Technology
Heat pumps
Two different machines share this name. An air-to-water heat pump feeds radiators and hot water and heats only. An air-to-air heat pump is a reversible air conditioner and does both. They carry different grants and different rules, so this site never says heat pump without saying which.
The units
3 in the database, every figure copied from the manufacturer's own specification page with the date somebody read it. Nothing has been bought, run or measured, so there are no scores.
Air-to-air heat pump, reversible
- MSZ-AP25VGK with MUZ-AP25VG outdoor unit Mitsubishi Electric
- MSZ-AP35VGK with MUZ-AP35VG outdoor unit Mitsubishi Electric
- MSZ-AP50VGK with MUZ-AP50VG outdoor unit Mitsubishi Electric
Writing
-
What scrapping the gas standing charge does to the cost of heating
Your Home
Gas standing charges are going, and £108 a year moves onto the unit rate. Who gains, who pays more, and what it does to heat pumps and air conditioning.
David White -
The heating season is getting shorter, and by how much depends where you live
Your Home
Heating degree days computed from this site's own 1950 to 2026 series. Every one of 25 towns needs less heating than it did in the 1960s.
David White -
Your heat pump's efficiency more than halves in the cold, and the maker publishes the number
Your Home
Mitsubishi's own declared data for a unit in our database: efficiency of 7.0 at 12 degrees outside, 3.0 at minus 7, and 2.24 at the operating limit.
David White -
Air conditioning planning permission outside England
Choosing and fitting
Scotland, Wales and Northern Ireland each run their own regime. Scotland is strictest, and its condition is about what the unit is used for, not its size.
David White -
What should be in an air conditioning quote
Choosing and fitting
A quote with one number on it is not a quote. What the survey should have covered, how many units you actually need, and what to settle before signing.
David White -
Your air conditioner is also a heater, and this is the arithmetic
Your Home
Six of the nine air conditioners in our database heat as well as cool. Whether running one beats your boiler comes down to a single break-even number.
David White -
What the state pays towards a heat pump, and the catch on all of it
Choosing and fitting
£7,500 for air-to-water, £2,500 for air-to-air, £1,500 more if you are off the gas grid on oil or LPG. Every one of them runs through MCS.
David White -
What the October 2026 price cap changes about what you run
Your Home
Electricity loses its VAT and gas rises 8% from 1 October. The verified rates, and the point where a heat pump becomes cheaper than a gas boiler.
David White -
Fitting air conditioning in a flat, and why the lease decides
Choosing and fitting
In a flat the planning rules are the easy half. The lease, the freeholder and who owns the external wall decide whether a split system is possible.
David White -
Air conditioning now qualifies for a £2,500 government grant
Choosing and fitting
Air-to-air heat pumps joined the Boiler Upgrade Scheme on 28 April 2026. A cooling-only unit does not qualify, and neither does a non-MCS installer.
David White -
The planning rule that decides what air conditioning you can fit
Choosing and fitting
In England a unit that only cools is never permitted development, at any size, in any position. One that also heats often is. Most sites miss this.
David White