I think I understand that proper air conditioning needs an external and internal unit so that heat/moisture can be dumped outside.
Is there any from of portable unit that works on a standalone basis? I would want to cool just one room so that I can sleep in a cool room when the weather is exceptionally hot/humid. Happy to empty a condensate drawer regularly.
Many thanks.
Portable units work great, but there are two distinct issues:
I'd also add in that you need to do some maintenance as well. Regularly draining it, spraying the radiator fins with a weak bleach solution (otherwise your exhaust can smell really awful). The heat really doesn't help the exhaust pipe fittings, either. I bought a sturdy Prem-i-air unit about a decade ago that was meant for hire shops, but the plastics for the hose fittings have become brittle over time.
So if you don't mind something noisy and you can do a semi decent seal around the exhaust pipe you'll be golden!
So you wish to defeat the laws of thermodynamics
There are portable "monoblock" air con units. These typically have a hose that you direct out of a window (ideally with some baffling round so that you don't leave the window in effect open).
They work, but do have a number of limitations. Firstly (and most importantly for a bedroom), is they are noisy since you get the noise of the compressor, high throughput fans in the one box. The are also somewhat inefficient since most of them work by drawing in air from the room, some of which is cooled, dehumidified, and recirculated, but some is also expelled to the outside to vent the unwanted heat. That then means that you create a pressure drop in the room which will draw warm moist air in from elsewhere.
You may be able to find some which are dual hose - these are better since they recirculate the the room air, but draw the air into which the excess heat will be dumped from outside.
I've just bought one of these:
It replaced my 20-years old unit which no longer cooled. I was very surprised how much quieter it was, particularly on the slower of the two fan speeds. Even at that setting, with it 28°C outside, it had no problem keeping the 25m^2 lounge cooled to 22°C. I vent the heat to the outside via the supplied ducting fixed into a 4 x 2 piece of 4mm dual-wall polycarbonate. That rests on the side-opening casement window space, and is held in place with several pieces of Velcro round the edge. At night it is easy to remove and I can close and lock the window.
In a bedroom it should be easy to keep the temperature down on the lower fan speed. The problem would be venting the warm air to the outside if you're on the ground floor. You could probably find a way of using 10mm twin-wall polycarbonate for a side-opening casement window and locking that in place for partial security, as 4mm isn't strong enough. Other than that, you'd have to put the hose through a top-opening casement, and it would be barely long enough with the a/c unit right against the wall under the window.
As to noise, earplugs would help if you're particularly sensitive. In any case, you might get used to the noise, but you won't get used to the heat if you haven't got an a/c unit!
In theory, an evaporative cooler can work, but they only work when the humidity is very low, so no use on that soggy island.
I would prefer this kind of portable, if it was available. There are zero of these in local retail stores.
There is a sea of single hose units, and only a few of these.
This is "like a window air conditioner" except it does not sit in a window. And the air path to the out-of-doors is implemented with hoses (inlet hose, exhaust hose). The inlet hose and exhaust hose are the "hot air path". They're not intended to admit fresh air to the house.
If you buy a 10,000 BTU unit and put it at the other end of the house, you can bring the house temperature down a bit, and still get a nights sleep in your bedroom at the other end of the house. The bedroom still won't be all that cool, but it is a "better than nothing" solution until you fit your splits. I have a box fan and a slightly smaller fan, for moving air from the "refrigerated room" to the rest of the house. But the airflow does not reach the bedroom -- if it did, the noise level would be too high.
Paul
I'm not sure if the explanation for the advantages of a dual-hose unit makes complete sense, and they don't seem to be available in the UK anyway. Sure, the single-hose creates a negative pressure and draws warm air in from outside, but that air is diffuse, coming in through cracks around the door. Now that air will already be in the house, and so at the temperature of the house, which unless something strange is going on, will be lower by several degrees than the outside temperature. The a/c unit will therefore be cooling "house" air which might be at 25 °C rather than "outside" air at 32°C, and pushing out cooled air into the room at 22°C. The exhaust duct air to the outside will be a lot hotter, perhaps 50°C or even more (I haven't measured it).
Now take the dual-hose unit. It's taking in air from the outside at 32°C and using that to "cool" the compressor coils which then produce the
22°C air for the room. The exhaust temperature will be at least as high as the single-hose unit, as it's using 32°C air rather than 25 °C air. So in effect it's always cooling air which is several degrees higher than the single-hose unit. Wouldn't that make it more expensive to run?Well, I suppose that as this is a DIY group,it might be possible to try this one day:
My old a/c unit certainly had to be emptied of condensate (why are they always right at the bottom?!), but according to the instructions, my new a/c uses the hot part of the heat exchanger to evaporate the "condensate" and take it out of the exhaust hose. It's only in high humidity conditions that more condensate that that system can deal with with be produced, and the tray require emptying.
I am the OP and following the replies carefully!
The air inside my house in summer is always 2 - 5 degrees hotter than the outside air.
Always? That's odd.
Overnight the outside air cools down, but the inside air won't cool down as much. So, perhaps by 7am, it might be 23 or 24°C inside, but perhaps only 16 or 17°C outside. Then, at the very least, you can passively cool the house by opening the windows to at least partially equalise the inside/outside temperatures. On a very sunny day, by mid-morning, the temperature outside will start to exceed that inside. It's then time to close the windows and any curtains/blinds you have on the east and south sides, adding the west ones after 2 pm. Depending on how much heat you can put up with inside will govern the time you turn on the a/c unit. However, by 7 or 8 pm, it's likely the inside and outside temperatures will again equalise, so it might be possible to turn off the a/c unit.
Anyway, if the temperature inside is always hotter than outside, and you have a single-hose a/c unit, that will be drawing the cooler air in from outside due to the negative pressure created by expelling the hot air. So it's a win-win situation!
Yes, we've been doing that for a number of years. Basically what people in hot countries do, though they usually have exterior shutters.
It's amazing how many people have all their windows open in the hottest part of the day...
So you're pulling 'house' air into the air conditioned room. But that makes negative pressure in the house, and how does that negative pressure resolve itself? Unless you are super airtight, the only way is that outside air is drawn into the house. Whichever way you do it, it involves taking warm outside air and bringing it in, which is counter to the idea of trying to keep things cool.
By running the thing constantly, effectively you're going to run out of cool 'house' air and the house will be brought up to the outside temperature (apart from air which can be cooled by contact with cooler surfaces like masonry). Eventually those cooler surfaces will warm up too.
The dual-hose unit keeps the 'house' air cool by not pumping it out the window: it's like a fridge where you have separate inside and outside compartments with no air exchange.
I 3D printed one of these:
Theo
And the air that replaces that will be coming from?
That is not always the case - when you add in the extra humidity and contribution of other energy contributors, the house will often be hotter/wetter.
Probably not - since you can keep the house better air sealed, so you are not always drawing more warm wet air in.
ISTR someone on this group has done that in the past - their monoblock aircon had identifiable separate grills where the room and and compressor cooling air were drawn in, so shuttering one with some cardboard and an extra hose was fairly easy.
I used to attach a hose to mine, and take it out of the window with the hose. (the unit sat on a waist level bookshelf - so the run was all down to the window)
Gravity!
Many fridges do much the same...
Why ?. Always keep windows and curtains closed on south facing walls when it is hot. If you have a conservatory on a south facing wall, get rid of it, unless you value the winter solar gain more than keeping cool in summer.
Stop the sun from hitting south facing walls/windows by planting suitable deciduous trees and shrubs.
Open windows on north facing walls for ventilation.
Make sure you have cavity wall insulation and 300mm of loft insulation to keep heat out in summer.
In Spain you could get a device which was supposed to cool air. You filled it with cold water and it blew air across it. Trouble was everything tended to get covered in condensation, so you then probably needed a de humidifier, but of course eventually the water got warm and you had to start again. I suspect that to do it properly would need an outside unit and a refrigerant connecting the units. I have seen some with a long pipe as well, but never tried one, as it seems daft to open a window and try to move hot air out when its hot there in the first place. Brian
I don't disagree with the theory, and you can't beat the laws of thermodynamics. However, the cooler surfaces will warm up, but the thermal mass of the walls will mean that the hot air drawn inside will, for some time, be cooled by those walls. Remember too that we are interested in cooling only one room at a time, so what happens in the rest of the house is less important (until you change rooms). The unit will not run constantly anyway; as soon as it reaches the set temperature it will stop or change to fan only. In the past, without a/c, when it's 30°C+ outside it never seems to exceed 28°C in the house. If that 28°C temperature is typical of the air used to cool the coils, surely the a/c is going to use less energy than if it used the 30°C+ air outside to cool the same coils. There is no doubt that eventually the warm air pulled in from outside would mean the room being "cooled" would reach the same temperature as that outside, but how long would that take? And that's a fairly critical point when comparing costs and efficiencies.
All I can tell you is that the temperature of the cooled air from the a/c is usually less than 10 °C, so it must be fairly efficient.
It will only be resolved by measuring total energy consumption over time under the same conditions (same a/c unit with insulated hose/s). I assume there are figures somewhere on the web, but I haven't yet found them. If dual hose a/c units are so efficient, why haven't they found their way to the UK yet? You can get imported 115V units, but then you've got to ad the cost of a pretty big autotransformer.
I can't argue with that analogy! I guess, though that it somewhat depends on how often you open the fridge door as to what sort of cooling unit would best balance cost and efficiency.
The exhaust hose on my old a/c unit was only 100mm in diameter, and very made of very thin polythene (probably less than 50 microns). I insulated it with a double layer of 10mm bubble polythene sheet. The new a/c has a much thicker polythene hose which doesn't get anywhere near as hot as the old one did. But I might insulate it if the temperature outside gets to 32°C, and the a/c has to work harder to keep the room cool.
That 3D-printed cover looks really good. The problem with my new unit is that all the LH side and all the back (with the exception of the outlet vent) is the air input. I'd have to check which is the room air input (which is then cooled and returned to the room) and which is the room air "cooling air" input which is then vented to the outside after it's been heated by the coils.
swamp cooler, works best where it's hot and dry ...
The single-hose arrangement seems to have the disadvantage that it is sucking expensively-cooled air out of the room.
With separate air circuits, all of the cooled air from the condenser can stay in the room. With only a single exhaust, some of the cool air from the condenser is going straight into the evaporator and going back outside, so the system must work harder to make more cooled air. I suspect that would negate any advantage from having cooler air over the evaporator.
nib
The control centre where I worked nore than 20 years ago had air conditioning but some shifts didn't like it, or believe it could be effective, so as soon as the sun came out they opened all the doors and the room temperature was raised not only by the external heat but also that from the adjoining equipment room and the several PCs housed in each console. When I was on, the doors were closed and the air con was allowed to work. When the night shift arrived, door openers, there was often a comment made about how cool it was. But it didn't stop them leaving the doors open when they were on duty on hot days.
See my reply to Theo.
I doubt it. Even a large TV and a few wall warts will probably amount to no more than 70W, probably contributing to less than 500Wh consumed in an average 24-hour period. As I mentioned in my reply to Theo, I've never seen the room warmer than the outside temperature on a summer's day.
The a/c unit will, of course, remove water by acting as a dehumidifier, and so make the air more comfortable. I've yet to get my head round the much cheaper evaporative coolers which, while cooling the air, increase the local humidity.
I think The Management would object to the appearance. Perhaps it would help if The Management was made to pay the electricity bill! ;-)
Well, yes, but why /right/ at the bottom? Can't they be a couple of cm higher?
Don't they all do that these days?
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