Do you need a smart meter for a heat pump?

The short answer is no. A heat pump will run perfectly well on a forty-year-old meter with dials on it. No installation standard requires a smart meter and the Boiler Upgrade Scheme does not ask for one. The network operator's interest is in how much power the house draws, which is a separate matter from how it is metered.

The longer answer is that the question is really about tariffs, and on a heat pump the tariff is worth a lot of money.

Why the question comes up

A heat pump moves most of a household's energy use onto the electricity bill. A house heated by gas might buy 2,700 units of electricity a year and 12,000 units of gas; the same house on a heat pump buys no gas and perhaps 6,000 units of electricity. Electricity that was a quarter of the energy bill becomes all of it.

That makes the price you pay per unit of electricity matter about three times as much as it did before. And the price per unit is no longer one number for most households — it depends on the time of day, on tariffs written for houses that use a lot of electricity for heating. Being billed that way requires the supplier to know how much you used in each half hour, which requires a meter that tells them.

A smart meter saves nothing on its own. Its job is to make the cheaper tariffs available to you.

Why a heat pump is unusually good at cheap hours

Time-of-day pricing suits some appliances and not others. You cannot move when you cook or when the lights are on.

A heat pump is the opposite case, because a house and a hot water cylinder are both stores of heat. A cylinder heated at four in the morning is still hot at eight. A house warmed a degree above where you want it during a cheap block will drift down slowly over the hours that follow, particularly if it is reasonably well insulated. So a controller that knows when electricity is cheap can do a large share of the day's heating at the cheap price and coast through the expensive part.

How much that is worth depends on your house, your tariff and how much of the heating can be shifted, and it is one of the few things about a heat pump that you can change after installation without touching the hardware. Put your own rates into the running cost comparison and try it with a flat rate and with an off-peak rate; the gap between the two answers is what the meter is worth to you.

What the tariffs ask for

Suppliers offering heating tariffs generally want three things, and the third one catches people out.

A heat pump or electric heating in the property, or one on order.

A smart meter, and in practice a second-generation one. The earlier models were installed before a common national network existed, and while most have since been brought onto it, some still report unreliably. Your supplier can tell you which you have.

A meter that is working. A large number of British smart meters sit in a cupboard sending nothing, because the mobile signal is poor, or the meter lost its connection during a supplier switch and was never chased. What the tariff needs is half-hourly readings arriving at the supplier, so a meter that has stopped reporting will not qualify you. If your supplier's app has not shown you daily usage for a while, that is the symptom.

You do not need a separate meter for the heat pump

This is a common worry, and it comes from the old off-peak arrangements where storage heaters sat on their own circuit behind their own meter.

Modern heating tariffs price all the electricity in the house, so the cheap hours are cheap for the washing machine as well, and the expensive hours are expensive for the kettle. It is one meter and one bill, with the price changing through the day. That cuts both ways: a tariff with a very cheap night block usually has a dearer daytime rate to pay for it, and whether you come out ahead depends on the shape of your whole household's use, not the heat pump's alone.

A smart meter is not an upgrade to your supply

Changing the meter does nothing about how much power the house can draw. The limit is the main fuse ahead of the meter, which belongs to the network operator, and on an older property it can be 60 A or 80 A where a heat pump, a shower and a car charger together want more.

That is a real thing to check before a heat pump goes in, and the installer is required to satisfy themselves about it. It is a separate matter from metering, and it is covered in telling the network operator.

If you have solar as well

Here a smart meter stops being optional. To be paid for electricity you export, the supplier has to measure the export, and that means a meter capable of reporting half-hourly export readings. Without one there is no export payment, whatever the panels are producing.

A house with both solar and a heat pump has the strongest case of anyone for a meter that works properly, since the export payment and the heating tariff both depend on it reporting.

The use that comes before any of this

A smart meter fitted a few months before the heat pump gives you something worth having: several months of half-hourly data about your house as it is now.

That tells you the shape of your electricity use — when you are in, what the baseline load is overnight, how much of the day the house is empty. It is the same data that makes solar worth estimating properly, and it is a far better basis for a conversation with an installer than a recollection of what the house is normally like.

It will not tell you how much heat the house needs. That comes from a year of gas or oil, and a summer month to separate the hot water out, which is in reading your electricity bill.

If you would rather not have one

You can decline, and plenty of people do. Nothing about the installation, the certification or the grant changes.

What you give up is access to the heating tariffs, which means paying a single rate for every unit including the ones a heat pump could have bought at three in the morning. On a house using 6,000 units a year for heating, that difference is not small, and it repeats every winter. The running cost calculator will show you the size of that gap with your own figures, which is worth doing before you decide.