The number is the number

Usually not. Since May 2025 the rules in England are more generous than most sources still claim: the old one-metre-from-the-boundary rule has gone, the size limit rose to 1.5 cubic metres, and a detached house can have two units. What replaced it is a noise test — an MCS 020(a) sound calculation showing 37 dB or less at your neighbour's windows, which is stricter than the old limit and is now the only accepted route. We run that calculation at survey and give you the result in writing. Conservation areas, listed buildings, national parks and most central London boroughs are the exceptions, and we check yours before quoting. Scotland, Wales and Northern Ireland have their own rules.

Air-to-air heat pumps became eligible in April 2026 — £2,500, residential only. Not the £7,500 you will see quoted everywhere, which is the air-to-water figure and does not apply here. The EPC requirement was dropped in the same overhaul. It is only available where the property has no fossil fuel heating system, so if you have a gas boiler you are not eligible. We will tell you honestly whether you qualify rather than letting you find out later.

£95, refunded in full against the order. It funds a proper visit rather than a fifteen-minute look, and it means the person who arrives has time to work out where the unit should actually go and to run the noise calculation. If you go ahead, it costs you nothing.

A modern indoor unit runs at roughly 19–25 dB on low, which is quieter than a fridge. Owners describe it as almost silent when it is holding temperature. The outdoor unit is the one worth thinking about: typically 45–50 dB at one metre, and audible at start-up. Where it sits relative to your bedroom window and your neighbour's is part of what we design at survey — and since May 2026 it is also a legal requirement, calculated and evidenced.

In cooling, a 3.5kW unit draws roughly 0.8–1.1kW, so around 25p an hour at current rates. In heating it is three to four times more efficient than direct electric, which makes it substantially cheaper to run than panel heaters. Efficiency falls as it gets colder — below about −10°C outside you are closer to break-even with direct electric, and we would rather tell you that now than have you discover it in February.

That is the most common objection and it is worth answering properly. If you only ever run it in a July heatwave then yes, it is expensive per day of use. The reason to fit one is that the same unit heats: it will take the chill off a single room in October without firing the boiler for the whole house, and it reaches temperature in minutes rather than the hour a wet system needs. Most of the annual saving comes from the shoulder months, not the summer.