Air Conditioning A Shop - Again

[Glen Blanchard]

A month ago or so, there was a thread concerning the use of portable (not window) A/C units. As I remember, there were a couple of SMC members successfully utilizing these units and a couple of brands were mentioned and some sources given as well I think. Was in Home Depot today and noticed they now stock this type or A/C unit. It's on casters and even has a remote control. 10,000 BTU recommended for spaces up to 400 sq ft. I think the manufacturer is "Everest". The price was attractive at $499. Anybody using one of these? I'm gonna need to buy something for my 1 car garage soon as the Texas summer is approaching.

[Cecil Arnold]

Glenn, I've seen them at the HD and have only one comment that you might want to consider. The air will be recirculating through both sets of coils in the unit. My concern is that fine sawdust will collect on the coils, both condenser and compressor, and reduce the efficency of the unit. I know this happened to a window unit I had in my shop here in Houston. I replaced the 7000 btu unit with an 11,500 unit in my 11X23 shop, then added a pre-filter to catch most of the sawdust. Even with insulation I can only maintain about a 15 degree differential with a few machines running. I have watched the temp. go up 5-6 degrees with the TS, DC, and air filter going for 10-15 min.

[Ken Garlock]

Hello Glen. I have two concerns with your plan to A/C your garage. First, you need to consider what, if any insulation, you have in the walls and ceiling. It is common to NOT have any, and as a result, it gets very hot in a garage.
Second, you can't get something for nothing. By that I mean that you need to have a means to exhaust to the outside the heat generated, and removed from the air. Not providing an exit for the heat from the A/C unit will do nothing to cool the garage, just make TXU happy. In the better setup, you need to supply outside air to the condenser part of the A/C and then send that heated air to the outside.

Personally, I would not use a portable self contained A/C for anything other than an emergency unit. Of course it it were someone I didn't like, I would highly recommend it. :eek:

A better solution, IMO, is to get a split unit. With a split unit, the compressor and condenser coils are outside, and there are two small runs of copper tubing thru the wall to the evaporator and fan hung on the wall inside the area to be conditioned. Should you decide to move, remove the unit, and patch the holes in the wall. POC. :)

[Glen Blanchard]

Glenn, I've seen them at the HD and have only one comment that you might want to consider. The air will be recirculating through both sets of coils in the unit. My concern is that fine sawdust will collect on the coils, both condenser and compressor, and reduce the efficency of the unit.

Yep, I had thought about that too. Your idea of a pre-filter might be worth trying. Others seem to be having success with these though.

[Glen Blanchard]

Hello Glen. I have two concerns with your plan to A/C your garage. First, you need to consider what, if any insulation, you have in the walls and ceiling. It is common to NOT have any, and as a result, it gets very hot in a garage.
Second, you can't get something for nothing. By that I mean that you need to have a means to exhaust to the outside the heat generated, and removed from the air. Not providing an exit for the heat from the A/C unit will do nothing to cool the garage, just make TXU happy. In the better setup, you need to supply outside air to the condenser part of the A/C and then send that heated air to the outside.

Well, the walls, door and ceiling are insulated, but leaks do exist around the garage door. The units I am looking at have a hose that must be exhausted into a non-conditioned space (e.g. outside). Ya know, I would not have given much credence to these portable units if it were not for the apparent successes mentioned on this forum. Am still undecided, but it sure would be nice to continue woodworking throughout the summer.

[Charlie Plesums]

I ran into a wood turning site where the shop did both dust isolation from the residence and heating/cooling by using an small exhaust fan in the shop - similar to a kitchen exhaust. This created a negative pressure in the shop which pulled conditioned air from the house, and kept most of the dust from entering the house. It may not be the most efficient system, but the simplicity is attractive. It may not provide perfect temperature control, but it may make things tolerable when the outside weather is bad.

Has anyone considered/tried that alternative in a garage-size shop?

[Bill Fields]

Glen --and others--

I live in hot/dry Phoenix--have a 3-car garage of which I claim 1 space for storage of my all-mobile based tools. BUT, all spaces and a large garage/driveway apron for rolling out the tools and doing work.

Humidity is mostly well below 30%. Frequently 15-9%.

Downside for this arrangement is that I have to ROLL them back in in the evening --or--in the event of RAIN.

In summer it is a case of waiting till the sun gives shade to the driveway in front of the garage doors, mostly.

My solution to cooling in Phoenix summer is MOVING air--namely well-placed strong fans.

"Winters" are somewhat different.

BILL FIELDS

[Jeff Sudmeier]

From what I have read (on pop up camping forums) these self contained units can be the cat's meow. The thing is you still have to calculate your BTU needs and figure out how to protect them from dust.

[Mark Duksta]

Here are some pics of the units I have in my (messy) garage shop. I have two of them. A 10K and 12K BTU unit. They do a good job except in the very hottest part of the summer. My insulated garage door faces west and gets the full force of the afternoon sun. Once the tree I planted gets large enough I should be OK. I want it cooler still. This was the cheapest way to go without cutting a large hole for a window unit.

Mark

[Glen Blanchard]

2 questions Mark.....

1. Why do you have 2 units? 2 car garage? Supposedly a 10K BTU unit is supposed to handle a 20 x 20 space.

2. Have you done anything to minimize the problem of sawdust getting onto the coils?

[Mark Duksta]

2 questions Mark.....

1. Why do you have 2 units? 2 car garage? Supposedly a 10K BTU unit is supposed to handle a 20 x 20 space.

2. Have you done anything to minimize the problem of sawdust getting onto the coils?

One unit wouldn't even come close. It is a two car garage. It's well insulated and I tried to make it air tight as possible. I put a seal around the garage door. I think the published cooling power of these units are for optimal conditions.

I have not done anything special to minimize the dust coming into the filters. I am in the process of installing a new DC. I hope that helps. I blow the units out regularly with the compressor. I am somewhat hesitant to add an additional filter to the units. I'm concerned that the added resistance would be bad for the units. I might try it with one of them this summer as a test though.

Mark

[Cecil Arnold]

I've heard somewhere that if you increase the aux. filter size (for example increasing it by 1.5-2 times the regular filter size) it doesn't effect the flow noticeably.

[Tom Jones III]

Funny this comes up again now. This weekend my family gave me a window AC (for my birthday) for my shop here in Houston. When my family does research, they really do it well. They found not one but two people who install A/C for a living, live in TX, has a 3 car un-insulated garage and cools it with a window unit. Both people said it is not going to make it cool like inside your house but will keep it usable through the hottest part of the summer. Both of them said an 18,000 BTU unit is the minimum for the above space, even when only using one stall. For good measure they consulted two more experts and they were unanimous in that you could acheive some level of comfort and they were also unanimous that it would require a minimum of 18-24,000 BTU.

The unit they purchased was from Home Depot and is evidently a relatively new brand, "LG". The prices on these units are pretty cheap compared to some of the others although I don't know exactly how much it was. There is a 5 year in-home warranty. The unit I received also has a timer feature so that you can either start the unit or stop it on a timer. The filter that comes on it is plastic and can be easily removed and hosed clean.

[Charlie Plesums]

Supposedly a 10K BTU unit is supposed to handle a 20 x 20 space.

My home air conditioning system provides roughly 25 BTU per square foot, so that estimate is reasonable in a residential environment, well insulated, no machinery, surrounded by other conditioned space rather than outdoors on 2-3 sides plus ceiling. We use a separate unit in our office when we don't want to run the whole house A/C - about 4000 btu "extra" just to take care of the various computers and monitors.

The 18-24,000 BTU for the garage shop sounds very logical and more likely sufficient than the vendor claim of 10,000 BTU for that amount of space.

[Glen Blanchard]

The 18-24,000 BTU for the garage shop sounds very logical and more likely sufficient than the vendor claim of 10,000 BTU for that amount of space.

I would assume then, that 10,000 BTU would be a reasonable estimate to cool a one car garage?

[Ken Garlock]

Well, the walls, door and ceiling are insulated, but leaks do exist around the garage door. The units I am looking at have a hose that must be exhausted into a non-conditioned space (e.g. outside). Ya know, I would not have given much credence to these portable units if it were not for the apparent successes mentioned on this forum. Am still undecided, but it sure would be nice to continue woodworking throughout the summer.

Glen, it sounds like you have the bases covered. My main concern is the need to SUPPLY AND EXHAUST the air blowing over the condenser. If you can provide a means to supply and and remove air, it looks like you have a workable solution. How would you do that, cut holes in the garage door?

Go for it :)

BTW, it would be a good idea to put some additional insulation on the inside of the garage door, if you haven't already...

[Glen Blanchard]

If you can provide a means to supply and and remove air, it looks like you have a workable solution. How would you do that, cut holes in the garage door?

Well, I have a 3 car garage, but in fact it is 2 garages (a one car which is my shop and a two car, perpendicular to each other) connected by a 6' wide walkway. I have partitioned the spaces one from the other in the walkway area, and plan on running the ductwork to the two car garage.