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A2A vs A2W: Which Heat Pump Would You Pick? Poll is created on Nov 24, 2025

Air-to-Water

Air-to-Air

Not sure

Neither. Sticking with my boiler

A2A vs A2W: Which Heat Pump Would You Pick?

Mars · 2025-11-24T22:55:47Z

It’s looking increasingly likely that air-to-air heat pumps (essentially AC units used for heating) may soon qualify for a £2,500 Boiler Upgrade Scheme grant. That means homeowners could soon have two subsidised options: Air-to-Water (ASHP) with the current £7,500 grant Air-to-Air (A2A) with a proposed £2,500 grant Each route has pros and cons: installation cost, comfort, efficiency, hot water, running costs, and complexity all differ. So the big question for homeowners is, if both were subsidised, which would you install: A2W or A2A?

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Air Source Heat Pumps (ASHPs)

Last Post by Anne Smith 4 hours ago

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Anne Smith

(@anne-smith)

New Member Member

Joined: 5 hours ago

Posts: 1

25/04/2026 6:29 pm

@temperature_gradient I've had air-to-air for just over 3 years and once you realize how best to use it, its great. Mine is a Mitsubishi with 2 2.5kW wall units, one in the kitchen/utility area and one in the main bedroom and a 3.5kW floor standing unit in the sitting room/dining area. I have a fairly standard 1970s 3 bed semi. I have also kept some of my original electric radiators, thinking I might need to use them if it got very cold. For the first 2 winters I tried to run the heating like a gas boiler, programming it to come on morning and night with a manual boost in between if I needed it. I was using the electric radiators during cheap rate at night (on Intelligent Octopus Go). I found the temperature of the house fluctuated enormously, heating up very quickly, but cooling down fast too. During the winter just gone I changed the strategy and got a very pleasant surprise. Instead of trying to heat each individual room, I used the 3.5kW heater in the living room to heat the whole house, with all the doors open and left it running 24/7. Once the ground floor had got up to temperature the system ran on 400-600W most of the time, only ramping up further if it was really cold outside. A surprising amount of heat made its way into the upstairs rooms. As the kitchen area is single storey with 3 outside walls, I also ran the unit in there for a few hours at night, and I sometimes had to put the bedroom unit on for 20 minutes or so before I went to bed. Other than that, on the coldest nights the 2 1kW radiators in the small bedrooms came on and I have an electric towel rail in the bathroom. The ability to switch to cooling in the summer is a real bonus.

Hot water is provided by a Sunamp thermal store, which can be charged with cheap rate electricity in winter and charges via a solar diverter in summer. This fits into the cupboard that used to house the combi boiler - no need for extra tanks.

There is one other bonus to air-to-air - a decent reduction in humidity. Before I got the system most of my rooms were above 60% all the time and the kitchen and bathroom were often in the 80%s. While I never actually got mouldy walls, I did find I had to run a dehumidifier a lot of the time to try to keep the humidity down. Now the whole house has settled into the 40s-50s and even if the kitchen or bathroom gets steamy it is easy to dry it out again, unlike before.

This post was modified 4 hours ago by Anne Smith

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