Cooling My Garage
#11
  
I am sure that there have been other threads on this general topic in the past, but nothing comes up in my searches.

I have been looking for quite a while for a way to cool my garage/workshop. Although I am in Maryland, it gets unbearably hot for me in the summer months.

My garage is 21'x21', so it seems that a window air conditioner could handle the task. Unfortunately, my garage is windowless. I’ve considered a portable, but I would still need to create an opening to outside to vent the hot air and moisture.

I recently learned about mini-split AC systems, and it appeared that even a low-end system could provide enough cooling for my needs. So, I contacted an HVAC contractor to get an estimate. 

He immediately told me that I should not get a mini-split system, because the filtering would be inadequate for a wood shop. He instead recommended a small split system, using a Trane XR14 air conditioner, and a air handler in the attic. The unitl ooks like a smaller version of the heat pump that handles the rest of my house.

His proposal for this was $6700. This way over what I can justify for cooling one room for part of the day for three to four months. 

I’d like to get some opinions about whether the contractor was correct about the inadequacies of a mini-split system, and if there are other options I have missed. It seems that it would be far less expensive to set up better filtering for a mini-split, or to have a window or a vent installed in the garage. I don’t doubt that the contractor’s solution would be superior, but at a cost I can’t stomach.

Hank Gillette

Thanks for reading.
Hank Gillette
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#12
  Re: Cooling My Garage by hankgillette (I am sure that there...)
Good post.  My oldest bought a house in the Houston area, with a 2-1/2 car detached garage.  But it does have the main panel in there, so that's half the battle.  Zero insulation, though. Sad

He has a pretty big home gym in there, with professional equipment like squat rack and zillions of plates and stuff like that that he's accumulated from friends who are/were pro's in the business.  I gave them a 30" pedestal fan a few years back for their last house, also in the same area, but I know he wants to add air conditioning.  And his DW would like to jump around to music without the whole world watching.

So I've been eyeballing sleeve units, which seem to have the most bang for the buck, especially for a space that's only used for relatively short time per day.  14,000 BTU/hr units with wifi access (for remote turn on/turn off, for instance) for $730 (plus the cost of sleeve, which is cheap), or without wifi for $610.  240V in that size, but I can help with that and the sleeve installation when I'm there next, which will be soon (baby boy due in September Big Grin ).

So that's a consideration, and for what a replacement would cost, you could replace it every 5 years and still be ahead of the game.  But being in a garage, you could always fire up the garden hose and wash out the evaporator every so often.  Maybe add some extra filtration to the intake side.

It's a thought at least.
Tom

“This place smells like that odd combo of flop sweat, hopelessness, aaaand feet.”







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#13
  Re: Cooling My Garage by hankgillette (I am sure that there...)
I'm fond of the GE Zoneline units over a regular window style air conditioner installed in the wall.

1. They are quiet.
2. More efficient and effective.
3. Can be replaced when it finally wears out and you keep the case you already have. (The replacement unit fits right into the existing case (sleeve)).
4. Easy to remove and take outside to wash it.
5. Will heat and cool- or just cooling.
6. Can use a wall thermostat and/or separate sensor.
7. More durable.

It will require a 42"x16" hole in the wall, but you'll never have to change the hole size again.

Mini-splits are not good in my opinion in dusty shops- hard to clean and the drains get stopped up.

My next choice would be what TDKPE suggests.
"There are no strangers- only friends I haven't met.
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#14
  Re: Cooling My Garage by hankgillette (I am sure that there...)
I have zero experience with the mini splits, but it seems to me that quite a few folks use them in their shops and I don't recall anyone saying it was an unmanageable problem with the dust. Maybe one of them will chime in with their opinion. That said I use a window unit (it's actually one of the sleeve type) but I don't have near the heat problem you have. I'm always skeptical of contractor recommendations when they have a hugely more expensive solution.
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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#15
  Re: Cooling My Garage by hankgillette (I am sure that there...)
First question:  Is the garage insulated? And what is the ceiling height.  Or more simply what is the cubic foot area that needs to be cooled?

If it has a ceiling then probably 21' x  21' x 10' = 4,410 cu. ft.

One on-line BTU calculator indicates about 14,000 btus to cool that size room assuming average insulation. 

Two 7,000 BTU window units placed through the wall would probably do the trick.  It would probably provide better circulation than a single unit with 14,000 BTUs.  They are also lighter and easier to install.

A powerful exhaust fan would quickly expunge any superheated air and would allow quicker cooling.  I have a whole house attic fan and turning that on for 10 minutes to clear the attic of superheated air allows the house to cool quicker with the AC than otherwise.

Get AC units with wireless remotes and order a spare remote as soon as you get yours.  My AC in my bedroom works fine, but the wireless remote failed and replacements are not available.  They cost about $20.00 when they were available and I wish I had ordered one back then.
No animals were injured or killed in the production of this post.
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#16
  Re: Cooling My Garage by hankgillette (I am sure that there...)
I already had two windows in my shop, so a little different than your situation, but what I have in my 2-car garage in central IN (24x26x10') with well insulated walls and ceiling above (attic) is a 15,000 BTU window unit. This is the biggest one they make that runs on 110V. I had an 8,000 BTU, which worked OK, but couldn't keep it really cool if it got and stayed around 90*. I would have kept the 8k, but ended up with a temporary need for a bigger unit for something else so once I had it I swapped it out in my shop. I know that's not what you asked about, just pointing out that a window unit will keep your shop comfortable if you can find a way to put in a window. My window AC was ~$500-$600. That plus a window is probably way cheaper than what you're looking at.

If you go the window AC route, I'd put in a window rather than just frame a hole. Allows some flexibility in AC units plus the (IMO) benefit of having a window.
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#17
  Re: Cooling My Garage by hankgillette (I am sure that there...)
Most minisplits have those funny cheap filters like window units have. They don't catch much of anything. I have a 22K btu window unit in my insulated 20x40x10 insulated shop and it's enough IF you keep it cool. If you want to use it intermittently you will need a much larger unit than the calculators show as they are sizing for what it takes to maintain temp not to quick cool. 

    The units described above are great bang for the buck. Also known as PTAC or Hotel units and come in heat pump varietys as well. That is a route I would look at as well. For a shop building I like package units as it's all outside just hook up power and ducts. If it fails its a quick swap out but that is for larger buildings though.


     Oh and Cooler mentioned the attic fan. I have lots of roof venting but I have found here in TX that you really can't get enough flow with soffit vents as the screens block way too much airflow. I have taken to leaving the attic hatch open in the garage in the summer and cracking the garage door open and that makes a huge difference in attic temps and in vent temps in the house as well. 
 
       What I want is a double shafted motor with squirrel cage fans on both sides. That way one would bring air into the attic and the other would discharge hot air at the same rate so no attic pressurization happens.
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#18
  Re: Cooling My Garage by hankgillette (I am sure that there...)
I have a mini split in my 24 x 30 wood shop.  The temps and humidity in VA can be brutal.  My woodshop is well insulated, but the mini split keeps it at an even 70 degrees in the summer and 68 in the winter.  The electric bill went up just about twenty dollars a month, since I haven't been running the small window unit for hours in my old shop.  A good trade.

I have a HVAC tech come twice a year to service the home ac, furnace, and the mini split.  He cleans the filters and the inside and outside coils.  The dust isn't an issue.  I have both a large Jet Cannister Dust Collector I move from machine to machine... And the overhead jet Air Filter for the smaller airborne particles.

My contractor installs these systems in cattle barns, Big cattle barns.

Big Grin
Jim in Virginia
You can tell a lot about the character of a man -
By the way he treats those who can do nothing for him.
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#19
  Re: Cooling My Garage by hankgillette (I am sure that there...)
I'd probably still consider a mini-split and find a way to provide some filtering.
 
"My mortgage self-identifies as a student loan."
... Kizar Sozay


Neil Summers Home Inspections
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#20
  Re: Cooling My Garage by hankgillette (I am sure that there...)
(08-22-2019, 02:19 PM)hankgillette Wrote: I am sure that there have been other threads on this general topic in the past, but nothing comes up in my searches.

I have been looking for quite a while for a way to cool my garage/workshop. Although I am in Maryland, it gets unbearably hot for me in the summer months.

My garage is 21'x21', so it seems that a window air conditioner could handle the task. Unfortunately, my garage is windowless. I’ve considered a portable, but I would still need to create an opening to outside to vent the hot air and moisture.

I recently learned about mini-split AC systems, and it appeared that even a low-end system could provide enough cooling for my needs. So, I contacted an HVAC contractor to get an estimate. 

He immediately told me that I should not get a mini-split system, because the filtering would be inadequate for a wood shop. He instead recommended a small split system, using a Trane XR14 air conditioner, and a air handler in the attic. The unitl ooks like a smaller version of the heat pump that handles the rest of my house.

His proposal for this was $6700. This way over what I can justify for cooling one room for part of the day for three to four months. 

I’d like to get some opinions about whether the contractor was correct about the inadequacies of a mini-split system, and if there are other options I have missed. It seems that it would be far less expensive to set up better filtering for a mini-split, or to have a window or a vent installed in the garage. I don’t doubt that the contractor’s solution would be superior, but at a cost I can’t stomach.

Hank Gillette

Thanks for reading.

I bought a window AC with a wall sleeve for my 600 sf shop.   Cut a hole in the wall, flash in the sleeve, install the unit.  done.    $300 instead of 1500 for a split system.  I only use it for a month during the hottest times of the year and keep it covered with an air tight box when not in use.  When using it I blow the dust out every few days.
WoodNET... the new safespace
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