Radiator upsize cost for a heat pump (UK 2026)

Radiator upsize cost for a heat pump (UK 2026). The published installed range in 2026 is £1,800 to £4,500 for a full set of upsized radiators in a 3-bed (MCS and Heat Geek publisher). Both ends of that range are stated rather than collapsed to a midpoint, because the spread reflects real differences in scope, access and grant eligibility rather than installer mark-up.

• Number of rooms; the kitchen and bathroom often retain existing emitters.
• Pipework upsize from 8mm or 10mm microbore to 15mm or 22mm.
• Hidden access cost in solid-floor properties.
• Underfloor heating retrofit is a different exercise at £80 to £140 per m².

Paired with the ASHP install at design stage, not after.