Why the timing of heating matters as much as the technology

Installing a heat pump is a big step, but the difference between a system that quietly saves you money and one that quietly drains your bank account often comes down to the controls. Heat pumps run at lower flow temperatures than boilers and take longer to warm a home, so they respond best to gentle, well-timed instructions rather than the on-off bursts we are used to. Get that timing right and you can heat the house during the hours when electricity is cheapest and lowest in carbon, then coast through the expensive peaks on the warmth already stored in the fabric of the building and the hot water cylinder.

That is the promise of smart controls, and it is a genuinely practical one. It is not about gadgetry for its own sake. It is about matching when you use energy to when the grid has plenty of clean electricity going spare, usually on windy and sunny afternoons.

What smart controls actually do

At their heart, most smart heating controls do a handful of useful things:

• They learn the building. After a week or two, they work out how long your home takes to warm up and cool down, so they can start heating earlier on cold mornings instead of guessing.
• They read the weather. Internet-connected controls pull in local forecasts and adjust flow temperatures ahead of a cold snap or a mild spell.
• They respond to price signals. Paired with a smart meter and a time-of-use tariff, they can shift heating and hot water into cheaper half-hourly windows.
• They coordinate with the grid. Some can take part in demand flexibility schemes, nudging consumption up or down by a degree or two when the network is under strain.
• They give you visibility. Good apps show you what the system is doing and why, which makes it much easier to spot a setting that is wasting money.

Get the foundations right first

No smart controller can rescue a system that has been badly set up. Before you start chasing clever scheduling, make sure the basics are in place.

Weather compensation is the single most important setting on most heat pumps. It adjusts the flow temperature continuously based on the outdoor temperature, so the pump runs cooler and more efficiently on mild days and only works harder when it truly needs to. If your flow temperature is pinned at a fixed high value, you are paying for it every hour of the heating season.

Balanced radiators and good insulation matter too. A heat pump wants to run long and low, and that only works if heat can get out of the emitters easily. If one room is always cold, resist the urge to turn the flow temperature up. Fix the radiator sizing or the balancing instead.

A sensible setback schedule is the third pillar. Dropping the temperature by two or three degrees overnight and when the house is empty works well with a heat pump, provided you allow enough recovery time in the morning. Deep setbacks of five degrees or more usually cost you more than they save, because the pump has to work hard to catch up.

Tariffs, pre-heating and thermal storage

This is where smart controls earn their keep. If you are on a time-of-use tariff, electricity is typically cheapest overnight and in the middle of the day, and most expensive during the early evening peak. Your heat pump can take advantage of that in two ways.

First, pre-heating: rather than waiting until the house feels chilly at six in the evening, the controls warm the building gently during the cheap afternoon window, then let it drift down through the peak. The building itself becomes a battery, holding warmth in its walls, floors and furniture.

Second, hot water scheduling. A well-insulated cylinder is an excellent thermal store. Heating it during cheap, low-carbon hours and then drawing on it later is simple, effective and needs no new hardware beyond a cylinder thermostat your controls can talk to. If you have a larger cylinder, you can often store enough hot water for a full day of showers in one cheap window.

Do check that your tariff actually suits your pattern of use, though. A tariff with a very expensive peak only pays off if you can genuinely avoid that peak.

Easing pressure on local networks

There is a wider benefit here, and it is one worth understanding. Local electricity networks were largely built for a world without heat pumps or electric cars, and the cables and substations on your street have limits. When hundreds of homes all draw power at once on a freezing evening, that local network feels the strain, and reinforcing it is slow and expensive.

Smart controls help by spreading the load. Shifting a few kilowatt-hours of heating into the afternoon, or briefly pausing a hot water cycle during a peak, reduces the maximum demand a street places on the grid. In aggregate, thousands of homes doing this could defer significant network upgrades, which keeps costs down for everyone and allows more heat pumps to be connected without waiting.

Practical steps to take now

• Check your flow temperature and weather compensation curve before changing anything else.
• Ask your installer to show you how to adjust the heating curve yourself, and write down the current settings.
• Add a hot water schedule that uses your cheapest hours, and keep the cylinder well insulated.
• Set an overnight setback of two to three degrees rather than a deep one.
• If you have a smart meter, look at your half-hourly usage for a week to see where the peaks really are.
• Review your tariff alongside your controls; the two need to work together.

None of this requires heroics. A few thoughtful settings, reviewed once a season, will keep your home comfortable, your bills lower and your local network a little happier.