Guide · Installation
Do I need new radiators for a heat pump?
The honest answer for UK retrofits — and the trick installers use to keep radiator costs down.
Most UK heat pump installs need 2–4 radiators uprated, not a full system replacement. Heat pumps deliver heat at 35–50°C, against 70°C+ for gas boilers, so undersized radiators in the coldest rooms get swapped for deeper double or triple panels. Underfloor heating is a bonus, not a requirement.
We’re funded by installer referral fees when you request quotes. Our editorial coverage isn’t paid for — read our editorial policy and how we rank installers.
Why flow temperature changes everything
A radiator's heat output is roughly proportional to the difference between flow temperature and room temperature. Drop flow from 70°C to 45°C and output halves. A single K1 panel that kept a bedroom warm on gas may need to become a K2 or K3 on a heat pump to deliver the same kW.
What a heat loss survey finds
Your installer's room-by-room heat loss calculation matches each radiator's rated output to that room's heat loss at the design flow temperature. Most surveys flag only the coldest rooms — typically a hallway, north-facing bedroom and the kitchen.
When you should plan for more
Single-skin extensions, conservatories and old solid-wall properties often need every radiator uprated. Add £1,500–£3,500 to your budget in those cases.
Frequently asked questions
- Do I need new radiators when fitting a heat pump?
- Usually only 2–4 radiators need uprating, not a full house swap. Heat pumps run at 35–50°C flow temperatures (vs 70°C+ for gas) so radiators need more surface area to deliver the same heat.
- How much does a radiator change cost?
- A like-for-like uprate to a deeper K2 or K3 panel costs £150–£400 per radiator including fitting. Vertical or designer radiators cost £400–£900 each.
- Energy Saving Trust — Heat pump efficiency, running cost and SCOP benchmarks (UK).
- MCS Certified — Installer certification scheme required for grant eligibility.
Start now — it’s free
Get matched with MCS-certified installers
Up to three free, no-obligation quotes from vetted local installers. 60-second form.