Reality Check · August 2026
Combined Heat Pump + Underfloor Heating Costs – How the Systems Interact
Why the two systems work well together, what public data shows on cost, and how the Combined calculator builds the planning figure.
Quick Answer
When you put an air source heat pump with underfloor heating the two systems work together. The heat pump can run at a lower flow temperature, which improves efficiency. Public price ranges for a combined install typically sit higher than either system alone because you are doing both, but the running cost benefit is real.
Our Combined calculator already starts from the ASHP and UFH planning bands and then applies the realistic total for Devon and Cornwall properties, including shared design work and the efficiency of a properly matched low-temperature system. That is why the figures sit where they do.
Why the systems work well together
Underfloor heating needs lower water temperatures than traditional radiators. A heat pump prefers lower water temperatures. Put the two together and the heat pump can run in its more efficient range for more of the year.
Field data backs this. Underfloor systems in UK trials commonly achieve SCOPs around 3.7, while radiator-only systems sit lower. The calculator already uses that conservative UFH baseline when underfloor is the main emitter.
What the combined cost looks like
You are paying for two systems. The heat pump (design, unit, cylinder, electrics, MCS) plus the underfloor heating (boards or screed, pipe, manifold, labour). There is some shared design and commissioning work, but the materials and labour still add up.
Public ranges for a full combined install often land between roughly £15,000 and £30,000 before the BUS grant, depending on the size of the heat pump, the area of underfloor heating and the system path (screed is usually cheaper than overlay when the floor is open).
The Combined calculator starts from the same locked ASHP capacity bands and UFH system paths already validated in the individual Reality Checks, then shows the realistic total for a combined project.
How the Combined calculator treats the interaction
It does not invent new numbers. It uses the same public-price foundations and professional allowances already used for the heat pump and the underfloor heating separately. The difference is that it shows both systems together and applies the efficiency benefit of lower flow temperatures when underfloor is the main emitter.
That keeps the planning figure consistent with the individual calculators and with the real-world SCOP data. The figure is still a planning band, not a fixed quote. A proper survey will refine it for the actual house.
South West notes
Floor height is often the practical limit on older Devon and Cornwall properties. Screed may not be possible without major disruption. Overlay or structural board paths cost more per square metre but keep the height rise low. The Combined calculator already offers the same system paths as the dedicated UFH tool so the height reality is reflected in the planning band.
See the combined planning band for your home
The free Combined Passport already uses the locked ASHP and UFH bands and the conservative efficiency assumptions. No obligation. Every submission is personally reviewed.
Start Combined Passport →Frequently asked questions
Is underfloor heating better with a heat pump?
Yes for efficiency. Underfloor heating runs at lower flow temperatures, which improves the heat pump’s SCOP. Field data shows UFH systems often achieve around 3.7 compared with lower figures for radiator-only systems.
How does the Combined calculator treat ASHP + UFH?
It starts from the same locked ASHP capacity bands and UFH system paths already validated, then shows the realistic total for a combined project including shared design and the efficiency benefit of lower flow temperatures.
Will the combined cost be less than doing the two systems separately?
There is some shared design and commissioning work, but you are still installing two systems. The Combined calculator shows the realistic total rather than an artificial discount.