Need suggestion for "small" rm air conditioner <100sq ft


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Old 04-15-12, 04:16 PM
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Question Need suggestion for "small" rm air conditioner <100sq ft

Hello. Thanks for any suggetions. I'm baking here. Here is what I have.
I enclosed my car port and made the small utility rm it had into a study.
I moved the inside wall out a couple feet so the inside utility rm which is now finished is about 6' x 10'. Yeah kinda small and there are no windows. But hold computer desk and book shelves just fine.

Well I also had a duct extended into it and it just does not put enough air out. Rest of house is fine.

Does anyone have a suggestion on a small unit. I really wanted what I think is called a ductless. I dont want to go to the store and have something sitting on the floor. I would like to mount it to the wall up near the ceiling. The outside is brick so I only want to drill out a small hole etc of needed. Naturally that precludes me from something like a window unit where Id have to redo the brick etc to make a big hole.

Suggestions? Ive been looking at the ductless units or something similiar and seems most are like 10000 BTU and up. I'm thinking I only need something around 2500 or so to deal with the heat from the computer.

Thanks!
 
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Old 04-15-12, 06:38 PM
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You are correct, it sounds like you need a small unit, but smallest I have seen for ductless mini split systems is 9K btu. Many new high efficiency units have inverter drives and will adjust to the load demand.
 
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Old 04-15-12, 07:12 PM
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Cheapest is a window AC through the wall. You do need to make the opening big enough not to block the side vents in a brick wall but not hard to do. Cutting brick with a circular saw and a carbide blade is easy. No need to redo the brick wall.
 
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Old 04-15-12, 08:14 PM
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May be you should look into the existing duct and find out why the cold air does not come through, may be the problem is very easy to fix. for example, a bigger duct, or add a return duct, etc..
 
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Old 04-16-12, 08:38 AM
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I'd try to make the duct system deliver sufficient airflow to that room; add a large return air grille & duct back to the air handler...

What diameter is that duct feeding the room? Do the ducts need insulating, or are they leaking air? Are all the return areas sealed well?

You may need to put dampers on the branch take-offs so you can adjust the flow to the various rooms.

Check the blower wheel for lint build-up on the curved blades; clean if necessary & check the underside of the evaporator coil for lint build-up - clean if it needs it.

Is the blower motor set on high speed?

What size return air filter are you using? Don't use 1" pleaded filters; they will greatly reduce airflow!

What tonnage is you central A/C?


There is some more but this is a good start...
 
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Old 04-16-12, 03:55 PM
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no need for all that, get the smallest & cheapest you can at Home Depot or Walmart and dump the heat in the garage. The condensate might not even be a problem if you have a floor drain in the garage or seattle with a bucket. Many these day use a slinger fan and disipate the condensate into the air (removing heat). at worst you MAY have to keep the garage door open on really hot days... I disagree with HVAC ret on 1" pleats,... have never had a lack of airflow on a PROPERLY installed unit. I have had to remove coils to clean them though on AC evap coils where a fiberglas filter failed to remove the contaminants.
 
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Old 04-16-12, 05:15 PM
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Thanks. Well my current unit is a 3 ton. House was built back in the 70s. All the other vents have good air flow. This one was added off an existing one. I was told at the time that I would prob need the ductwork redone in order to get the correct flow out of it to this room. Needless to say I didn't have the money at the time since the old unit went out. Now the attic has been reblown and you cant even see the ducts. It would just not be feasable I think to go that route.

I dont have garage to dump anything into. This is a finished room now. I was really wanting to NOT do a window type unit just for the looks etc. That was mainly why I liked the small looking slim units that you mount up near the ceiling. I dont need heating, just cooling. Hmmmmm.

Is there something like a floor model like you get in the big box retailers that you can mount horizontally on a wall that maybe plugs in and I can run a drain line out? Guess I might have some limited options
 
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Old 04-16-12, 05:39 PM
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Looks like you already made your mind.
 

Last edited by hvactechfw; 04-16-12 at 05:41 PM. Reason: removed advertisement
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Old 04-16-12, 06:24 PM
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The portable ones are more expensive but okay if you get the two duct ones.
 
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Old 04-16-12, 07:06 PM
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All the other vents have good air flow. This one was added off an existing one. I was told at the time that I would prob need the ductwork redone in order to get the correct flow out of it to this room. Needless to say I didn't have the money at the time since the old unit went out.
Never enough money to do the job correctly but always enough to do it over.

Balancing of your ductwork MAY help (assuming you have balancing dampers) but a properly sized duct to this room is what is really needed. Any half-way decent portable A/C will likely cost as much as proper ductwork. The portable will also be considerably noisier than the proper duct AND will take a fair amount of electricity to operate.
 
 

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