The most common reason people rule out a heat pump before they’ve even had a survey is the age of their home. If the house is old, they assume it won’t work.
It’s worth unpicking that assumption, because it’s costing people money.
Does house age affect heat pump suitability?
Age isn’t the issue. Heat loss is.
A heat pump doesn’t care when your house was built. What it cares about is how much heat the building loses on a cold day, and whether the system can be designed to replace that heat efficiently.
Suitability comes down to a heat loss calculation, not the age of the property. I’ve surveyed modern houses with poor fabric performance and old houses that, once you understand the construction, are perfectly workable for a heat pump. The property I’m going to tell you about is a good example of both the challenge and what’s possible when the design is done properly.
The property: 1700s solid-wall house in Cheshire
John’s house in Cheshire dates to the 1760s. The core is sandstone, with additions built in 1917, 1975, and post-2005. So you’ve got four different construction eras under one roof, solid walls throughout the original section, and a building that had been heated by oil for years.
One section of the house had always been cold and damp, which is exactly what you’d expect from that kind of construction with that kind of heating.
The 2000 litre oil tank was a concern; it was 30 years old and single-skin steel with no bonding, and it needed replacing. John was really worried about it leaking.
On paper, this is the property people point to when they say heat pumps won’t work in old houses. But nothing could be further from the truth.
What I knew going in
Solid wall construction loses more heat than a cavity wall with insulation. That’s not a reason to rule out a heat pump. It’s a reason to do an accurate heat loss calculation and design the system around what the building actually needs.
The 1975 extension was more straightforward. The 1917 section needed more attention. The 1760s sandstone core is the kind of fabric that takes time to understand properly, because sandstone behaves differently to brick. It absorbs moisture and releases it. It has thermal mass. You don’t treat it the same way.
We sized the system to handle the whole property on a cold day, specified the right emitters, and designed for low flow temperatures. That last part matters more than most people realise. Heat pumps are most efficient at low flow temperatures, typically 35 to 45 degrees. Getting there in an old property means the radiators and pipework have to be up to the job. Where they weren’t, we dealt with it.
Year one results: the real figures
John filmed a follow-up with Heat Geek twelve months after installation. The numbers from that year:
- 3,982 kWh for heating and hot water across the full year
- £836 in running costs, on John’s actual tariff
- 520% efficiency across the year
- Previously spending an estimated £1,200 to £1,500 per year on oil
That’s a saving of roughly £400 to £650 a year in running costs, in a 1700s solid-wall property that people would typically write off as unsuitable. The section of the house that had always been cold and damp is now warm and dry.
See the results for yourself
John filmed a follow-up with Heat Geek twelve months after installation. Watch the full video below.
Credit: Heat Geek — “Oil Crisis Averted, The Heat Pump That Saved This 1700’s Home”
Is your home suitable?
The honest answer is that I don’t know until I’ve looked at it. What I can tell you is that we can heat ANY home with one or more heat pumps. In rare cases, there is a point where the upfront cost associated with installing a heat pump in a very high heat loss home becomes prohibitive. However, it’s important to say that these houses are usually very expensive to heat, so the potential savings long-term can be much higher.
For most people, a single heat pump installed on a carefully designed system at a reasonable cost will happily heat their house at efficiencies that beat today’s oil and gas prices.
I can tell you is that age alone isn’t a disqualifier. Solid walls aren’t a disqualifier. Oil heating isn’t a disqualifier.
If you’ve been told your house is too old for a heat pump, or you’ve assumed it yourself, it’s worth getting a proper heat loss survey before writing it off.
Hohm is MCS certified and RECC registered. We cover Cheshire and the surrounding area.
Use the free Spruce estimator to get an initial cost figure, or call the team directly on 01477 531 688 to talk through your property.