Aircon - Mobile unit for approx. £200 - any ideas?

I bought a Homebase one for £150 last year does me fine but clearly not as good as the 2 part ones as it doesn't recycle the air in the room but draws warm air from outside. Also when in full cooling mode rather than idling on the fan uses 1100watts so not cheap to run

I put a piece of thin ply in the open window with a hole cut out the size of the vent pipe worked well

Changed it later for a tumble drier vent kit fitted through wall worth the effort

I am using it in a 7 metre by 3 metre west facing room with patio doors

Most popular room in the house at the moment

Regards

Tony

Monobloc units of the type your describe are essentially useless. A search for air conditioning threads on uk.d-i-y on Google groups will tell you why.

(I have one - it's OK for cooling a room with little or no solar heat gain and no computers. My office, about 4m x 4m with 4 computers and 2 sq m of SW facing window, it cannot cope.)

Currently the outside shade temperature is 32 C but 24 C in the office with the unit it running on medium setting

The air temp at the front of the unit is 13.4 C so I am getting some cooling and a flow of cool air

Tony

The problem with these units is that whilst they shove cooled air out the front, they also throw out lots of heat from the rear and chuck your expensively cooled and then heated air out the pipe. They are an environmental disaster and should be banned.

Christian.

This last may be true but it's not "these units". All aircon works like this!

Not at all. Other types of air con units don't do this. Because:

(a) The back (condenser) is outdoors so can shove out as much parasitic heat as it likes without affecting the building. (b) The air actually heated by the condenser and released through the outlet comes from outside. Expensive interior cold air is not used for this purpose.

Basically, running a single pipe portable air conditioner causes as much baking hot air to come in from outside as it pumps outside through its hose. A split system actually provides no ventilation at all, so doesn't let hot air into the house. A sophisticated building system may be designed provide controlled heat recovery ventilation.

Some portable air con units can be modified by attaching an additional hose with duct tape to the inlet grille, so that outside air is used on the condensor. However, not all units can be so modified, as the supply for the evaporator (inside air that comes cold out of the fan) must be interior air, so this is only possible if the supply for each function comes from a different grille.

Christian.

Mine does not throw heat out of the rear only out of the pipe

And the alternative is?

I suppose I could get into my air conditioned car and drive to my air conditioned office rather than working at home

I guess I could also switch off my fridges freezers and water cooler as well as they appear to be chucking out loads of heat just to keep things cool

And who needs a computer heating up the office anyway

Just out of curiosity how much more environmentally friendly are proper air con systems? It may be better if I move up to one of those

But then again I am not sure of the environmental damage to the countries producing them

Tony

It does produce heat out of the rear, as the casing and pipe will be hot and poorly insulated.

Buy a split unit, not a portable.

Vastly more efficient. Even more so if your building is properly insulated and ventilated correctly.

Christian.

Yeh but no but...

You can overcomplicate these arguments. All aircon units consume electric power. This power is turned into heat and this heat is absorbed by the outside air, whatever the type of unit. Power stations with their carbon load are therefore being used to heat the atmosphere, again whatever the type of unit and some would regard differentiating betweend them (in terms of environmental impact) as nit-picking!

It is true that an insulated box with no ventilation, cooled by a split unit will need less power but most air conditioned areas have ventilation as well and ingress and egress of people, much reducing this efficiency.

Far better to design houses and clothing appropriately and get used to it. Hands up - I do enjoy being air conditioned at work but at home one sits in the shade, avoids exertion and drinks a lot of fluids.

Yes, but the efficient units are pumping out less heat and carbon dioxide. Probably by several times over.

The ventilation will be a tiny fraction of that provided by a portable unit's extractor. Of course, for air con to work efficiently you have to close the windows. However, hot weather is normally associated with calm winds, so natural ventilation will actually be quite low. Of course, insulation and reducing ventilation down to the minimum comfortable level (or better still providing plenty of heat recovery ventilation) is the way to go.

Indeed. However, I like to think of the entire picture. Whilst I am very interested in environmental affairs, I'm not some Greenpeace nut. Having everyone work at 50% efficiency because they are too hot is not environmentally friendly, in my book, as it wastes resources.

Christian.

A split portable unit will be about 20% better than one that uses a hose.

A split unit with the compressor outside is about 50% better but I have never seen a portable one.

I may replace my portable split unit with a heat pump to provide heating and cooling instead of the gas boiler.

They can be seen quite often, slung out the windows of offices. The outside part is a rectamgular unit with a couple of small fans in, and you can see a couple of hoses connected to them.

Mine is like that.. but the compressor is inside not outside. You can tell because the inside unit weighs about 30kg.

This means that the heat produced running the motor has to pass through the pipes carrying the heat extracted from the room. This makes it less efficent than having the compressor outside and cooled by external air.

Like I said I have never seen a portable one with the compressor outside.. they are too heavy for people to hang from windows, etc.

Actually, the compressors are all cooled primarily by the refrigerent carrying heat away from them to the condensor, and not directly from the casing even though it gets hot. (Same is true of fridges/freezers.) Compressors normally go outside because of their noise/vibration -- it makes no difference to the efficiency.

These guys seem to be managing OK...

Are there any domestic air-con units that do something constructive with all this waste heat ?

Presumably all this heat could be used for something useful like hot water or a swimming pool instead of going to waste ?

Its pretty low grade. but you could use it to preheat the water in a hotwater system, or a pool. If you want to be green you can put it into a ground storage system and extract it later when the weathers gone cold. All of which cost money.

We tried a big hose one about 10 years ago. It went back the next day.

We then got a split one(12000BTU), with a pair of hoses and a cable interconnecting. It's still going strong, attempting to keep most of the house cool, It's struggling, at around 22-24C but keeping the humidity down (and comfort up).

It cost about £1500 10 years ago, but similar ones are sub £500 now.

I wouldn't have thought it makes a difference where the compressor is (inside or outside). So long as the heat is carried outside, through insulated pipes, where a fan can waft it all away, then that's what counts.

-- JJ

Whatever you do will cost money. The trick is to know what you are going to pay, and make sure you can afford it. Can any of us say with any certainty, what a litre of petrol, or a kilowatt-hour of electricty is going to cost in ten years time?

-- JJ