Do heat pumps work in old houses? Almost always, yes

People ask me this every week. Do heat pumps work in old houses? Almost always, yes. And the age of the house is rarely the reason it does or doesn’t.

Here is the thing most people have backwards. A heat pump doesn’t care what year your house was built. It cares how fast the house loses heat. Those are two different things, and somewhere along the way we started treating them as the same thing.

I’ve fitted a heat pump in a solid-wall Victorian terrace in Tunbridge Wells with the original sash windows still in. It’s warm. The bills went down. In the same month I walked out of a five-year-old house near Ashford and told them to sort the loft before they spent a penny on heating, because it was losing warmth like a bucket with a hole in it. New doesn’t mean tight. Old doesn’t mean draughty. You have to actually go and look.

What matters is heat loss. If your house holds onto heat, a heat pump can keep up without trying hard. It ticks along at a low water temperature, and that low temperature is the whole trick. It’s the difference between a cheap heat pump and an expensive one. If your house loses heat fast, the pump has to run hotter to keep pace, and that is exactly when people get the frightening bills and decide the technology doesn’t work. It wasn’t the technology. It was the house.

So an old house isn’t a problem to be solved. It’s just a house that needs looking at properly. And the good news is that most old Kent homes can be made to hold heat well without ripping the character out of them.

Usually it’s the boring stuff that does the most. Draught-proofing round the doors and floorboards. A decent layer in the loft. Filling the obvious gaps. None of it is glamorous and none of it costs much, but it quietly changes the numbers more than people expect. Sometimes we’ll swap a couple of the smaller radiators for bigger ones so the system can run cooler. That’s not the pump struggling. That’s us setting it up to sip energy instead of gulping it.

The myth I’d most like to kill is that you have to gut the place. Rip out every radiator, dig up the floors, triple glaze the lot. I’ve had people brace themselves for that and I’ve had to talk them down. Most of the time it isn’t true. A proper heat-loss survey, the kind that measures your actual house rather than guesses, nearly always finds more of your existing setup is fine than you feared.

Here’s the part that surprises people. The hardest house I’ve ever heated wasn’t the oldest. It was a modern one. Big, open, full of glass, thrown up quickly with insulation that looked fine on paper and wasn’t. The oast house down the lane, three hundred years old, was easier. Thick walls hold heat, and heat is the thing we’re trying to keep hold of.

None of this means every old house is ready tomorrow. Some genuinely need work first, and I’ll tell you plainly if yours is one of them. I’d rather lose the job than fit a heat pump into a house that will fight it every winter. But those houses are rarer than the internet makes out, and the reason is almost never the date on the deeds.

If you’ve got an old place and you’ve been told a heat pump won’t work in it, be a little suspicious of whoever told you. Ask them about the heat loss, not the age. That one question tells you whether they’ve understood your house or just glanced at it. And if you want someone to actually measure it, that’s the part of installing a heat pump I care about most, because everything else follows from getting it right.