How do you keep cool?

[jthjth]

Just realised, did you mean to write gas heating OR economy 7 rates? If so my post was made in error…

Looking back at my post my language wasn’t entirely clear. The air conditioner in heating mode, provided it is using Economy 7 electricity, works out to about half the cost of the equivalent amount of gas boiler provided heat..

== Doublepost prevention - post automatically merged: 27 Jun 2026 ==

This is a major downside to portable systems. If you move around a lot between homes or are a renter they are better than most solutions, but single-hose units have to pump the heat energy somewhere, and even when aimed outside that giant pipe will be giving off the heat that comes back into the room. They also use more electricity for less efficiency which is why I'm looking at split-system units.

Yes, the often overlooked issue with portable units is that you expel hot air through the hose out of the window. That air has to be replaced somehow, usually through the various air leaks in the house. That air is inevitably warm air.

A split system cools the same trapped volume of air, so it’s not continuously trying to cool warm outside air. Rather like having car air con on recirculate.

 

[Class 317]

The problem for us is getting the bedroom down to that temperature, for the past two nights the upstairs temperature hasn't dropped below 31, a good 8-10 degrees warmer than the overnight temperature outside.

We've decided to invest in a portable aircon unit for the bedroom, since the aim is to merely reduce the indoor temperature to the same level as outdoors, we're hoping the open window for the outlet hose won't be a problem.

Would highly recommend getting an insulated window cover with a hole for the tube and an insulated cover for the outflow tube as well.

Both have improved the cooling potential if the unit I have quite significantly.

 

[S101]

We had aircon fitted properly a few years ago, in the main bedroom, and downstairs. Best thing we've ever spent money on. Cheap to run too.

 

[martin2345uk]

We had aircon fitted properly a few years ago, in the main bedroom, and downstairs. Best thing we've ever spent money on. Cheap to run too.

We had it, just in the bedroom, and yes it's absolutely wonderful to have a cool room to retire to on the hottest days

 

[Bayum]

Hot water bottle…


Hear me out. Leave in the fridge/freezer and remove as needed. Great for bedtime as you can cuddle the cold water bottle in a towel.

 

[martin butler]

I have extra showers, then go infant of a fan in a towel, which is a doubly cooling effect.

Also before bed I've discovered applying Deep Freeze pain relief gel to my legs makes my whole body feel colder. This only lasts about 20-30 minutes though and shouldn't be done constantly.

Just be very careful where you might feel the need to scratch, afterwards

 

[Railwaycat]

It cost us £3k to have two indoor units (lounge and bedroom) and one outdoor unit, fitted last autumn. Between them, with the internal doors open the entire house sits at 22C. We also use them for heating overnight in the winter. About half the cost of gas heating on Economy 7 rates. Best £3k we’ve spent in ages.

Can you let tell me what system you got and who installed it please? We've just had 6kw of solar panels and an 11kw battery (thinking of adding another one for the off peak rate in winter) and most of the output is going to the grid, it's only when we use the shower (battery can only output just over 3kw at once) that we use any grid electricity at the moment.

 

[jthjth]

Can you let tell me what system you got and who installed it please? We've just had 6kw of solar panels and an 11kw battery (thinking of adding another one for the off peak rate in winter) and most of the output is going to the grid, it's only when we use the shower (battery can only output just over 3kw at once) that we use any grid electricity at the moment.

Installed by Leicester Aircon

Best Split Air Conditioner Unit | Cheap and Ducted Air Conditioning

Best Ducted air conditioning units keep your home cool. Discover the latest Split Unit Air Conditioner with Leicester Air Con. We also have a range of Cheap and Multi Split System Aircon.

www.leicesteraircon.co.uk

A Mitsubishi Heavy Industries system. (Confusingly there are two unrelated Mitsubishi companies making air con)
Downstairs has a 3.5 kW indoor unit
Upstairs has a 2.5 kW indoor unit
Outside there is a single outdoor unit

Great firm to deal with. A friend has just placed an order, quoted an August fitting date. I thought they might have had a much longer backlog.
As to your surplus going to the grid, I assume you are looking to get put on an export tariff? Octopus pay me 12p/kWhr.

 

[Railwaycat]

I'll have a look at that, thanks.
I shall be going with Octopus with the tariff, but it was only signed off last week so all the documentation has only just come through. I had the system from Glowgreen, very reasonable price (£8500) based in Bournemouth, but the installation was by a Mansfield company that I didn't get the name of - the installer did say that they were a solar package provider themselves so maybe I could have got it even cheaper. I was surprised when they simply set me up on the system before they went and I was generating!
Have you heard of Axle energy? I was talking to a builder who was also waiting for the Octopus tariff, and he said that through them you could get more than 12p (he did have 2 batteries though) but still be with Octopus - had a quick look but will have to ask a technical friend to explain it to me.

 

[jthjth]

I'll have a look at that, thanks.
I shall be going with Octopus with the tariff, but it was only signed off last week so all the documentation has only just come through. I had the system from Glowgreen, very reasonable price (£8500) based in Bournemouth, but the installation was by a Mansfield company that I didn't get the name of - the installer did say that they were a solar package provider themselves so maybe I could have got it even cheaper. I was surprised when they simply set me up on the system before they went and I was generating!
Have you heard of Axle energy? I was talking to a builder who was also waiting for the Octopus tariff, and he said that through them you could get more than 12p (he did have 2 batteries though) but still be with Octopus - had a quick look but will have to ask a technical friend to explain it to me.

I’ve looked at Axle energy and various smart Octopus tariffs. The thing is, you can start to become obsessed and start devoting a lot of brain power to save a few pennies. I prefer the certainty of knowing the fixed Economy 7 hours. In winter the battery is charged overnight and the aircon runs as a heater overnight.

 

[Snow1964]

It cost us £3k to have two indoor units (lounge and bedroom) and one outdoor unit, fitted last autumn. Between them, with the internal doors open the entire house sits at 22C. We also use them for heating overnight in the winter. About half the cost of gas heating on Economy 7 rates. Best £3k we’ve spent in ages.

Similar idea of lounge and bedroom, but we had wall unit in lounge, and a loft unit that ducts to 3 bedrooms linked to outside unit. In hot weather we shut the windows and curtains and run a/c

Can also use it for fairly quick heating top ups if we have been away and turned heating off/down. We have gas boiler and underfloor heating, great for even warmth, but no where near as quick as radiators from turned off.

Good Investment, if your home isn't comfortable all year then might be miserable or depressed

Next stage would be to look at getting battery unit in garage, as a/c tends to be run afternoon & evening whereas cheap electricity is midnight to 6am (we are on EV tariff).

 

[Harpo]

As I posted in another thread somewhere…..?

As well as the hot side (everything shut)/cold side (all open) stuff, my kitchen is on the hot side of the house so I use the extractor hood to pump air out on that side and increase the flow in from the cooler side. If you have a bathroom/toilet extractor on the hot or south side, it could do the same job.

A bowl or bag of ice by your inlet window can help too.

 

[Railwaycat]

The thing is, you can start to become obsessed and start devoting a lot of brain power to save a few pennies

I know, but in my case actually having to use my brain was very welcome!

 

[Essan]

I just go up to the Highlands for the week Slept no problem last week!

Sadly, won't be an option next time ...... And even portable air con is outside my budget. Probably sleep on the floor downstairs (and pretend I'm in a bothy!)

 

[nlogax]

Live in Scotland and it's almost a non-issue.

Early daytime deployment of curtains and blinds takes the edge off if it gets particularly warm, 'particularly warm' meaning high 20s which even then is a rarity.

 

[swt_passenger]

You know how YouTube bombards you with adverts for pocket sized air conditioning that runs off a USB port or similar, invariably invented by former NASA or ESA engineers working in their kitchen or garden shed?

I reported one of them as a scam just to see what happens, its claims being scientifically impossible, so you’ll be glad to know that it “Doesn’t go against Google policies”. So that’s ok then…

 

[Giugiaro]

Watering surfaces help dissipate accumulated eat in surfaces like walls, floor and roof. The water carries energy as it evaporates. The concept is similar to sweating in our bodies.

This is a common trope from Japan, and we use that to cool the roof of the Guifões workshops' cafeteria.

There was also the old "tropical roof" concept, where a second lining over the main roof would create a cushion of insulating air, which would also allows air to rob some energy, as the ends of the tropical roof were kept open for air to circulate through.

Then, using white painted walls, both inside and outside, is a technique used for centuries to prevent accumulation of excess solar energy. Even the Italians employ this methodology in their rails, and also why I bought my car in white.

 

[Harpo]

You know how YouTube bombards you with adverts for pocket sized air conditioning that runs off a USB port or similar, invariably invented by former NASA or ESA engineers working in their kitchen or garden shed?

I reported one of them as a scam just to see what happens, its claims being scientifically impossible, so you’ll be glad to know that it “Doesn’t go against Google policies”. So that’s ok then…

Funny enough my other half showed me one that caught her eye today as a ‘good idea’. It didn’t seem to need a hole in the wall or any other external vent to pump the heat away. An engineering miracle!