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Prospect House Underfloor Heating Case study
- Client - Homeowner
- Underfloor heating Throughout
- 35°C Flow temperature - Perfect for heat pumps
- Screeded underfloor heating on the ground floor - Between joist system on the first floor
Requirements
Design and insall underfloor heating throughout with no build up on the first floor.
Heat Source
Vaillant Arotherm Air Source Heat Pump
Flow Temperature
35°C
Underfloor Heating System
60m² Screeded ground floor - 60m² Between joist first floor
Initial survey and design
- When asked to provide a quotation for this Prospect House, we were excited to get involved. The homeowners’ primary aim was a highly energy-efficient system that delivered comfortable living temperatures. The ground floor would receive screed as part of the build, while the first floor already had floorboards but was accessible from below. With a Vaillant air‑source heat pump as the heat source, we designed the system with a 35°C flow temperature to minimise running costs. Case study to follow.
.png?width=1024&height=1024&name=Untitled%20design%20(1).png "Untitled design (1)")
Ground floor solution
- The ground floor received 200 mm of Kingspan insulation over the concrete slab, topped with a Superfoil vapour barrier to add reflective properties and protect the Kingspan from screed damage. We confirmed the kitchen layout and marked areas where underfloor heating would not be installed, then fitted a foam perimeter strip to accommodate thermal expansion and protect the screed. After the preparatory work, we installed 16 mm PERT/AL/PERT pipe at 125 mm centres and connected it to a stainless-steel manifold. Following a pressure test, the system was filled with water, biocide and inhibitors to prevent corrosion and extend its lifespan.
.png?width=970&height=600&name=Untitled%20design%20(8).png "Untitled design (8)")
First Floor Solution
- The first-floor boards were already glued down so taking them up wasn't much of an option. We installed a fit-from-below between-joist system, which was ideal for this situation. Aluminum spreader plates were fixed to the underside of the floorboards, and 16mm PERT/AL/PERT pipe was routed through the joist cavities and clipped into the plates. Although installation was challenging—made more complex by the existing sprinkler system—the finished underfloor heating performs exceptionally and looks great.
.png?width=849&height=525&name=Untitled%20design%20(7).png "Untitled design (7)")
End Result
- The completed project delivered an efficient, whole-house wet underfloor heating system tailored for an energy‑savvy client who prioritised low running temperatures and long‑term savings. Our bespoke design ensured accurate heat‑loss calculations, correctly sized manifolds and tightly zoned circuits to maintain consistent comfort while operating at reduced flow temperatures compatible with heat pump integration. High‑performance insulation and carefully specified floor coverings maximised heat transfer and minimised losses, resulting in rapid, even warmth and significantly fewer cold spots than the property’s previous radiator system. Commissioning and thermostat zoning were fine-tuned on site to balance responsiveness with energy saving, and the client received clear handover documentation and guidance on optimising controls for daily use. The final outcome was a discreet, reliable system that reduced visual clutter by removing redundant radiators, freed wall space, and improved overall comfort throughout the home. Early monitoring and homeowner feedback confirmed lower energy use and steady temperatures across living spaces, validating the low-temperature approach. GT Underfloor Heating’s careful design, quality installation and post‑installation support delivered a future‑ready heating solution that meets the client’s efficiency goals while enhancing property value. For homeowners across Cardiff and South Wales seeking underfloor heating designed for low running costs and heat‑pump compatibility, this project exemplifies our practical, performance-driven approach.