A self-build property in Cornwall is being kept warm by a Grant whole house heating system which includes a R290 air source heat pump, high efficiency hot water cylinder, a solar thermal system and underfloor heating. Working closely with Grant UK’s Specification and Sales Teams, the G1 installing engineer delivered a complete renewable heating system installation for their eco-conscious client.
The Project
Property: self-build domestic
Heat source: air source heat pump
Products installed: Aerona 290 9kW air source heat pump, QR 300ltr Twin Coil Cylinder, two panel Grant Solar Thermal System, Uflex underfloor heating and Uflex Overlay underfloor heating systems.
In 2024, Tom Smith of Tom Smith Plumbing & Heating and Greenwave Renewables SW Ltd, commenced a project with a self-build property located on the outskirts of Truro, Cornwall. The client wanted their new home to be as sustainable as possible with Tom and his team managing the plumbing, heating, mechanical and electrical side of the project. As a G1 Installer, Tom worked closely with Grant UK’s Design and Specification Team, Sales Team and Technical Department to develop a whole house heating system that would fulfil the property’s heating and hot water requirements.
Renewable heating system for self-build
The build project started in 2024 with Tom and his team completing the plumbing and heating systems by early Summer 2025. Comprising of 4-5 bedrooms, the property is set in its own grounds and is a full Passive house, using exceptional levels of insulation, airtight construction and a mechanical ventilation system which have created a home which is incredibly energy efficient. The property’s owner wanted their new home to be self-sufficient as well as being heated by renewable energy so Tom had a clear brief when he started designing the systems to suit this home.
“When we started this project, it was clear that we needed to deliver a heating system that would be ultra energy efficient,” explains Tom. “This is why we worked closely with Grant UK to incorporate their latest heating technologies which would not only meet the heating and hot water demand of the household but do so in such a way that little energy input would be needed. By using the heat pump, hot water cylinder, underfloor heating and solar thermal system all supplied by Grant UK, we knew we were installing products that had been designed to work together and complement one another to deliver the maximum efficiency for our client.”
R290 air source heat pump
At the heart of the heating system is an Aerona 290 9kW air-to-water heat pump, Grant’s fifth and latest generation of heat pumps which uses the more environmentally friendly R290 refrigerant. This R290 heat pump incorporates many features which suit a self-build property, including:
- Sleek design with powder-coated casing
- Incredible efficiencies with a SCOP of 4.74 (at 35ºC water temperature)
- Very low sound levels when operating with Quiet Mark accreditation
- Available with 7 year guarantee when installed by a G1 Installer (Terms and Conditions apply)
Maximising heat pump efficiency
With the home’s insultation levels designed to Passive standards, the heat loss for the property was calculated at 6.66kW. Tom therefore looked at other ways he could support the heat pump’s operation to be as efficient as possible.
“Working alongside Neil Sawers (Commercial Technical Manager at Grant UK) and Grant UK’s in-house Design Team,” continues Tom, “we designed an almost fully open looped system with only the bathrooms being thermostat controlled. By opting for an open loop heating system, we could achieve a uniform temperature of between 21ºC-22ºC throughout the whole house rather than micromanaging lots of different zones with varying temperatures which can reduce the overall efficiency of a heat pump. Our client will still enjoy their desired room temperatures but the absence of multiple zones has allowed us to set the flow temperature from the heat pump to 45ºC (outside temperature designed at -2ºC) and this has resulted in the Aerona 290 heat pump already achieving respectable hot water and heating coefficient of performance (COP) readings.”
Interested in learning more about open loop heating systems for heat pumps? Please contact our Design Team who can assist with queries relating to designing and specifying a new heat pump heating system.
Smart heat pump system controls
To control the Aerona 290 heat pump, an Aerona Smart Heat Pump system controller has been installed which also combines eye-catching aesthetics with first class functionality. For this self-build property, this smart heat pump controller is providing:
- User-friendly navigation via the clear visuals and menu on the controller’s 4.5” colour touchscreen display
- Straightforward control of the heating and hot water schedules which can be set and adjusted with ease through weekly or daily timed programming
- Remote access of the controller, allowing the homeowner to adjust their settings using a supporting app when away from the property.
“This was my first time installing the Aerona Smart Controller and it is incredibly intuitive,” says Tom. “You can do a lot more with this controller, such as adjusting the heating curve, and this will help us to maximise the efficiency all year round. I’ve shown the homeowner how to use the controls as part of our handover and using the remote monitoring and management features, I am hoping I can help the system to achieve even greater efficiencies through improved weather compensation and adjustments.”
Selecting the right heat emitter for this self-build
Another way of supporting the efficient operation of the Aerona 290 heat pump was to ensure that the heat emitters were correctly sized. With air source heat pumps operating more efficiently when they have lower flow temperatures, the heat emitters need to have a larger surface area to effectively transfer the heat from the system into the rooms. This is why underfloor heating works so well with heat pumps and why underfloor heating (UFH) was installed throughout this self-build property.
Grant UK supply a range of underfloor heating systems which can suit different applications within one property. For this installation, Tom installed two types of underfloor heating systems:
- Uflex UFH system installed downstairs – (pictured above) with this UFH system, the 16mm Uflex pipe was laid as part of the floor construction using a traditional screed.
- Uflex Overlay UFH system installed upstairs – (pictured below) this UFH system also uses the 16mm Uflex pipe but instead of laying the pipework within approximately 75mm of screed, the pipe is positioned into place using pre-formed groves in lightweight boards. With the Uflex Overlay Board UFH system, no screed is required and the floor covering can be laid directly on top.
Solar thermal system for DHW
The Grant Aerona 290 heat pump installed at this property will be fulfilling its space heating and domestic hot water (DHW) demand. To support the production of hot water, a Grant solar thermal system has also been installed which will capture the heat energy from the sun and transfer this into useable energy within the heating system for DHW production. A two panel, in-roof solar thermal system has been fitted which was easily integrated as part of the property’s roof during the early stages of the build. By fulfilling a significant proportion of the DHW production, this solar thermal system will reduce the demand on the heat pump, further supporting the overall efficiency of the entire heating system.
Please visit our Education Area to learn more about how solar thermal hot water systems work.
Self-build hot water storage solution
With both the heat pump and solar thermal system working to fulfil the hot water demand, a twin coil hot water cylinder was required for this property. A Grant QR Twin Coil 300ltr Cylinder was installed which incorporates two internal coils – one which is connected to the heat pump and a second coil which is connected to the solar thermal system. The heat generated by both of these renewable fuel sources is therefore transferred into and combined within a single cylinder.
The Grant QR Twin Coil hot water cylinder has:
- 25 year material guarantee on the cylinder shell (Terms and Conditions apply)
- A high quality duplex stainless shell
- Large stainless steel internal coils
- A factory-fitted 3kW immersion heater
Other systems and products installed on-site
Alongside the Grant products which complete the heating system, Tom and his team also installed other systems at this property to support its self-sufficient operation. These included a fully integrated mechanical ventilation system installed in the plant room, a 12kW solar PV system with 20kW battery storage for electricity production, and a 5,500 litre rainwater harvesting tank.
Installer’s feedback
With their client happy with their new Grant renewable heating system keeping their self-build home warm, Tom Smith shares his summary from the installation project.
“I absolutely love the Aerona 290 heat pump unit,” Tom explains. “It is a much better looking heat pump compared to older models and probably one of the best looking heat pumps on the market today. And, with it being Grant’s latest generation of heat pump, I was keen to install it at this property in Truro because it met the high standards we were achieving at the build.
“The combination of the Aerona 290 heat pump with Grant hot water cylinder, solar thermal and UFH system as well as the other features of the property, has resulted in a home which is not only extremely energy efficient but it will have low energy consumption while providing hot water and a constant temperature of between 21ºC-22ºC throughout the 365 days of the year. We also expect this house to be self-sufficient for almost 12 months a year. Having the on-site support from Shaun McCarthy, one of Grant UK’s Technical Sales Support Engineers, was also invaluable when we were setting up and commissioning the heat pump system.”
Please click here to view more photos from this installation.
Resources for self-builders
If you are a planning a self-build project and looking for a low-carbon heating system for your property, here are some useful resources to support your research:
- Learn about how air source heat pumps work in our Education Area
- Read about R290 heat pumps, underfloor heating and radiators in our Tips & Advice zone
- Discover more about Grant’s complete range of package heating solutions.