be installed without extra hassle. Moreover, they can heat your home at the same speed as a gas boiler, making them a sensible choice.

In this guide, we’ll explain how they work and why you should – or shouldn’t – look into purchasing one for your home.

If you want to see if a heat pump would be right for you, pop your details in this quote tool to receive free quotes from our expert installers.

What is a high temperature heat pump?

A high temperature heat pump is a renewable energy system that can heat your home to the same level of warmth but considerably faster than a regular gas boiler.

• These heat pumps can reach between 60°C  and 80°C , normal heat pumps only reach 45°C  to 55°C

• It achieves this using superior refrigerants and compressor technology, making it more efficient than standard heat pumps. Two-stage compression is also possible in some models, significantly improving their efficiency.

• Most high temperature pumps use R290 or R32 refrigerants, which are better for your home and the climate and come with industry-leading weather compensation controls.

• According to a recent government report, high-temperature heat pumps must raise their flow temperature above 65°C less than 1% of the time.

• Find out more about how they work here.

For comparison, regular heat pumps supply water at 45°C to 55°C. However, they are catching up, with an increasing number of models reaching 60°C to 65°C.

Because of this fact and their usually superior refrigerants, high temperature heat pumps are now usually just as efficient as low-temperature heat pumps.

A spokesperson for high temperature heat pump manufacturer Vattenfall told The Eco Experts: “The system is almost three times as efficient as a central heating boiler,” and this sentiment was backed up by a recent government report.

Unfortunately, our most recent (2023) National Home Energy Survey found that only 51% of people are aware of heat pumps, let alone high-temperature ones. However, this is likely to change in the future.

How do high temperature heat pumps work?

There are four main ways in which high temperature heat pumps work, either through their design or components, and they are as follows.

 Optimised refrigerants

The most modern refrigerants can produce higher output temperatures in machines that use altered pressures and temperatures, though this reduces the overall heat produced by a heat pump.

That means the efficiency rate of a high temperature heat pump that works this way will be lower than that of a standard heat pump.

An Associate Professor at Nottingham University, Christopher Wood told The Eco Experts: “A refrigerant is a liquid that conveniently evaporates at a certain temperature.”

“With conventional refrigerants, the efficiency drops dramatically as the temperature goes higher. That is a function of the process,” he added.

“The pursuit of a high temperature heat pump is the pursuit of a refrigerant that can do this at a higher temperature,” he explained.

Cascade system with two refrigeration cycles

Cascade heat pumps use two cycles – one low and one high temperature – with a different refrigerant. In the low-temperature cycle, the refrigerant evaporates at an extremely low temperature and condenses in the heat exchanger at a relatively low pressure and temperature.

This allows heat to move to the evaporator, which makes the second refrigerant evaporate as well. The second refrigerant then condenses at a still relatively low pressure, keeping the output high.

Enhanced Vapour Injection (EVI)

EVI involves adding another loop to the heat pump cycle, which allows a small fraction of condensed refrigerant to leave through an expansion valve, into a counter flow heat exchanger.

This results in a superheated vapour that can then be injected into the compressor, increasing the heating capacity. You’ll use more electricity this way, but it’ll also increase the machine’s efficiency.

Natural refrigerants and sorption products

These are gas-fuelled high temperature heat pumps that use a sorbent to absorb refrigerant vapour and create a new solution.

This solution is pumped up at the same pressure as the condenser, and the refrigerant is extracted from the sorbent and put into the generator through heating.

However, this type of high temperature heat pump is not available to domestic properties in the UK.

Pros and cons of high temperature heat pumps

The first major difference is the cost. Depending on the type and size installed, a high-temperature heat pump will cost between £11,000 and £42,500. Also, depending on the system installed, a regular “low-temperature” heat pump will cost between £2,400 and £14,000.

However, they are usually more efficient than their low-temperature counterparts. Their higher Coefficient of Performance (COP) means you use less electricity to get the heat output required.

This means you’ll likely spend roughly the same on your energy bills – but you won’t have to install new radiators or insulation.

This is especially the case the more you use it over time.

High temperature heat pump costs

High temperature heat pumps cost £11,000 for the average three-bedroom household, including purchase and installation.

This is 10% more than an air source heat pump costs on average, and more than double the price you’ll pay for a gas boiler.

On the other hand, you’ll future-proof your house against a potential gas boiler ban, and you won’t have to get new insulation or radiators to do it.

Which high temperature heat pumps are available in the UK?

At present, the two major players on the high temperature heat pump seen are:

• Daikin’s Altherma 3H HT – available in 6-12 kW models, can supply water up to 65°C.
• Trianco’s Activair High Temperature Heat Pump is available in 9kW, 15 kW, or 22kW models.

Vattenfall is also set to bring its high temperature heat pumps to the UK. The Swedish state owns the company, which has already rolled out its 60°C to 80°C machines in the Netherlands.

Vattenfall’s commercial director, Mark Anderson, said: “The high temperature heat pump solution is innovative, simple to install and could be the solution to help decarbonise homes in the UK that are heated using traditional gas boilers.”

Will I benefit from installing a high-temperature heat pump?

In short, yes, because most homes are suitable for high-temperature heat pumps, you will likely benefit from using one long-term. This is especially true if you have a gas boiler and can’t change your radiators or add insulation. 

• If you live in a listed building or another type of home that is difficult to insulate, high temperature heat pumps can work very well. 

• You can still insulate your home and cut your energy bills and carbon emissions even further.

• Even though they are 10% more expensive, most UK homes would need new radiators and insulation to get a regular one. Getting a high temperature one could be cheaper in the long run.

• Their superior refrigerant and weather compensation controls mean they work in more extreme temperatures than regular heat pumps – they will work even if it is -28C outside.
• High temperature heat pumps can continue functioning at air temperatures as low as -28°C, while regular heat pumps usually work at -10°C and can even tolerate -25°C, depending on the model. Heat pumps work excellently in hot weather.

How do I know if my property is suitable for a high temperature heat pump?

Most homes are suitable for a high temperature heat pump.

If your property currently has a gas boiler and you’re unable or unwilling to change your radiators or add insulation, a high temperature heat pump could be the perfect solution.

They’re also a good option for listed buildings, properties which aren’t connected to the gas grid, and homes that are extremely difficult to insulate.

Replacing a gas boiler with a high temperature heat pump is also relatively straightforward, and it places you at the cutting edge technologically.

But whatever your decision, we’d still recommend insulating your home as much as you can, as it’s the quickest, most cost-effective way to improve your property’s energy efficiency and cut your heating bills.

Summary and next steps

• High temperature heat pumps are exciting pieces of technology for domestic heating and hot water.
• They are beefier units than heat pumps you might be more familiar with but offer superior efficiency and heating capacity.
• While they are costlier to install than “low temperature” heat pumps, their superior efficiency means you’ll get your money back quickly.
• High temperature heat pumps are the best option for many homes, but it all depends on your property.
• They cost about the same to run, and Nottingham University’s Dr Wood told us, “There’s no reason why technological advances can’t be made in this field.”
• If you want to see how much a heat pump would cost, try our custom-built tool. Pop in a few details and our professional suppliers will get in touch with their best prices.