Why heat pumps feel scary (and why they shouldn't)

For the full list of articles demystifying heat pumps click here

Heat pumps and why boilers make us worry about them

(Spoiler: they’re not plotting against you or your bank balance.)

Heat pumps were first used to heat homes in the 1940s, although they have only been used in large numbers in the UK relatively recently.

Air source heat pumps are the most common type. Around 100,000 are installed each year in the UK.

Heat pumps are much more common in mainland Europe, including widespread use in many colder countries such as in Scandinavia and the Baltic countries.

Contrary to one of the many myths, heat pumps work very well in the UK climate. If a heat pump system is designed and set up correctly, it will work in almost any age or size of home, with running costs that are usually lower than using a boiler. This is despite what you might read in the media.

But we are used to boilers

We are very used to them. Emotionally attached, even!

In 1970, only around 30% of UK homes had any form of central heating. Today, that figure is over 90%. The UK has one of the largest numbers of domestic gas boilers in the world (per household). In Europe, only the Netherlands has more.

This means we are very used to how boilers work. Setting fire to gas or oil gives a flame that is over 1,000°C, giving us the familiar very hot radiators. They typically heat radiators to 60°C or even 80°C — often far too hot to touch.

Feeling in control and what it means

Boilers are usually controlled by timers and thermostats. We traditionally use them to heat a home twice a day: a bit in the morning and a bit longer in the evening.

They certainly make us feel in control.

Between the morning and evening heating periods though, boiler‑heated homes start to cool down.

How quickly and how much they cool down will depend on 1) how well insulated the home is and 2) the weather.

A boiler‑heated home traditionally swings between times when it feels pretty warm (or even cosy) and then drifting into long periods where it feels less comfortable.

The cooler periods also increase the chances of condensation and mould issues.

This worked reasonably well when homes were empty during the day. But lifestyles have changed. More people are at home during the day than ever before.

We naturally worry about heat pumps because...

1. The fear of moving away from something we are familiar with and can control easily

2. Horror stories in the media about heat pumps

3. We've been brought up to believe that leaving the heating on is the most expensive way to run it. When people hear that heat pumps work best when left on 24/7, alarm bells ring.

“Surely leaving the heating on all the time must cost a fortune?”

It sounds crazy and counter‑intuitive to say that the cheapest way to use a heat pump is to let it run constantly! A lie even.

But it isn’t.

Over the course of a winter a correctly designed and set‑up heat pump will usually cost less to run than the same house with a gas boiler, and give the same or better comfort.

Next: Article 3: Why heat pumps shouldn't be treated like boilers

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Mark Thompson

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