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HVAC in a garage

Sifu

Sifu

SAWHORSE
Joined
Sep 3, 2011
Messages
3,318
Codes do not permit duct openings in a residential attached garage, for obvious reasons. I ran across one yesterday where it appears that the contractor is placing an air handler in a garage under living space. My first reaction is -not permitted- however as I thought about it I figured the unit is sealed, the duct is hard piped and sealed so maybe it is permitted. I go to the 2006 IRC code & commentary and it contains a picture of a "furnace" in a garage which is apparently permitted. Now I am stumped. I might be able to see an air handler, but a "furnace". The word "furnace" to me implies combustion air, and with no indication of the combustion air source I would think it could be considered an opening into the system, possibly letting fumes, gases etc not only into the spaces above but into the combustion chamber as well. So I ask the experts.......What types of units would be permitted in a garage like this? One thing to keep in mind, my jurisdiction has not adopted any mechanical codes, I am limited to the IRC in this case unless I see a real safety concern.
 
To clarify, my jurisdiction has only adopted the "building" chapters of the IRC, excluding all others......I know crazy.
 
So long as the furnace draws all its air from the outside, and all ignition sources are located 18" above the floor, and the equipment is protected from impact it is allowed.
 
What types of units would be permitted in a garage like this?
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Anything that is not a solid fuel fired unit. The leakage around a garage door and the cubic volume of a double car garage should provide an adquate supply of combustion air to any "B" vented unit. We have encouraged CO detectors in homes with attached garages for years especially if a HVAC unit is installed in the garage. In this climate to many people like to warm up the car while the car is still in the garage
 
Agree with my esteemed colleages and add.....

R309.1.1 Duct penetration.

Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum No. 26 gage (0.48 mm) sheet steel or other approved material and shall have no openings into the garage.
 
mtlogcabin said:
Anything that is not a solid fuel fired unit. The leakage around a garage door and the cubic volume of a double car garage should provide an adquate supply of combustion air to any "B" vented unit. We have encouraged CO detectors in homes with attached garages for years especially if a HVAC unit is installed in the garage. In this climate to many people like to warm up the car while the car is still in the garage
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i always thought the same thing about adequate combustion air supply thru infiltration. Recent testing has shown in addition to the infiltration air we had to open a 4040 window about 6 " to 8" to get the required air to the fuel burning appliance. the person performing the test said the code under estimated the combustion air requirements and unusually tight construction has added to the problem. more to come.
 
In my area, combustion air vents are installed in the exterior wall to allow for adequate air volumes. A standard 80K unit with water heater will not have enough combustion air from a 21' x 22' x8' garage if I calculated the requirements properly. What do you suppose the homeowner covers up first when they move in?
 
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Robert S.,

I too concur with the esteemed forum members on your question.

If the combustion air and exhausted air is from, and directed to

the outdoors, elevate the ignition source 18" and your good to

go.....This scenario is exactly like a fully sealed attic space with

no soffit or ridge venting.

Now, ...about your AHJ only adopting "the building chapters".

What's up with that? :confused:

: : : : : : :
 
304.5.1 Standard method.

The minimum required volume shall be 50 cubic feet per 1,000 Btu/h (4.8 m3/kW) of the appliance input rating.

Recent testing has shown in addition to the infiltration air we had to open a 4040 window about 6 " to 8" to get the required air to the fuel burning appliance
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In a garage?

Never seen a garage yet that would classify as tight construction.

A 16 ft x 7 ft garage door with a .125 inch gap will provide 24 sq inches of openable area
 
Clarification needed!

Ducts in garages shall be constructed of No. 26 gage sheet metal. Then therm-o-pan would not be allowed even if covered with 5/8" firerock. Yes

I'm being told you have to use FIRE RATED therm-o-pan which is not No. 26 gage metal.

www.thermopan.com.

pc1
 
It's your call

My 2 cents is where the duct is exposed it is required to be 26 gauge. If it is covered with sheetrock no matter what it is made of it is protected.
 
Everyone pretty much is saying what I believed to be the case but for a few clarifications: I also judged the fuel burning system to be permitted only if all combustion air is pulled from outside so my question is this, what does the "tightness" of the garage have to do with this? I think this is irrelavent anyway since I think it is only going to be an air handler.

As for the adoption....the jurisdiction I am in has adopted the least amount of code as humanly possible. Until very recently, they had zero code so it is a step in the right direction. I am told they will phase in other parts of the code as the "constituants" become more comfortable with it. For now we have no commercial code of any type unless the somewhat murky process of the SFM becomes involved, no mechanical code, no plumbing code and of course none of the other many lesser codes. None of the appendices and only chapters 1-11 of the 2006 IRC have so far been adopted. And believe me, considering the battles I am fighting, phasing in the rest is probably a good idea for my health. Politically, I probably won't be around long enough to see the adoption of any additional codes. Some of my bigggest detractors are in my own office and I certainly have no allies in this ordeal. What the heck though, if they are going to let me go I figure they will have to do it for doing my job as opposed to not doing it. The primary reason this thread was started was because this addition was built and I showed up to do the framing inspection and found that the builder had no plans to protect the living space above the garage, no plans to insulate it and had run all the ducts and plumbing tight to the bottom of the joists and had left the rough for what was going to be a system installed in the garage. I informed him of the protection issues but I am on a bit of a slippery slope with the mechanical stuff since I don't have a code to use. Of course now he will need to drop all his stuff to insulate and sheetrock. I am sure a call to the mayor is coming!
 
That's why a lot of us have "alias" names. You're more than like ly to be safe! If they don't have codes they sure ain't gonna read the forum! :)
 
Your "job" is more of education than code enforcement. Explain the benefits of what the code is trying to achieve in each situation. Have news articles and examples of tragedies that could have been avoided if the code was followed. There are plenty out there. Ask the board members here for examples, we have seen and read a lot. Get the fire service folks on your team especially for dealing with the politicians. I agree in a slow process for bringing codes to a jurisdiction I would have started with commercial first.

Pick your battles wisely and don't sweat the small stuff, Explain to them what is wrong and you expect it to be correct on the "next" job.

Life safety items stand firm.

Give them options, maybe let them drywall around the duct instead of lowering it
 
Kinda what I figured but was wondering if I shouldn't rename myself. Any idea if thats possible without creating a whole new identity? Going out to make more friends now!
 
This reads a little funny but I think that Tennessee mandates codes to be followed.

http://www.state.tn.us/sos/rules/0780/0780-02/0780-02-02.20081216.pdf

0780-02-02-.05 LOCAL ORDINANCES. Except as provided in Tenn. Code Ann. §68-18-101, no city,

county, town, municipal corporation, metropolitan government, or political subdivision of this State shall

adopt or enforce any ordinance prescribing less stringent standards of fire prevention, fire protection, or

building construction safety than those established hereunder.

Authority: T.C.A. §§58-2413, 68-17-113, 68-18-101, and Chapter 857, Public Acts of 1982.

Administrative History: Original rule filed July 17, 1982; effective August 26, 1982. Amendment filed

October 11, 1985; effective November 10, 1985.
 
Robert S said:
Kinda what I figured but was wondering if I shouldn't rename myself. Any idea if thats possible without creating a whole new identity? Going out to make more friends now!
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I bet that Jeff can do that for you!
 
I am trying, the education continues and believe me I do pick my battles. There are no "fire service" folks either. There is no FM, no inspections to speak of though, there is talk of it coming.....
 
Mule: Robert, What State are you in?

A state of worry, I suspect? Hang in there, this gang will help!

Change your name to Roberto S., they'll never figure it out!

BC1, see it's easy!
 
Pcinspector1 said:
Mule: Robert, What State are you in? A state of worry, I suspect? Hang in there, this gang will help!

Change your name to Roberto S., they'll never figure it out!

BC1, see it's easy!
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Been there done that!!! :) Hang in Roberto! It will get better! You eat the elephant one bite at a time.........eventually you've ate the whole thing!
 
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