Do portable air conditioners work?

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Re: Do portable air conditioners work?

Postby Quokka2 » Sun Mar 03, 2013 12:16 pm

Privatteer wrote:...keeps a 6x6m room at 20deg on the really bad days ie 40deg


The one we bought didn't have any evaporative mode - maybe that is what's giving you more benefit in the dry heat. If it's only got one duct, it's still pulling 77L/sec of 40deg air into your house, changing the air in your room every 20 minutes or so and providing 1800W of heating. :?
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Re: Do portable air conditioners work?

Postby IrishPete » Mon Sep 29, 2014 11:08 am

Bit confused about the rude comments about Julia Gillard's home insulation program, as it was under Kevin Rudd. Sensible people widely regard it as potentially effective on a number of fronts:

1) economic stimulus to mitigate the effects of the Global Financial Crisis (something worked, because Australia got through that fairly unscathed; debt was the inevitable hangover, it was either going to be debt of recession/depression - I gather the current government would have preferred the latter);
2) reduced greenhouse gas emissions (through reduced energy needed for heating and cooling); and
3) reduced costs for the householder.
But badly implemented in a rush so that greedy and shoddy cowboy installers managed to ruin it for everyone.

Yes it is on topic, because it was an energy reduction initiative.

Back entirely on topic, I did not manage to get in on the gravy train, but did replace my corrugated iron roof a few years later and had 1.5 foil backed insulation installed, so no draughts up there and a bit of insulation. But the rest of the timber walled and floored house (an old cottage) is draughty and relatively uninsulated (there some insulation in some walls, but there are cracks in others!).

Last Christmas I bought a Kogan reverse cycle portable air conditioner for $300 with free delivery. It lives in the living room, which is small but semi-open plan. I only used it on really hot days, and it was able to keep the temp down to about 27 degrees near the ceiling (that happens to be where there's an appliance with a thermometer) whereas it gets to well over 30 without it running. The dogs love it. With a 2kw solar system on the new roof, i figure I am running it almost for free (I have a 20c net FIT).

I read somewhere that a lot of heat escapes back into the room from the outlet hose, and it certainly does get very warm. I insulated it with towels wrapped around it, and that seemed to improve the effectiveness a little. Getting a perfect seal around the outlet hose in a sash window is near-impossible, but in a draughty house probably not worth the effort anyway. The portable air con was a stopgap measure and a kind of proof of concept before diving in and buying the Mitsubishi already mentioned.

The heating function is nearly useless. The very cold nights where I live (minus temperatures most nights in winter) mean it is working at very low efficiency, and whatever heat it is pumping into the room, is negated by the air movement making it feel cooler. The heater function has only one fan setting, maximum, so you can't reduce the air movement, and it also makes it very noisy. Similarly, on a hot day you cannot expect your air conditioner to be working at max efficiency - those COP figures are calculated at standardised conditions, not 40 degree days.
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Re: Do portable air conditioners work?

Postby Gordon-Loomberah » Mon Sep 29, 2014 3:59 pm

IrishPete wrote:
But badly implemented in a rush so that greedy and shoddy cowboy installers managed to ruin it for everyone.


Yes there were cowboy installers, but I think the forces against energy saving operating through a certain media conglomerate had more to do with its demise.
I understand that the rate of deaths in the insulation installation business was actually lower during the period this program operated than the period immediately beforehand!
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Re: Do portable air conditioners work?

Postby Quokka2 » Mon Sep 29, 2014 4:41 pm

IrishPete wrote:Bit confused about the rude comments about Julia Gillard's home insulation program, as it was under Kevin Rudd.


Okay I got that wrong. The point of the observation is that there's not much point in insulating a house or a room if you're going to "air condition" it with an evaporative or portable cooler that replaces the air with outside air every few minutes anyway.
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Re: Do portable air conditioners work?

Postby IrishPete » Mon Sep 29, 2014 7:24 pm

don't all conditioners do the same?

anyway, you could tell me to fix all my gaps and cracks rather than buy a 300 dollar portable air conditioner, but that job is probably 5 figures...
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Re: Do portable air conditioners work?

Postby Quokka2 » Mon Sep 29, 2014 7:37 pm

1. Nope.

2. Much better investment.
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Re: Do portable air conditioners work?

Postby offgridQLD » Mon Sep 29, 2014 9:00 pm

The issue with portable air conditioners is the evaporator and condenser are both inside the home.

All the airflow used to cool the condenser taken from inside the home and pushed - vented outside through the exhaust duct. Naturally this created a vacuum in the house sucking more air into the home through all the little cracks- gaps. If your home was completely sealed in theory no air would flow any air.

In a split system AC the condenser is outside and just circulates air from the atmosphere around it. So you can seal up your home and trap the cool air flowing from the evaporator without drawing any outside air into your home. Even the old window/wall mount box air conditioners are separated . Condenser and fan hangs out the house cycling external air and evaporator is inside cycles the internal air.

In my view only way a portable unit could work is if you had two pipes . I suction pipe for the condenser and a exhaust pipe for the condenser along with some baffling . Or placing the entire unit outside on the porch and duct the cool air in though you would still need two tubes as the evaporator should by cycling the internal air.

So to sum up yes they are useless ;)
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Re: Do portable air conditioners work?

Postby Tracker » Wed Oct 01, 2014 8:22 am

IrishPete wrote:Bit confused about the rude comments about Julia Gillard's home insulation program, as it was under Kevin Rudd. Sensible people widely regard it as potentially effective on a number of fronts:


I have gone over the thread a number of times and see no comments.. :(
Do I need new glasses again..?

There are many economists who maintain that Australia would not have been adversely effected by the GFC..
So spending for the sake of spending, did massive damage to the economy.

Whilst Rude may have overseen the start of the insulation program , I think it was Gillard who removed it. (May be wrong - and it is irrelevant anyway )
Bottom line.. again... roof insulation could seriously impact on reducing power consumption.. we agree on that..!

The fact that our Government could not manage the program, only proved their inability to manage anything..
..
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Re: Do portable air conditioners work?

Postby Smurf1976 » Thu Oct 02, 2014 2:44 pm

offgridQLD wrote:So to sum up yes they are useless

Inefficient yes, but I wouldn't say they were useless as such.

Eg air coming into the building from outside at 35 degrees, exhaust air at 50 degrees. You're still exhausting more heat than you're bringing in, so some cooling is being done, but agreed it's not very efficient.
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Re: Do portable air conditioners work?

Postby Quokka2 » Thu Oct 02, 2014 7:28 pm

Smurf1976 wrote:air coming into the building from outside at 35 degrees, exhaust air at 50 degrees

A lot of that heat is being generated by the appliance itself - you can't assume it is all being removed from the space (refer first post ;) )
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