I need a portable A/C unit - modest size, modest capacity. In Homebase I saw what looks like a suitable unit - nice and compact. (Was going to post the URL but it is so long as to be silly.)
Listed as "9K BTU Silver Air Conditioner Unit" - I think it is an Amcor (in fact,I think it might be this exact model ).
Any comments on the manufacturer or, hopefully, the specific model? Or would you suggest alternatives?
They're not quiet, and they don't work very well because they draw the cooled air from the room to cool the condensor (hot element), and that air is replaced with the hot humid air from outside. So the unit wastes much energy fighting itself.
You really need a split unit, or a unit which keeps the evaporator (cold element) inside air completely isolated from the condensor (hot element) outside air flow.
Another minus point is that the collapsible elephant's trunk exhaust hose gets very hot and leaks heat back into the room.
They are so bad that for the last 2+ summers the secretaries have not bothered to use the one we have had one in our small office because on top of everything else, the exhaust hose requires the window open a few inches and traffic noise and warm air comes in, and the unit itself is just plain noisy.
9,000 BTU is just over 2.5kW not a lot when it comes to cooling. A non-active person chucks out over 500W of heat, solar gain through a sun lit window could easily approach 1kW/m^2.
Do really need cooling of the room or is what you want is to feel comfortable? For the latter you'd be much better of with a large slow fan or better a ceiling fan. A ceiling fan at low speed is virtualy silent and really does make a difference by very gently moving the all of the air in a room rather than a little jet of it like you get from a small fan.
I disagree. Many times when I was back packing round the Far East, Thailand, Singapore, Bali the ceiling fan really made a difference to room comfort. This is with humidity levels pretty high, so high that without the air movement from the fan your T shirt gets soaked and being inside really is unbearable, rather than just a little uncomfortable like the worst you get in this country.
Also being virtually silent you could leave it on at night, unlike the few times I had a room with aircon. Even during the day I would chose to use the fan rather than the aircon, just better all round.
2000Kcal per day in gives about 93W output with all energy going to waste heat assumed. I can't see where you'd get an average output of
500W from, unless maybe you're half plant & need photosynthesis taken into account too :)
When you are doing aircon calcs, 50W per body is a tyical assumption for office-type activities. During periods of higher activity, it's going to go up, but that's more likely to happen outdoors (or in a gym). The body can change it's heat dissipations dramatically though, and does so in order to regulate core temperature.
It was late after a long working day... Thinking about it now a person can generate, through physical effort, about 500W but they can't keep it up for long. 50W sat still as lost heat is much more resonable.
I doubt many could get up to that!, remember that demo in the science museum where you turn a handle to light a 30 watt light bulb?, takes some doing and I don't reckon many would do it for long!...
I recall timing myself belting up the stairs 3 or 4 steps at a time, and calculating around a kW. That's over a horsepower, although a horse can do that all day, and I can do it for 1 or
2 seconds max. On an excersise bike, in non-ideal conditions (warm day, dressed in a suit, no breeze), I could generate 250W for a minute or so (and probably longer if I was in shorts with a fan blowing at me). I've heard it said that a human-power, the amount of energy you can generate all day at a steady rate, is
80W. I assume this is for a moderately fit person.
A single arm isn't as powerful as two legs... Anybody reasonably fit ought to be able to generate 500W for a few seconds, with a proper warm up, burst and wind down. Though I agree many people may well not be able to get past the warm up stage...
In the past I would have been quite happy with a ceiling fan. In Sri Lanka I hated finding A/C. But in the Gulf it was just too hot for me to carry on like that.
Now circumstances here in England dictate that I have to do something to cool down the bedroom in the summer. Illness makes some other choices difficult or impossible. By getting a portable unit, partner might be able to have some benefit during the hottest days. (At work I can dive into the one room with A/C - the computer room.) Anyway, a split unit would be a problem due to lack of suitable locations for the exterior unit given geography, noise, and other considerations.
The unit I looked at has a quoted noise level of 54 dB which is the quietest that Homebase stock. I have always found it difficult to convert a figure in dB into a 'how loud that is' feeling. Sure, that is way more than a Daikin split unit.
Start by not letting it heat up in the day, keep the window(s) closed and the curtains drawn.
I suspect that this is something that you get what you pay for. I'd be reluctant to buy one from a shed. I'd want a real one not a cheap one, good balance of the moving parts is important.
And the walls will suck in more, and are larger. Shading of both helps.
But if the humidity is high it makes little difference. My aircon (soon to be replaced) is undersized, and barely drops the temperature, but the increase in comfort, as it removes a gallon of moisture per hour from the air, is enourmous.
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