Do Heat Pumps Work in Old or Poorly-Insulated Homes? | EcoSphere Energy
Do Heat Pumps Work in Older or Poorly-Insulated Homes?
The most common concern we hear — and the answer is almost always yes, with the right design. Here’s what you need to know.
Yes, in the vast majority of cases. Modern heat pumps are designed for the UK climate and UK building stock — including solid-wall homes, stone cottages, and period properties. What matters is correct sizing, not a Passivhaus EPC.
The key: right-sizing the system
A heat pump designed to meet the actual heat demand of your home will perform well regardless of wall construction. The MCS heat loss survey we carry out on every project calculates how much heat each room needs on the coldest design day (−3°C for Devon). The system is then sized to meet that demand — it doesn’t matter whether your walls are insulated or not; it matters that the heat pump and emitters are big enough to deliver.
Common concerns addressed
“My house is too cold / too draughty”
A higher heat loss means a larger heat pump and more or bigger radiators — all of which we size correctly in the design. A draughty house costs more to heat (regardless of fuel), but a correctly-sized heat pump handles it just as a larger boiler would.
“Heat pumps don’t work in cold weather”
Modern air source heat pumps operate efficiently down to −10°C and continue working (at reduced output) to −25°C. Devon rarely sees temperatures below −5°C, making this a non-issue for our region.
“My radiators are too small”
Heat pumps work best at lower flow temperatures (40–50°C vs 70–80°C for a boiler). We assess every radiator in the property and identify which (if any) need upsizing. In many homes, only a handful need replacing; modern heat pump radiators are not dramatically larger than standard ones.
“Listed or heritage homes can’t have heat pumps”
Listed building consent is sometimes required for external units, but many listed buildings in Devon and Somerset have been successfully fitted with heat pumps. We can advise on planning and consent requirements as part of your quotation.
Do you need to insulate first?
Not necessarily. While better insulation reduces running costs, there is no minimum EPC requirement for the BUS grant (removed April 2026). We will always highlight where straightforward insulation improvements (loft, cavity, draught-proofing) would reduce your running costs — but they’re not a prerequisite.
Some installers recommend wall insulation before a heat pump to reduce system size and cost; others prefer to right-size the heat pump to the home as-is. We’ll discuss both approaches and give you a clear recommendation based on your specific property.
Let’s Assess Your Home
A free heat loss survey is the definitive answer to whether a heat pump will work well in your property — and what it will cost to run.
Book a free heat loss surveyHeat Pump Installers Across the South West
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