Thoughts about cooling a garage layout?

Model Railroader Layouts and layout building
1

While my Tonopah and Tidewater depicts the arid desert of Nevada, actually operating it in a 115 degree heat is probably a bit too realistic. It has moved out of a spare bedroom with house AC into a 11x20 3rd car garage attached to my house in the Nevada desert. This garage is an integral part of my house and the attic is above the garage. There is access to the attic in the roof of the garage. I’ve insulated the garage door and it heats up pretty fast with a small electric heater.

The big question is cooling it in the summer. My first two thoughts are to have a AC company run a duct from the house AC into the garage thru the attic. It would make the garage part of the house cooling system. The alternative would be to install a small AC system like the Mitsubishi systems sold at Home Depot with the compressor outside and a single cooling unit attached to the inside wall. Does anyone have any experience with doing this? What are the problems I am likely to encounter? Any other ways to cool this down in the summer? Thoughts and opinions? Thanks.

2

Is your house heating system also hot air, using the same ducts as the AC? If so, that becomes a more attractive option, as you can use it for both heating and cooling. EDIT: NO! Don’t do this! See the LION’s post, and mine below that. You do want the ability to shut down the garage heating and cooling when not in use, though.

I live in New England. My heating system is forced hot water, and the house has no central AC system. So, we’ve put in a number of through-the-wall AC units that run on 120 volts. This gives us easy room-by-room control.

Are the garage walls insulated? If not, it would be a worthwhile investment that will pay for itself in the long run.

3

The problem is, the house system was sized to cool teh house, not the extra 4-500 sq foot (or maybe more) of the garage. Those through the wall units are very efficient and made just for things like this. Many heat as well as cool, if heat is needed. Plus by having a seperate system, when you aren’t there you can keep it set to just cool enough to keep the trains comfortable, not you, the drop the temperature when it’s time to go out there and work or run trains.

–Randy

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My neighbor had a general contractor convert his garage to a spare room. He also had the contractor add attic ducting from the existing central heat/AC system out to the spare room. The amount of heat and AC that reaches the spare room is sparse. He suspects that his heat/AC unit doesn’t have the capacity to adequately heat and cool the additonal space or maybe ducting design. Consulting an Heating/AC professional before adding ducting would be prudent.

regards, Peter

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It could be a lack of capacity. Or it could just be where the thermostat is located. For example, our house has the thermostat in the south facing living room. In the winter that room heats up from the sun, the thermostat thinks that it is satisfied, and the family room at the back of the house is cold.

If it were me, I’d opt for the separate unit that keeps the new train area at some reasonable temperature. I’d not want to be heating/cooling an entire house to be comfortable in one room.

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GACK!

You got more issues than can be answered here!

Now you are dealing with building codes and a lot of other things. I do not think that a duct between the house and a garage would be legal because of Fire Code issues, and the posibility of CO from propigating back into the house. Frequently a garage is little more than an “attached shed” and it blocked off from the house by fire doors and fire walls. Diferent kinds of insulation obtain between the house and garage as well as between the house proper and the roof as compared to the difference between the garage and the roof.

LION would find out more about the construction of your house, how it complies with codes, and how would compliance would be affected by modifications to the garage. A building contractor might need to be consulted, or perhaps a consulatition with a local archetech or engineer is needed.

ROAR

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I concur with LION. This is a major building code issue, which is based upon a safety issue. I confronted the problem when I had my current house built and I considered AC for the garage to allow working more out there in the summer. Even if you do it yourself someone will eventually have to deal with those issues when the house is sold - or before that if the safety problems turn very real.

Air systems for the garage almost certainly have to be completely distinct from that of the living area of the home. The primary concern is that of vehicle exhaust gasses infiltrating the home through such a joined system. One could install a completely separate cooling unit for the garage alone and then likely be okay. The safety of your home & family trumps comfort, even if it is comfort for modeling. Check with a professional.

Bill

8

The LION brings up a very good point that I hadn’t even considered. I withdraw my suggestion that you use the house heating/cooling to heat the garage. Even if the building codes where you are allow it, it’s a bad idea.

Go with a separate unit (or units) for heat and AC.

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Good point by LION on the code issue, but…

Conversion of the space into living space should obviate the code problem. Done all the time. Garage door has to go, of course, replaced with windows and a walkthrough, whatever (maybe just a blank wall, since there will be a layout on the other side[;)]). So long as it’s no longer a garage, it’s OK to punch through a no longer needed firewall. Check with your city inspector first, but I’m pretty sure that will work out.

As for the house’s existing unit…it all depends on whether its rated capacity is sufficient. Depending on who designed and spec-ed the original install, it may or may not have the capacity. From there, it depends. If enough capacity, then use it, as it’ll likely be more efficient in using energy than an add-on type unit.

If not enough capacity, then it depends on how old the house unit is. If over ten years old, it may be better to simply buy a new, more efficient and higher capacity unit and do it right. There may also be tax benefits to that which you will not be able to claim with an add-on. If the house unit is efficient, but not high enough capacity, then the add-on may, at last, be the way to go.

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Howdy, Nevin,

Since you and I are at opposite ends of the same valley, my experience may be helpful.

First - check with your code people (Henderson may be different from North Las Vegas, so it’s best to go to the source.) My garage has a gas hot water heater in residence, so I can’t close the outside vents. I’m thinking seriously of walling off that corner, heater, vents and all, and completely insulating the rest of the garage. Then it’ll just be a matter of adding a through-the-wall A/C unit of adequate size. Note that, if I do this in North Las Vegas, I WILL require code compliance, a building permit and all required inspections. (In rural Tennessee, I wouldn’t.)

While you’re at it, you might want to consider upgrading electrical service to the garage. Mine (a double) only had one wall outlet, in a particularly useless location, plus the outlet in the ceiling for the garage door opener that isn’t there. I power the layout and a string of convenience outlets from the latter. The former (on the only wall not bordered by benchwork) is available if I ever bring in a mini-fridge, a fan or a heater.

Whatever you decide to do, I strongly suggest that you do it before installing any benchwork.

Chuck (Clark County resident modeling Central Japan in September, 1964 - health permitting)

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Definitely check fo code requirements.

If all is allowed, go for fully insulating the area, overhead and all walls.

I’d go with a through the wall AC unit. The nice thing about them is in cold weather you can either take it out and make an insulated plug for the hole. You can also purchase kits to seal them.

For heating there are some very effecient wall mounted propane heaters.

As long as your bench work is reasonably high above the floor, you should be able to put both units under the bench on an outside wall.

Good luck,

Richard

12

I don’t have my layout in our attached 2-car garage but it is insulated including doors) and I had it built with a 220v outlet and a wall hole that a sizeable wall unit (A/C and heat) fit into. It gets pretty warm here in summer (over 100) and seldom below freezing in winter. I bought a quality Freidrich unit and it does a good job of cooling and heating when I want to work out there in hot or cold weather. I use a box fan to help circulate the air in the large space. It is surely not rael efficient but I don’t run it that often to have justified anotheer approach. It may not quite get to perfect temp but it gets it to an acceptable point.

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Was thinking of using portable LG air conditioners that our Home Depot sells here in Phoenix sells. Plus they are a lot cheaper than portable evap coolers ($700-900) and no worry about too much humidity. [:D]

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I have a very large attached garage and shop that I use for car restorations. It had a big window unit to cool it off but was marginal during the hot Georgia summers, and there was no heat. I replaced it a couple of years ago with a split system like you mention. When I priced them I discovered that once you get to a certain size then there is not much additional cost to going bigger, so I didn’t play- I put a 3 ton unit in to make sure it would cool off fast. And it also has a reversing valve so it heats during winter. Since the compressor is outside it is very quiet. Also good split systems do not cycle on and off like most window units, instead the blower and compressor speed up and slow down depending on the load. Bottom line- it works great and no regrets.

The bigger split systems run off 220V. I already had a 50A 220V service panel in the garage for the shop, so it was not a problem for me. If your garage is not that large then you could do with a much smaller unit than I bought though. And the 110V systems are probably more efficient than a window unit (definitely quieter).

Split systems must be charged with coolant which requires an AC service technician. I bought mine off the internet and did the installation myself. And I had an AC technician friend who was willing to check all the tubing connections and charge it with coolant. The cost was less than half what it would be to purchase from a local AC service but you have to know what you are doing. Not at all like installing a window unit.

Mitsubishi has the name here in the US but there are dozens of suppliers. I’ve done a lot of business travel to Asia and the split systems are the “standard” there, even for big-city high rise apartments. And there are a whole lot more manufacturers than Mitsubishi. The technology is very well-established even though it is not that common in the US.

15

Nevin,

It seems hobbyguy has the best answer to your Q.

You asked for anyone having experience with the split systems, and got a lot of “code” restrictions/approval/denial to look into.

It IS worth noting that One should always check on local building codes for ANY change to a house or building {and see if permits are required},wise advice.

I personally have 3 window type A/cs from 5,600 BTU to 12,500 BTUs to cool off this tin can {trailer with metal siding and roof} I call home. I do have a room with a layout in it with a window A/C in there. I don’t specifically have the Mitsubishi or other similar system, though.

It IS worth noting that if the garage is NOT insulated or finished off, you might actaully want to do that first.

Second, you don’t mention a window so i assume there isn’t one. So the window unit is out?

IF, and I sincerely mean IF, I were doing it , after insulating and finishing off a space, I could now choose the split system! Takes up little room by the looks of them on TV shows. I would definitely get teh one with heating as an option too.

OR, you could get yourself a small furnace with A/C unit in it to do just the garage, whichever is cheaper and cost effective to operate between a minifurnace an the split system.

I looked at a house where they had a spare small furnace with A/c coils in the garage { a big 3 car one} with an open directed plenum “vent” to heat/cool the garge {for working on race cars apparently}.

That is an alternative perhaps worth considering if the split system is too expensive and a window unit not an option.

Good luck and happy tracking to you!

[8-|]

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Oh No! Another problem. First you have to rexamine the overhead insulation, and bring that up to the same standard as the rest of the house. As an unheated space, most builders do not apply the same insulation to the attic as they would over a heated space.

Once you convert a garage into a “living space” you have, well added living space to your house. This will reflect in a higher valuation for your house, and of course a higer tax rate.

Putting a window airconditioner or a space heater in a garage is one thing, converting it into living space is quite another. The building inspectors and the taxman will be there with their palms out.

ROAR

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LION,

That’s true, but there’s really no zero cost option here. It’s just part of the planning for a project like this. Improving a garage to living space is gonna cost you, first of all for the materials to bring it up to whatever code applies. Yes, there may be tax issues involved, as there almost always are with any improvement to property. For instance, there are likely some jusrisdictions where, once you hang an air conditioner in it, they’ll start taxing you on it being living space, WITHOUT any further improvements.

That’s one reason I brought up the fact there may be tax benefits to replacing a whole house system that could make that the most cost effective solution, as well as to check with the relevant local gov’t authorities. You want to figure this stuff out before you start on a project yourself or, even worse, sign a contract to have someone else do the work. It’s not just the cost of materials and whether or not you can do the labor – which can be the biggest cost saving factor of all.

One thing’s for sure. If you make marginal improvements to a space, then build a layout in it, you’ll likely regret not just doing it right to begin with 10 years from now.

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We are lucky to live in a relatively rural area so codes are not rigorously enforced and tax assessment is cursory at best. Everyone’s situation is different though. Regardless, you still want to do it right.

I checked and still have the links to the on-line sites that I used. Looking back I see that I actually purchased a 2 ton unit, not 3 ton. But still a whole bunch of cooling for the area. My reasoning was that the garage is not well insulated but I am only out there when I have a car project going on. If I were using it for a MRR then I would plan to keep the unit running to prevent temperature swings that could affect trackwork. So adding insulation would make sense. And then you don’t need near as much cooling capacity.

Here are the links. If seriously considering a split system then I recommend researching what is out there even if you get a contractor to purchase and install for you. And if considering installing yourself then definitely do the research because it is not that simple. I spent about $1500 for my system and it has heating, automatically varies speed, thermostatic control, and a bunch of features that I don’t even use.

http://www.split-air-conditioners.com/24000-btu-ductless-air-conditioners-s/1669.htm

http://www.split-air-conditioners.com/YMGI-18000-btu-split-air-conditioner-SEER-13-p/wmms-18k-32b-m3.htm

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Thank you everyone, this has been a very helpful thread. Since I live in a neighborhood with lots of codes and covenants and my profession is such that I might be moving on at some point (hence the semi-portable nature of my layout), I don’t plan on converting the space in to living space. I want to keep such that I can convert it back as a garage someday. Fortunately all the other garage things like water heaters are in the 2 car garage. The fire codes probably preclude hooking it up to the house AC system. When we bought the house, there was a dog door cut into the door between the house and this garage and the house inspector made the seller remove it.

Looking at a small portable AC system or a two part system independent system appears to be the best route. There is a second dog door between the garage and the side of the house. That would be pretty easy to run the connections between the two parts of the AC. A small window AC might fit into the dog door (it must have been a pretty big dog!)

Thanks for all of the help. - Nevin

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Nevin,

That sounds like a plan that suits your needs. Good luck with things![:D]