# Convert portable AC to mini central AC. Any reason why this would not work?



## KarlJay (Dec 9, 2009)

I have one of those portable AC units, it's a DeLonghi. I use it when I want one room cooler.  It has a 5 gal water tank that needs to be refilled every day or so. It's a freon/compressor based AC, not a swamp cooler, I understand it uses the water to prevent driping all over the floor.

Does your's use water? If so you'd have to get some kinda auto-fill thing. 
Does it require a drain?


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## Red Squirrel (Jun 29, 2009)

Mine is actually self evaporating, so from my understanding, the water goes into a temp container, and it is occasionally pumped over the condenser coils, helping to cool them off better, and causing the water to get hot and evaporate at the same time. There's a small plug and if I pull it, water comes out, but from a whole summer using it, I never had it stop on me where I have to remove any water. So I think I'd be ok in that sense. I don't have to actually add water to it, either.


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## hvactech126 (Nov 11, 2010)

never mind, in not even going to comment


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## Red Squirrel (Jun 29, 2009)

I forgot about this thread, and I was thinking about this project again.

Any reason why it should not work, or any improvements I should do to ensure it does work?

I made a diagram of my proposed plan. Also I would probably use 6" duct instead of 5". This gives me extra air volume in case I get a bigger unit later down the line. I figure if I will do this, I better do it now as in the next couple months when all the snow starts melting, it will be too hot to work in the attic. 

I'd probably get something like this for the booster fan:

http://cgi.ebay.ca/6-Carbon-Air-Fil...332?pt=LH_DefaultDomain_0&hash=item3cb6762b04

I may decide to not hook the AC unit directly to the pipe, I may just leave it in the server room where the fan will be and it will just grab the cold air from that room, and I will let other air enter. That room is not built yet though, but I plan to build it soon. By doing this I can let the AC unit's thermostat do it's job better. I can keep that room at 20 degrees which should result in a more or less constant temperature in the upstairs room that is getting this air.


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## pyper (Jul 1, 2009)

If it gets hot in your attic, you'll need a ton of insulation on the ducts.

12k but isn't very much -- about a mid-sized window unit. If it doesn't get very hot where you live and you have good insulation, then 12k might be enough. Where I live 12k will work for a single room or maybe two.

You want your intake to be the relatively cooler, dryer air inside the house, not the outdoors. 

I suspect your main difficulty will be getting good enough air flow through the small duct you are thinking about.


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## hvactech126 (Nov 11, 2010)

returns? just adding conditioned air will not cool.


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## Red Squirrel (Jun 29, 2009)

Oh yes I will be using lot of insulation. I have to or I could get condensation and heat loss issues in winter. I will use insulated duct, air seal it very well with vb tape, and then lay lot of fiberglass over, probably R40 or so. (existing insulation which I'll be flipping over then putting back) A 500CFM unit should probably do the trick as far as air flow, I would think. The intake for the indoor air will be basement air. The intake in the picture is for cooling the condenser, so that air just goes back outside. The unit itself was used last year to cool my office and bedroom and works quite well, so hopefully it should be able to do the 2 rooms with this duct setup. I'm not too concerned about the spare, I will only open that duct on a needed basis and compensate. In fact if it can't cool even two rooms at once, I can just open/close the vents as required, still easier then hauling the unit around. 

Think I should go bigger then 6" duct? I can easily do that, but I'm thinking that should be enough.


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## Red Squirrel (Jun 29, 2009)

hvactech126 said:


> returns? just adding conditioned air will not cool.


The existing hvac ductwork should do I'd think. If I'm pulling basement air and pushing it through those vents, the easiest path for replacement air is through the ductwork, crack under the door, etc. If that theory really does not work, I can easily add dedicated returns too.


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## hvactech126 (Nov 11, 2010)

i'm done. its not a good idea thats all im going to say


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## HVACDave (Oct 16, 2007)

Sorry to be a downer on this project, but 126 is correct, this is a bad idea. 

Any time you are using one of these portable type units that vent out the wall you are depressurizing the space that the unit is cooling. That means you must be bringing air back into the space somewhere else. That air you are bringing in is likely the same temp as the air outside, which really means you are trading cool air in one room for warmer air in another.

Furthermore, to add ducting and a booster fan, control and power for said fan, make penetrations into your attic space in various locations, insulate ducting etc. Why not put the energy and or cash into purchasing a ductless split and be done with it? At least that way you know you will be happy with the result and your noise issues will go away.


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## Red Squirrel (Jun 29, 2009)

This will only cost about 200 bucks, some aluninium pipe, insulated flex pipe, misc hardware, the fan itself. vs $5,000 and for the 2 months of the year that I'll use it, I can't justify paying for central AC or a ductless split unit. Maybe in the future. 

But if this won't work, then I might stick to just hauling the unit around. As for the cooling of the compressor, I modded the unit so it uses outside air hence the intake/exhaust pipes. I found this made a huge difference last year.


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## hyunelan2 (Aug 14, 2007)

Why not just get a window AC unit and call it done? If you only need it 2 months out of the year, that seems like the way to go to me. 

You can easily get one for the price of materials your idea would cost.


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## Red Squirrel (Jun 29, 2009)

I already have that big unit, and my windows are all crank, otherwise that's what I'd do.

I have considered getting a through the wall unit though, but I'd need two. the office and bedroom are the most critical to cool. Canadian tire had a nice one, it's like 30,000 BTU. Would cool the whole house, the garage, and the neighboor's dog house. :laughing:


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## hyunelan2 (Aug 14, 2007)

You could get one through-the-wall unit, and leave what you have now in the other room.


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## Red Squirrel (Jun 29, 2009)

I may do that, the through the wall could go in the bedroom and the existing in my office. I did install a dedicated 20 amp circuit for it so may as well use it. How well do those through the wall units work in winter? Are they well enough insulated and sealed so I wont have a massive heat loss?


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## zootjeff (Jul 11, 2007)

Red Squirrel said:


> This will only cost about 200 bucks, some aluninium pipe, insulated flex pipe, misc hardware, the fan itself. vs $5,000 and for the 2 months of the year that I'll use it, I can't justify paying for central AC or a ductless split unit. Maybe in the future.
> 
> But if this won't work, then I might stick to just hauling the unit around. As for the cooling of the compressor, I modded the unit so it uses outside air hence the intake/exhaust pipes. I found this made a huge difference last year.


I bet you could get it to work. You might not have enough cooling capability, but I don't see why it wouldn't work. It just might be a hard thing to explain if the house burned down for another reason..


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## alecmcmahon (Apr 30, 2010)

You NEED returns, and even if you did it is probably way undersized. 

Dont bother.

The purpuse of Air Cond. is to REMOVE HEAT FROM AN AREA..... how will your rooms properly cool if there are no return air?


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## Red Squirrel (Jun 29, 2009)

alecmcmahon said:


> You NEED returns, and even if you did it is probably way undersized.
> 
> Dont bother.
> 
> The purpuse of Air Cond. is to REMOVE HEAT FROM AN AREA..... how will your rooms properly cool if there are no return air?


Naturally two bodies of air will want to equalize, if they are able to. So if I depressurize the basement and pressurize the upstairs then naturally air will be pushed down through vents, cracks etc. Though, I have no furnace return in the basement, so to fix that I may actually add one right where the upstairs return is, so that would create a direct path. But TBH, I don't think the returns would be an issue. I installed an inline fan for my bathroom and when I close the bathroom door, I can feel air coming out of the furnace vent. In fact it makes the shower curtain move. Those inline blowers really do have quite a lot of balls.

The only issue is hot air rises, and I'll be trying to push it down, so that may possible pose a challenge. It was an idea, but I'll probably drop it.


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