For years, we’ve heard a consistent refrain from homeowners on the Renewable Heating Hub forums and YouTube comments: “I’d happily switch to a heat pump… if only it didn’t wreck the house.” The UK’s decarbonisation narrative often spotlights clever compressors, smart controls and ambitious targets. But inside British homes, the real choke point is far more prosaic.
It’s the radiators.
Across the UK, 25 million homes rely on legacy radiator systems, designed for high-temperature boilers rather than low-temperature heat pumps. Retrofitting typically demands radiators 30-50% larger, a prospect that homeowners often find unappealing or impractical. No surprise, then, that according to industry data, over 80% of heat pump retrofits are cancelled or refused because of perceived disruption, cost or loss of space. That’s a staggering number!
We see this every day in comments, DMs and emails: people are interested in heat pumps (even enthusiastic) but balk at having to upend rooms, tear up flooring or fit radiators the size of surfboards. And installers tell us the same story from the other side.
As Ethan Wadsworth, Director at DiscreteHeat, puts it: “Heat pump retrofits are often sold on efficiency, but delivered with compromises. Most homes are only 100-500 watts per room short on their emitter capacity, but to bridge that small gap, we end up replacing perfectly good radiators, redesigning whole systems and creating disruption no one wants.”
This is the main frustration behind the UK’s retrofit bottleneck. Installers know that low flow temperatures are essential for achieving strong COPs, yet the pathway to get there nearly always involves upheaval. Larger radiators require two-person lifts, old units are scrapped unnecessarily and every seemingly simple job morphs into a redesign exercise often requiring floors being lifted and pipes being moved.
But what if most homes aren’t actually as incompatible with heat pumps as we assume?
When DiscreteHeat analysed years of their own heat-loss data, they found something surprising: “Over 80% of existing radiators were within about 30% of the required output for low-temperature systems,” Wadsworth told us. “Once we saw that, it became clear that full-scale radiator replacement is often unnecessary. We don’t need to tear out what’s there, we just need to supplement it.”
This insight led to the development of Add2Rad, not as a product but as a methodology, a systematic, minimal-disruption approach to strengthening emitter capacity using small, strategic additions rather than wholesale change.
“For customers that want to eliminate radiators completely, the ThermaSkirt still provides that option. But the Add2Rad approach will be the fastest, least disruptive and often lowest cost way to make an existing properties emitters optimised for heat pumps”
Add2Rad connects a short run of ThermaSkirt aluminium skirting heating in series with the existing radiator. A simple tee off the flow pipe before the TRV allows the ThermaSkirt profile to act as an extension of the radiator, boosting its output at low temperatures without altering the radiator itself.
In practice, 2-4 metres of discreet aluminium skirting typically supplies the missing wattage.
Having looked at the tech specs and product offering, the advantages, from both homeowner and installer perspectives, are hard to ignore:
- Existing radiators remain in place, maintaining the look and feel of rooms.
- Existing pipework is retained, avoiding the need to chase walls or lift floors.
- Floor coverings stay undisturbed which is a major win for homeowners.
- Waste is avoided, because working radiators are supplemented, not scrapped and sent to landfill.
- One-person installation is common, speeding up turnaround and reducing costs.
- Homes can often be made heat-pump-ready in a single day.
“We wanted something non-invasive,” Wadsworth says. “A way to give the radiator that extra 30% it needs without asking people to redesign their homes. Add2Rad makes the most of what’s already there and that’s why it works.”
From our vantage point at Renewable Heating Hub, where we engage daily with both homeowners and heating engineers, this methodology speaks directly to one of the biggest blockers in the heat-pump conversation. The technology is sound. The will is there. But the domestic realities (space, aesthetics, disruption) have too often been ignored.
By reframing the emitter challenge not as a demolition project but as a light-touch upgrade, Add2Rad suggests a way forward that acknowledges the constraints of British homes rather than bulldozing through them.
It won’t remove the need for proper heat-loss calculations, nor does it eliminate the need for thoughtful system design. But it does offer something we believe is increasingly essential: a practical, efficient and homeowner-friendly pathway to low-temperature heating.
And if the UK is serious about scaling heat pumps, solutions like this may prove every bit as important as the technologies they support.
You can find out more about ThermaSkirt and Add2Rad here.
