PHPI catches up with plumbing and heating engineer Tom Smith to see how a heat pump and underfloor heating combined at a Cornish self-build.
One of the ways to get the best out of a heat pump is to pair it with the right heat emitter. Underfloor heating systems are suited to low temperature systems like heat pumps because they provide a large surface area through which the system can transfer heat into the room. When set correctly, underfloor heating can achieve and maintain desired room temperatures allowing the heat pump to operate at its best, in an even, balanced cycle.
This was the logic behind a recent self-build project on the outskirts of Truro in Cornwall. The homeowners wanted a heating system that would deliver consistent comfort but with minimal energy use. In 2024, Tom Smith of Tom Smith Plumbing & Heating and Greenwave Renewables SW Ltd took on the project, managing all aspects of the plumbing, heating, mechanical and electrical installation. Working alongside Grant UK, Tom and his team developed a full-spec, whole house heating solution built around low-carbon technologies.
“When we started this project, it was clear that we needed to deliver a heating system that would be ultra energy efficient,” explained 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.”
Tom combined and installed a heat pump, hot water cylinder, underfloor heating and solar thermal system, all products designed to work together and complement one another to deliver the maximum efficiency for the client.
Heart of the system
At the heart of the system is a Grant Aerona 290 9kW air-to-water heat pump. But to maximise the heat pump’s performance, it was crucial to pair it with heat emitters that suited a low flow temperature. Underfloor heating was installed throughout the property using two types of Grant’s Uflex UFH systems.
On the ground floor, a traditional screeded system was used with 16mm Uflex pipe laid into the floor structure. Upstairs, where a screed was not suitable, a dry-fitted Uflex Overlay UFH system was chosen. This system also uses 16mm Uflex pipe, but the pipework is slotted into pre-formed grooves in lightweight boards which are then covered with the finished floor surface, no wet trades required.
Open loop
Working alongside Neil Sawers, Grant UK’s Commercial Technical Manager, and their Design Team, Tom was able to design an almost fully open looped system with only the bathrooms being thermostat controlled. By opting for an open loop heating system, a uniform temperature of between 21ºC to 22ºC was achieved throughout the whole house rather than the homeowners having to manage lots of different zones with varying temperatures.
“The combination of the Aerona 290 heat pump with Grant hot water cylinder, solar thermal and UFH systems 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 to 22ºC throughout the 365 days of the year,” explained Tom.
