Daikin Altherma air source heat pump review by Andrew Gage

Daikin Altherma Air Source Heat Pump

Photo: The outdoor fan unit of the Daikin Altherma High Temperature ASHP

The Gage family chose to install the Daikin Altherma when retrofitting their 1920s detached home. Here Andrew shares their experience of the product.

Daikin Altherma High Temperature air source heat pump

The Daikin Altherma High Temperature air source heat pump (ASHP) provides space heating and hot water to your home. It is an ideal replacement for a traditional boiler because it connects seamlessly to your existing pipe network and standard high temperature radiators. Its two main components consist of an outdoor and indoor unit. The outdoor unit takes heat from the ambient air and transfers it via a refrigerant pipe to the indoor unit which then uses it to warm the water in your heating system. The system promises to deliver a water flow temperature of up to 80°C for central heating networks.

Andrews says…

It is extremely effective at its job, keeping the house warm and supplying sufficient water to simultaneously service two hot showers

In 2011 we decided to add an ASHP to the long list of energy efficiency measures we have made to our home, as part of our motivation to lead a more sustainable and low carbon life. The model we chose was the 11 kW Highlight Daikin Altherma. It provides Highlight domestic hot water and space heating. It is extremely effective at its job, keeping the house warm and supplying sufficient water to simultaneously service two hot showers. The Daikin has been connected effortlessly to our 4kW solar panel system. When the sun is shining and the PV system is generating us electricity, the ASHP is effectively running at no, or low, cost.


The company continue to provide annual inspections and are very reliable.

After much difficulty, we found our installer H2O Renewable Energy Solutions, through a casual conversation with a tradesman who was working at our house at the time. The installer spoke at length about the product and the type of ASHP that would be most suitable for our home and heating needs. This began a trusting relationship between us and installer that has continued to endure to this day.

We decided to locate the internal units, including the hydro box boiler and hot water cylinder tank, in our recently extended garage. The external fan unit was fitted directly outside on the other side of the wall. The installation took one month to complete and worked alongside a considerable building and renovation project we were undertaking. The final cost of the product and labor was £11,000, however this is not a truly accurate reflection of the cost as I fitted much of the internal pipe work myself.

It is fair to say that H20 Renewable Energy Solutions have been a delight to work with. We are extremely happy with their level of service and the support they have given us. The company continues to offer advice and can always be called upon if we incur any problems.

Main benefits

We really appreciate the ease of having hot water when we need it and not being cold inside the house.

The main advantage of the Daikin ASHP is that the house is always as warm as we wish, 24 hours a day, even in the coldest of winters. As all our rooms are warm we aim to keep all the doors open, when convenient, to allow the heat to circulate throughout the house. Similarly, the heat pump also provides more than enough hot water to meet our daily requirements. With three adults and two children who regularly shower or bathe twice a day, meeting this requirement was a must! Now comfort is a standard and we no longer need to worry about putting on extra layers to keep warm.

It is hard to determine how much energy we have saved since installing the Daikin Altherma. I have been keeping a record of our electricity use, but as we had an inefficient gas boiler for only one year before the installation, it is impossible to accurately compare. However, given the heat pump’s high efficiency rate and green credentials, it’s very likely that significant energy savings have been made.

Practical details

Carbon reduction was the principle reason for its installation

The product is efficient, performs well, responds quickly and is very reliable. In the 5 years of its operation, we haven’t experienced any problems apart from a few teething issues immediately after its installation and one short lived fault.

Since the installation, we believe our heating bills are much lower than expected for a house the size of ours (1920s six bedroom detached brick property). The heat pump also qualifies for the government’s domestic Renewable Heat Incentive. This means we receive quarterly cash payments for simply using the technology – what’s not to like? We have received £7,500 over the first five years of using the product and expect at least 68% of the cost to eventually be refunded. Having a financial pay back really gives an added bonus to the carbon savings you know you are making!

The Daikin comes with a three year guarantee, including parts and labor. When purchasing the product ourHighlight  installer told us that it is likely to last about 15 to 20 years. However, as this type of technology is advancing rapidly, we will look to have some modifications fitted in the future to extend its life.


We have always used gas boilers but this is much better!

Our top three considerations when comparing ASHPs is their efficiency, green benefits and price, with price being the most important. What we didn’t originally consider, but later came to realise its great importance, is the customer care the installer offers. Our installer introduced us to the Daikin, and gave us clear answers to our questions and placed no pressure on us to purchase the product.

The only way we feel the performance of the product can be enhanced is by connecting it to an under floor heating system. We had already begun the large extension to the house before we decided we wanted an ASHP. Unfortunately we therefore didn’t consider the technicalities of such a system and laid a concrete floor in the extended areas. This has meant that we have had to adapt to using radiators, which is not our first choice, but one that still works very well. If we were to go back in time and make any changes, we would be sure to design the refurbishment to tailor the practicalities of using an ASHP in this way.

Specific questions

No planning permission was required

The heat pump is our main source of space heating and always keeps the house no cooler than a temperature of 18°C. If we do incur any breakdowns or faults we have a gas fire and fan heaters that can serve as a backup.

Heat pumps are often only recommended for very well insulated properties and it is important to note that the insulation we have fitted throughout our house contributes to the excellent benefits the Daikin gives us. In our case we have fitted a variety of measures that include triple glazing, thermal backed plasterboard, cavity wall insulation and 260mm loft insulation. These technologies can work hand in hand to maximise the benefits of any retrofit, so we would highly recommend both if you’re considering a similar project.

In terms of size, the Daikin’s hot water and space heating tanks require roughly 2.5m2 floor space, the compressors need about 1m2, and the external fan unit 0.5m2. The components of this system require an annual maintenance check. It is quite a complex job so I pay our installer a fee of £60 per annum for the service.

Product details: Daikin Altherma
Manufacturer: Daikin \
Installer: H2O Renewable Energy Solutions
Owner case study: SuperHome 107


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