Underfloor Heating Running Costs: What to Expect in a Cornwall Home

The Fundamental Difference: Wet vs Electric

Underfloor heating running costs vary by a factor of 3–4x depending on whether you have wet (hydronic) or electric mat UFH, and what's powering it. This distinction matters more than almost any other factor in the running cost calculation. See our full wet vs electric UFH comparison for the installation side of this decision.

The key principle: wet UFH is a distribution system — it moves heat from your boiler or heat pump around the floor. Electric mat UFH generates heat directly by resistance. The cost of generating that heat depends entirely on your fuel/electricity tariff and, for heat pumps, the Seasonal Coefficient of Performance (SCOP).

Wet UFH With a Gas Boiler

Gas boilers work least efficiently at the low flow temperatures (35–45°C) that wet UFH requires. A modern condensing gas boiler runs at 88–92% efficiency at high flow temperatures but drops to 82–87% at UFH-level temperatures, because the flue gases don't condense as effectively. This is the reverse of the heat pump situation.

Running cost for wet UFH on gas, typical 3-bed Cornwall house, heating season (October–April):

Heating demand	Boiler efficiency	Gas rate	Seasonal heating cost
8,000 kWh	88%	6.5p/kWh	~£590
12,000 kWh	88%	6.5p/kWh	~£885
16,000 kWh	86%	6.5p/kWh	~£1,210

Gas prices are currently lower than electricity per kWh, which offsets the efficiency disadvantage versus heat pumps for properties on mains gas.

Wet UFH With a Heat Pump

This is where wet UFH delivers its greatest advantage. A heat pump running at 40°C flow temperature achieves SCOP 3.4–4.0 in Cornwall's mild climate. The same heat pump running radiators at 55°C achieves SCOP 2.6–3.0. The difference — 0.8–1.0 SCOP — is entirely down to the lower flow temperature that wet UFH enables.

Running cost for wet UFH on heat pump, typical 3-bed Cornwall house:

Heating demand	SCOP (UFH)	Electricity rate	Seasonal heating cost
8,000 kWh	3.6	24p/kWh	~£533
12,000 kWh	3.6	24p/kWh	~£800
16,000 kWh	3.4	24p/kWh	~£1,130

Despite electricity costing roughly 3.7x more per kWh than gas, the heat pump's SCOP of 3.4–3.6 with UFH means the running cost per unit of delivered heat is comparable to or lower than gas. And for off-gas Cornwall properties (previously paying 8–9p/kWh for oil), heat pump + UFH is decisively cheaper.

Electric Mat Running Costs

Electric resistance heating converts 1 kWh of electricity to 1 kWh of heat — a maximum efficiency of 100%. At 24p/kWh electricity, this is the most expensive way to heat a space. Running a 200W/m² electric mat over a 20m² kitchen for 8 hours a day costs £7.68/day in peak winter. For a full heating season (5 months, 8 hours/day), that's £1,152 for one room.

For bathroom tile warming (a 5m² mat at 120W/m² for 2 hours/day), the cost is £0.58/day or about £17/month — acceptable for the comfort benefit. At scale, electric mat heating is simply too expensive for primary room heating in most Cornwall homes.

Annual Cost Comparison by Property Size

System	2-bed (6,000 kWh demand)	3-bed (12,000 kWh)	4-bed (18,000 kWh)
Electric mat (24p/kWh)	£1,440	£2,880	£4,320
Wet UFH + gas boiler	£445	£885	£1,330
Wet UFH + heat pump (SCOP 3.5)	£410	£823	£1,234
Wet UFH + heat pump + solar	£270	£540	£810

How to Reduce UFH Running Costs

The single most effective action for reducing wet UFH running costs on a heat pump is lowering the flow temperature. If your system is set at 50°C, dropping to 40°C improves SCOP by 20–30% — potentially saving £150–£300 per year. We explain this in detail in our guide on heat pump flow temperature for UFH.

Other measures that reduce running costs: adequate floor insulation beneath the UFH (reduces downward heat loss), correct pipe spacing (200mm for living rooms, 150mm for bathrooms), and zoning the system so unoccupied rooms aren't heated.

Contact us for UFH design, installation, and heat pump integration across Cornwall. We model expected running costs at the survey stage before any work begins. See our full underfloor heating page for more.