Supply Vents in Garage

Recently inspected a townhome with drive under garage and finished basement. Two HVAC supply vents were installed in the garage (one directly above a gas water heater flue. I stated the normal safety concerns and recommended a licensed HVAC contractor inspect and correct as needed. Here is what the licensed contractor put in writing on the invoice:

"System is working properly at this time. Ducts in garage are supply vents and have been inplace since time of install. There is no code stating that you can not have supply vents in a garage. To seal the vents off could cause the downstairs Zone to be out of balance and could cause problems in the system operation."

My thoughts are do you want to live with a potential safety hazard or “live” with a balanced sytem.

What are your thoughts?

2006 IRC states:

Interpret as you see fit.

I would send a “copy & paste” of this persons response and the code section side by side to the owner/buyer of this property. The UBC and IRC both prohibit openings within the garage.

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This is one of the problems that comes with advising a client to have a “contractor” come and “inspect” something that is wrong and dangerous.

Amend your report and instead of recommending a contractor to “inspect”, recommend that the unsafe condition be corrected by a qualified contractor.

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You are asking for thought so here are mine. He is correct no code against supply duct in the garage. He was more than likely the contractor that installed it do you suspect he might be a little on the biased side.

More than likely would require re-balancing the system so what do it anyway. Only a meat head would install a supply vent over the top of the flue exhaust of a water heater not good engineering practice. I know of no code that requires the exact location of the supply vent but the common sense rule should apply. That is my thoughts and I am sticking to them:D:D

Just made a general comment for the post but my Report comment does recommend that the conditon be corrected for safety (all underlined) by a licensed HVAC contractor.

Anyone mention the word “Damper”

Re-read post no.2. :slight_smile:

I have a supply vent in my garage. It keeps the dog cool in the summer and melts the snow off of the vehicles in the winter.;):shock:

From an inspector’s perspective, it has little to do with furnace and water heater vents or smoke coming from a fire. Here’s why it matters:

People have to be protected from their technology and their ignorance about it.

It’s not only dumb but it is against code. What prevents any fumes in the garage from working their way into the duct system and in to the home. The home is usually under a slight negative pressure due to stack effect anyways so now you have a direct connection to the garage. Having a supply to an area that can’t return will cause an even larger negative pressure in the home when the FAU in on.

IRC Section M1601.6- HVAC systems that supply air to the garage shall not supply or obtain air from any other space but the garage. HVAC systems that supply air to the living space shall not supply or obtain air from any other space but the living space.


I repeat…anyone mention Dampers…yesh.

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Building standards require that all ducts in the garage and ducts penetrating the firewall be equipped with fire-dampers or constructed of a minimum of No. 26 gauge sheet steel or other approved material and shall have no openings in the garage. This condition compromises the garage firewall system.

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From that thread.

*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 sheet steel or other approved material *and shall have no openings into the garage.

Also I believe this is referring to duct pipe passing through a garage not a supply or return vent.

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That is what I had going into a garage last May and notice the auto-damper that Chris helped me figure out.

From a recent Inspection…
HVAC supply and return to garage along with recessed lighting in the ceiling…

Home was the Builder Sample Home with the site office in the garage. Changes were not made after the patio doors were removed and the space was converted back to Garage…

Thermostatically controlled dampers are not the same as fire/smoke dampers.

Even with fire/smoke dampers, model codes do not allow for openings within the garage.

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Here’s a pic of one of the garage vents… great location :roll:

garage vent.jpg

I see the TPRV is following it as well…incredible…:shock:

I recall a few people told me it was OK with the damper with nobody casting a descending vote.

Proper documentation of course would help.:wink: