Answering your Home Air Conditioning Questions (UK) 

I just had a full dual head mini-split air conditioning system installed, and last week I posted a video explaining what I’ve learned from having it for a couple months. I got a whole bunch of questions about the process, the units and lots more, so I figured I’d make a bit of an FAQ’s video answering your questions. I’m sure I’ll miss some, so if I do please do leave them in the comments! Right, let’s dive straight in with the most asked question, “Who did I use”?

The shortest possible answer I can give is that I used Checkatrade to solicit four quotes. All four quotes were about the same price – three came for free site visits before quoting while one just asked for pictures and measurements, then gave me a price then and there. Most of these installers are fairly local, and all offer a pretty similar range of units, and all for pretty similar prices. I went with the ones I did mostly because they seemed like good lads and if I’m being totally honest they said if I paid cash they’d give me the nicer Breezeless indoor units for the same price as the basic Midea ones, and that’s fine with me. Using a service like Checkatrade is genuinely the easiest way to do it, and you should get answers fairly quickly. That’s what I’d recommend.

As for pricing, I had quite the range of notes on that. Some were flabbergasted that it cost as much as it did, while others (mostly Americans it seems) were shocked it wasn’t £26,000. I paid £2,600, all in. The units themselves cost somewhere around a grand to a grand and a half, which means the labour cost eats up the rest. That’s two guys putting in an eight hour day of decently hard graft, and if they are somewhere around £80 an hour that about makes it up. As mentioned in the original video, that is an order of magnitude more expensive than a portable unit, but that’s also the going rate for a proper mini split that’ll last you at least a decade and work so, so much better. 

I was also asked about the DIY mini split options from the likes of electriq – often labelled “Easy-Fit” – which use R290 refrigerant (similar to propane) instead of R32 which is a ‘proper’ F-Gas, and requires F-Gas certification to work with, whereas R290 doesn’t. You can install an R290 AC system. At least before the heat waves, these sorts of dual head mini split systems were about £1000, which sounds like quite the hefty savings! Except after seeing all the work it took to install this system – which is functionally identical to the R290 ones – I’m really glad I just paid the guys instead. Boring a 40mm hole through my walls took them half the day – and they had a nice diamond tipped hole saw – plus you’ll likely still need a vacuum pump, and might need to top up the system, so this isn’t for the faint of heart. You can, for sure, but it’s a lot of work, and that still doesn’t cover stuff like the ducting outside, the insulation on the cold-side piping, or the knowledge to wire them properly. 

I also got some questions, pointed remarks, jokes and outright conspiracy theories about needing a license to get AC installed. The funny thing is I know where the kernel of truth in these extremely overblown stories come from. One guy posted on Reddit about how his local council was making him remove his AC because he lives in an ex council house, his neighbour complained and now he needs retroactive planning permission. The truth is actually pretty simple. Since May of last year (2025) air conditioning heat pumps fall under what’s known as “Permitted Development” – basically you can do what you like without getting planning permission or notifying anyone. There are a few conditions, namely the unit must be reversible – i.e. can heat AND cool – and can’t be a nuisance to your neighbours especially in terms of noise, but that’s pretty much it. I didn’t have to get permission to install this, and even if I did, there’s actually two kinds of planning permission, proactive and retroactive. You can apply before installing, or after. While the latter is technically riskier, it’s a common thing to think something is permitted development, be informed it’s not, then apply for planning permission, and more often than not it’s granted. See Colin Furze’s underground stuff for an example of that. Also, there is no big-bad government agency dedicated to seizing stuff here in the UK. There is no FBI that will come and raid your house. The police couldn’t care less. It’s your local council, and while it’d be a pain to deal with, no one is seizing your air conditioning. That doesn’t happen here. 

And actually while I’m on my highest horse, I got a whole bunch of hilariously smug comments from Americans saying “Welcome to the 20th/21st century!” or “it’s so weird you don’t have basic necessities like AC, the UK is so backwards”. You have to understand that these 40°C+ temperatures we are experiencing – literally death valley temperatures – only started in the last five years. Britain has been a frozen, rainy isle for centuries, and only through us boiling the planet alive has it become hotter than the temperatures we used to need to go on holiday to the south of France or Spain to experience. No shit we don’t have AC! My house was built some time in the 1880’s and has a fireplace in every room of the house, because adding heat was the only concern back then. Now we’ve trapped so much heat in the planet that we need to get some heat out the house. Our houses were built with central heating in mind (I mean mine wasn’t but it’s easy enough to retrofit), not central air. It’d be like you being surprised Alaska doesn’t have good AC. It’s ignorant and idiotic. 

Anyway, back to my system. A few people asked for more information on the installation, servicing and wiring, so let me explain that. The two guys drilled a 40mm hole in each room where an indoor unit is mounted, and attached the mounting bracket to the inside wall. They ran the trunking, mounted the outdoor unit, and wired the indoor units to the outdoor one. This is the important part. The indoor units are powered from the outdoor one. They don’t need power in the room they are in. They run a I think a four core cable from each indoor unit out to the outdoor one, following the refrigerant lines in the trunking, with two wires for power, and two for communication. The indoor units are what controls the outdoor unit – they command the compressor on, control the speed it runs at, and all the outdoor unit does is provide them power. They don’t need anything else other than a bracket mounting and one hole in the wall. I also simplified the gassing step in the video so let me expand on that here too. The lines they fit are obviously at atmospheric pressure when they install them (which involves soldering them together, flaring the nut ends and then screwing the nuts on), as is the indoor unit’s condenser (radiator), so they first pull a vacuum to draw out all the air and moisture. Then they fill the system with nitrogen and check for leaks, leaving that for some time to ensure it doesn’t drop pressure, then they vacuum the nitrogen back out and open the valve to the compressor which is pre-filled with the refrigerant gas. The amount of gas pre-filled in the compressor is good for I think 12 metre runs in my unit, although they will attach a bottle of the same refrigerant and top it up if needed. When it comes time for the annual service – a requirement for the 10 year warranty, and is somewhere around £100 a year – they will clean the filters, check the pressure and top up if needed, and ensure the system is running as expected. 

Lastly I do want to add some more about portable units, especially because last week the DIYUK subreddit was awash with debate around using the stock single hose, or modding your portable unit to make it a “dual hose” style instead. One nutter even used four hoses! The idea behind that is pretty simple. The main problem with portable units is they have to draw ‘cooled’ air from the room and pump it outside in order to cool the hot side of the system, which creates negative pressure in the room and means hot air from outside and around your house is drawn in to replace the evacuated air. By wrapping your portable unit’s hot side intakes in cardboard and attaching a second hose, you use the hot outside air to cool the hot side, leaving your cooled inside air alone. This is really clever, brings a big efficiency bonus, and should help the compressor live longer, but that does still leave you with a very noisy and physically very hot box in a single room drawing more power than my entire dual-room system draws. Of course if a portable unit is all you can get right now, absolutely, dual hose that bad boy and reap the benefits. I’m still incredibly glad I splashed out for the proper kit though.

I think that’ll do for now. As I said at the start, if I missed any questions please do leave them in the comments below!