Central AC garage

[LoneGunman]

Is it against code to add a garage to your central HVAC system? I remember reading somewhere it was, can't remember where. I'm thinking about putting a supply in my attached two car. The biggest issue I can think of is carbon monoxide but no vehicles will be parked in the garage. Haven't gotten around to seeing if the system can handle it.

Another question, the house has a strange layout, off the attached garage is a one room addition, it has a supply, the only way into the room is to go through the garage. Usually with only one return the doors are cut a little short on the bottom for air to circulate (I guess?) but being the door leads to an uncooled area I don't believe the supply is doing much, the room is pretty uncomfortable. I was thinking about replacing the door and weatherstripping it. One wall of this room is back to back with the family room, I'm thinking about cutting in a 1'x1' hole and adding a loover to each side. This should even things out, no?

 

[mrb]

cant do it due to fire rated wall.

 

[hobie1dog]

If you install a fire rated damper in the wall, it should then meet local codes. This would have a temperature sensitive fire link that will break(usually at 160 F) and close the damper(like a curtain style-only vertical)

But to get rid of the heat in the summer, a return air duct would also be needing to get the hot air back to the A/C coil, and another fire damper too.

 

[Falcon67]

Two things come to mind - 1) that's a big load to add to your AC unit and unless it is already oversized it may not be able to handle the extra heat and 2) since when do builders put in fire rated walls between the garage and the house? I snoop around construction all the time - love to see framing. I never see any fire rated or double walled sheetrock used in houses around here.

 

[ket-tek]

In my area 5/8" fire rated sheetrock is required all walls in an attached garage since 2003, before that they just required 1/2" sheetrock on the ceiling and any common walls with the house.

They do not allow hvac to be shared between the house or garage in any layout. You can install a standalone system in the garage though.

In my last two homes both with 400ish sqft garages I just added a supply duct off the house system. (against all advice from everyone I asked about it.) and it actually worked quite well! (no return duct of any type of course) The walls were sheetrocked and insulated and they had insulated doors. It maintained a bearable temp in the winter and summer as long as you didn't open the garage door, or it would take a few hours to recoupe.

I never had any smells or noticable fumes in the house (I never ran vehicle in the garage either), and the houses seemed to have no ill effect from the loss of air. In the spring and fall I would just close the louvers as it wasn't really needed.

When I sold the last house, the home inspector for the buyers busted me up about it, he said when the system is off that carbon monoxide could back feed into the house. So I removed it for the new owners.

My new garage I went with a mini-split as it is affordable and easy to install. And have better control of the temp.


And adding the louver from that extra room to the house may help, as your pushing air into the room but not exchanging any of the old. But I'm not an AC guy so I'm not for sure, hence me just adding illegal ducts to my garage, that could have killed me!?

Google 'transfer ducts' or 'bypass grill' as that is the concept your talking about.