How do portable units expel the heat?
Most units I have used in the past either have a heat exchanger (and fan)
mounted outside, or require a vent pipe for warm air to be blown out, so how
does a portable unit which says keep doors and windows closed expel the
Errr No ;-)
The portable units have a large flexible vent pipe like a tumble dryer -
you poke this out a window or through a vent as Andrew says below. If
you use a window then you want to open it only enough to accommodate the
end of the vent pipe and then preferably "fill in" the rest of the gap
(use a towel or wrap the curtains round the gap etc - some units even
come with foam batts designed for the purpose)
They will condense lots of water out of the air as well - most have an
internal reservoir that needs emptying from time to time. Some you can
connect a hose to if you can find a way to have the water run down hill
to a suitable exit.
On Sun, 10 Aug 2003 21:23:15 +0100, Dave Gibson wrote:
Some cheap "air con" units do use this effect and yes they do produce
a stream of cool air but as you say the humidity rises. After a few
hours your in cool sauna... and your own perspiration can't evaporate
either so it becomes really uncomfortable.
Anyway AFAICT the OP is referring to a proper aircon unit as the
features specifically mentions dehumidfication of the air, some thing
that only happens with a proper chiller unit.
Still need to dump the waste heat somewhere though. Depending on the
window design a board with a suitably sized hole would do, but really
only works on a sliding type window rather than an opening vent.
Dave. pam is missing e-mail
On Sun, 10 Aug 2003 18:33:08 +0000 (UTC), "Martin"
I've got one roughly the same size as the one linked by the OP.
If you recirculate the air, forget it - it'll add to the heat in the
room. Opening a window and dropping the exhaust pipe out can help, but
it doesn't really help much because more warm air comes in the window.
The only solution is a firking great 4in hole thru the outer skin of
the house, thru which you poke the exhaust pipe.
But a 12x12 room? No chance. I've got 2 PCs in my study, combined they
chuck out about 500w of heat. The mobile aircon just about keeps up,
but only just. If I go sit in the study to admire the slightly lower
temperature it's over the top. And my study is something like 6x9.
Basically these mobile units are a pile of pooh. Don't bother is my
suggestion. I understand from comments made by others that you really
need a dual unit, where the fan is inside and the heat exchanger is
outside (I hope I remembered that right). Expect to pay a grand or
more for something like that.
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That doesn't help -- the air still has to come back in from outside.
That's why such units are not as good as two part or fitted units.
Someone gave me one, claiming it not to work, which was for exactly
this reason. I doctored it to add a second hose which draws air in
which is passed across the condensor and expelled again -- this one
fortunately had quite separate air intakes for the condensor from
that for the evaporator which enabled me to keep the inside and
outside air paths isolated. That fixed the problem, but I've never
seen one which comes with two hoses for this purpose.
Mine's in a 10' x 12' room with computer and TV, but they probably
only total about 200W, and having hacked it, it works quite well.
It seems the performance must vary a fair bit depending on the unit....
I have seen powers ranging from 4000 btu/hour to over 14000 for
I use a 8000 btu/h in my office (approx 12'x10'x7'6"). With only 2 PCs
on, and me in it, the temp is currently 25.6c. The room next door is
currently 32c. It much less humid in here as well.
I would go along with the recommendation for a split unit, although I
would not be quiet as disparaging about the monoblocks if you get one
with enough power and can put up with the noise (i.e. probably not ideal
for the bed room!) Expect to pay 350 quid or more for a decent one though.
I have one of these from comet - i got it last summer, its a 8000 BTU
unit and it drops the temp of my bedroom (4M x 4M) by about 10
degrees. I agree about the vent pipe - you can either use the foam
rubber sheet they supply you with but with hinged windows (as against
sliding windows) you still end up with huge gaps to let in the hot air
and as you the alterntive is a 4" hold through the wall........BUT in
a true diy fashion i built myself a window wedge from scrap wood that
fits in the opening of the window when its about 1/3 open with a hole
for the vent pipe and sealed round the edges with pipe insulation. So
not i just need to open the window to it fullest extend, then shut it
on the wedge and insert the vent pipe - it makes a good seal all round
including top and bottom.......it works great....only problem is it is
a bit on the large size but still it works
As others have said the water filled ones aren't much cop (although some can
be filled with ice) and the portable proper ones don't have much power. A
friend of mine has one and it's about 500W or less of cooling. If you think
about how much energy it takes to heat a room up then it needs the same sort
of power to cool it down. And he has problems sealing around the exhaust
pipe (uses towel stuffed around the window).
Get a split unit, where the compressor sits outside. Don't waste your money
on cheap portables.
I installed one of these a couple of months ago.
Even with todays extream heat, I had to turn the thing down as it was
getting too cold indoors.
It seems the portable units aren't gaining favourable reviews. I'm not
keen on having a large floor standing unit on taking up space.
Having spent 5 years in the Middle East, I'm used to full house ACs -
a luxury I know!.
I'm keen on the split ACs. The wall units are not as obtrsusive and I
have a good place to put the condeser in.
A question about the external condensors - are they supposed to be
screwed into the floor/roof? I'm planning on placing it on a flat roof
so I can't screw it down.
Mine just sits on the patio. I haven't bothered to bolt it down. It's very
heavy; you may need a small crane or something to get it up to a roof. Also
consider the noise they produce, as it may upset the neighbours.
They're heavy, but I've seen them blown over on roofs.
If it is significantly taller than its width or depth,
you want to at least fix it to something with a larger
footprint, which also spreads the weight and might help
prevent damage to the roof covering. It's best to fix
them down if you can. Also think of the vibration
coming through the roof -- wouldn't be a good idea if
there's a bedroom underneath for example.
firstname.lastname@example.org (Andrew Gabriel) wrote in message
There is a dining room under the flat roof - which isn't used a huge
amount. Wonder if the vibration would cause any cracking on the
In terms of noise - I'm figuring there aren't any noise control laws
that would stop me using these? We are in a terraced house and the
neighbours bedroom window would be about 10ft away (approx. same
level) from where I plan to place the condensor unit.
My main worry (and the reason I asked about fixing the unit) is
someone nicking the condensor. The unit would be easily visible from
the street - our house is second one in from the street. Do these
things get stolen?!
One of the replies in this thread mentioed globalcooling.org.uk. Would
be interested in hearing on your experience once the AC has been
installed at your place.
No, just a hum. Imagine your fridge with a compressor some 10
times the power.
I would say that's far too close, given their window is likely
to be wide open and possibly trying to sleep in there when your
AC is running. Also, they might pick up a large amount of the
hot air on occasion.
Not often -- they aren't really any use by themselves.
We did have one taken from someplace I worked a long time ago,
but we were told that was rather unusual.
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