Portable A/C unit... any suggestions ?

[wmartins]

I have a small woodworking workshop setup in my one car garage (230 sq. feet) which I use mostly on the weekends. The insulation is not very good but I'll improve it. Being in Florida, temperature reaches 90's during the summer. Anyway, I was thinking on a 12000 BTU unit, but with so many brands, models, and $$$, I was totally confused, then I decided to read the review on a couple of models, and I got more confused. I trust people on these forum, so I'd appreciate your recommendations/experiences with this kind of cooling systems.
Regards,
Walter.

[gwyneth]

By 'portable' do you mean the kind on casters that doesn't need a window or outdoor outlet?

There was a thread here a few months ago about a.c. and a Florida garage.

[LCHIEN]

Air conditioning BTUs required depends upon the heat flow.
You would need a very small A/C in you tried to cool any sized space with perfect insulation (no flow allowed). Given that all insulations are not perfect, then you will flow heat or cool (the equations are the same no matter which direction the flow).

Heat flow or loss is the sum of the flow through every inch of the wall floor and ceiling surfaces in your shop you want to keep cool.

Heat flow is proportional to the temperature difference bewteen the outside and the inside, so twice the temp difference maintained requries twice the BTUs with the same insulation.

the short story is you calculate the wall area, and get the insulatiion rating (like R-9) and look in the table for BTUs per degree per square foot for that insulation. multiply the table value x degrees difference times sq footage and you'll get BTUs.
Then you take the ceiling area and the insulation rating and the attic temp and calculate BTUs.
Then you take the concrete slab floor and the ground at probably 70 or 80 and there's probably not too much loss because of the small temp differential.

Then you take windows and doors, they lose heat flow becuase they are not as good insulators as fiberglass-filled walls, calculate the additional BTUs lost by the area and temp differential.

So you add all the BTUs and that's the rating you need
if youwant the A/C to run full time on the hotest day you picked.

Probably double that so the A/C runs 50% duty cycle or to make up when you open the doors or want it to cool down reasonably quick after being off.

The tables are all available in A/C sizing programs or web sites if you do enough searching.

I calculated about 14,000 BTU for a garage 425 sq feet in Houston (100 degree days) with a few windows and doors. and typical home construction insulation.

So with less aggressive insulation 12,000 BTU is probably OK for 230 sq ft.

[thrytis]

From everything i've been able to find, you want one with two hoses, one for the air intake and one for the exhaust. The no-hose units just blow cold air out one side and hot air out the other, so it isn't going to do you any good unless you're standing right in front of it. The one hose units sucks the air out of your room and blows the hot air out the exhaust. Warm outside air is sucked in through cracks to make up for the air being blown out the exhaust. The two hose units suck air from the intake hose and blows the hot air out the exhaust, so all of your cooled air stays inside.

There are calculators out there that'll give estimates on how many BTUs you need based on your space, insulation, and orientation to the sun. A web search should pull up several.

[wmartins]

Yes, I was thinking on a 1 or two hoses units, for 12000 BTUs they are in the range of $300-600 and up. Basically, I was looking for a recommendation on a specific brand or model you are familiar or you own.
However, all responses are welcomed.
Thanks,
Walter.

[Uncle Cracker]

Those sold in HD and Lowes are probably about the cheapest, and you might be able to get a deal on one as the season ends, maybe on a display unit that's not beat up too badly. You might also do well to use a reflective coating on your roof, and try to put some insulation in your shop, or maybe at least a vapor barrier. In Florida, much of the A/C costs go into removal of the humidity. Unfortunately, this also means that roll-around unit is gonna suffer in this area. Without a condensate drain, and overabundance of coil water is a problem. Most units use a slinger fan to throw the condensate up on the "hot" refrigerant coil, but it's hard to get rid of a lot of condensate that way. If you find one with a condensate pump and drain line, they work better.

[gwyneth]

In Florida, much of the A/C costs go into removal of the humidity. Unfortunately, this also means that roll-around unit is gonna suffer in this area. Without a condensate drain, and overabundance of coil water is a problem. Most units use a slinger fan to throw the condensate up on the "hot" refrigerant coil, but it's hard to get rid of a lot of condensate that way. If you find one with a condensate pump and drain line, they work better.

Eight years after moving from Florida it still amazes me that separate dehumidifier units are so much more common up north than there.

Would a dehumidifier ($100-150) help reduce load and energy usage?

[LCHIEN]

Those sold in HD and Lowes are probably about the cheapest, and you might be able to get a deal on one as the season ends, maybe on a display unit that's not beat up too badly. You might also do well to use a reflective coating on your roof, and try to put some insulation in your shop, or maybe at least a vapor barrier. In Florida, much of the A/C costs go into removal of the humidity. Unfortunately, this also means that roll-around unit is gonna suffer in this area. Without a condensate drain, and overabundance of coil water is a problem. Most units use a slinger fan to throw the condensate up on the "hot" refrigerant coil, but it's hard to get rid of a lot of condensate that way. If you find one with a condensate pump and drain line, they work better.

"Most units use a slinger fan to throw the condensate up on the "hot" refrigerant coil, but it's hard to get rid of a lot of condensate that way."

that just puts the humidity back in the room air... not a very good solution if humidy is part of the problem.
And you have a lot of it.

That is defiantely a problem for a portable A/C in Fla . or anywhere on the Gulf coast.

[Uncle Cracker]

that just puts the humidity back in the room air... not a very good solution if humidy is part of the problem.

Not necessarily. If the unit is exhausted to the outside, as most are (two ducts, one bringing in outside air, the other sending sending heated air back outside) then the humidity is indeed exhausted (provided it doesn't re-condense right in the ductwork ). But that does not prevent so much of the already limited energy from being used to get the water out of the inside air.

[jhart]

I have a number of units that we use in our home and in some of the rental units. Most of them are smaller window type units. Not sure if some of these brands are still available.
Quasar 11000 btu - excellent 11.0 Seer - usually able to cool the whole downstairs (about 1400 sq. ft.) used in conjunction with two ceiling fans.
Whirlpool 6500 Btu - has done a good job in a bedroom 9.8 Seer
Goldstar 5500 btu - don't waste your money
Sharp 5500 btu - seems to do an ok job on a medium sized area.
Maytag roll around with vent that fits in the window. - 8000 btu - does a good job - 9.8 Seer. Nice too be able to quickly put vent in and out of window, as is the only window in the bedroom, if you like to get fresh air on a nice day/nite. Was expensive $599 when we bought it. have seen other brands for less at HD this past year (now about $399)

Just picked up a GE 10,000 btu At Sam's about a month ago for $279. Havent used it yet but will replace the Quaasar which is over 11 years old and starting to act up.

Biggest thing to look for is the SEER rating. Most of the discount places are about 9.8 or 9.9. The higher the rating, the more efficient. Can really add up on the amount of electricity used/saved
For the apartments, the tenants pay for the electricity, and feature of A/C is more important to them than SEER rating. Plus they abouse them, so we typically look for inexpensive ones.

[gwyneth]

Goldstar 5500 btu - don't waste your money

After extensive price- and review- shopping, I got the Goldstar 6500 at Circuit City last summer for about $140, shipped, and it's been terrific. Very energy efficient, fast cooling, and the dog (for whose benefit it was purchased) learned to bring me the remote control when he wanted more cooling.

Like many other appliances and household electronics, digital controllers and solid-state circuitry has resulted in much better operation.

However, neither Minneapolis nor northern Wisconsin offer the same challenge to air conditioners as Florida.

[LCHIEN]

... Very energy efficient, fast cooling, and the dog (for whose benefit it was purchased) learned to bring me the remote control when he wanted more cooling...

Why don't you teach the dog to use the remote and cut out the middle man.

"on the internet, no one knows you're a dog."

[ironhat]

In my well insulated, 336 sq ft shop my 8K btu unit barely breaks a sweat. I got it at the end of the summer last year for ?? - something like $85. If I don't have a long-term project on the table I leave it off but even for the occassional day in the shop I'll get it started a few hours (or the night before) ahead of time and I'm good all day.

[Tom Hintz]

I used a Sharp 10,000BTU AC unit (single hose) in my garage-based shop this summer (40+ consecutive days over 90-degrees, a record) and it did a surprisingly good job. I have insulated walls and insullated steel garage doors but the front of the shop is fully exposed to the sun throughout the afternoon, not a good deal with this clear blue Carolina sky sometimes.
I know single hose units "don't work" so mine must be busted or something because it does. It's not cold in the shop but I doubled my time out there this summer so it was a major success for me.

[gwyneth]

Why don't you teach the dog to use the remote and cut out the middle man.

"on the internet, no one knows you're a dog."

No thumb; and because the dog doesn't pay the utility bills, the humans who do get the final OK on air conditioning use.