garage heating supply vent

Hello fellow Innernachians
I was just wondering what you would say about these two items in the garage aprox. 3 feet from each other. A gas fired furnace supply heat vent in the garage and a man made hole in the water heater flue.

Cap the end of flue in second picture.

Here if a furance is in a garage it must be installed 18" above the Floor.

I believe ony the source of ignition needs to be 18" above the floor.

Is that furnace a downflow?

Recommend a qualified HVAC technician for further investigation and or repair including installation of combustible fuel appliance(s) 18" above the floor in a garage and repair/replacement of the vent connector.

How old is the furnace? looks a little rusty. How does the burners/heat exchanger look? The register installed in the house air fan housing may reduce the air flow to the other registers through out the home.

I know of no requirements for a furnace to be on an 18" stand in a garage. I think someone is confusing the water heater requirement with the furnace. There must be 18" from the floor to the ignition source, however.

The ductwork is a different issue. You cannot have openings to the ductwork system in the garage and the ductwork, itself, needs to have “mechanical protection” from vehicles.

Thanks John that was what i was looking for. The other problem that i see is that since the water heater flue has two openings and there is a supply duct in the garage that it could possibly postive pressure the flue and cause back drafting on the water heater flue at the draft hood.
And also that you cannot have a supply duct in a garage for safety reasons.
the house was a 2005 age and the water heater and the furnace were installed high enough to be above the 18 inch rule. Any ignition source should be up above 18" inches in the garage. the furnace is a downdraft unit.

Gases will not vent correctly if you have two openings.

Furnace lowest potential source of ignition needs to be 18 inches above the floor, which it appears to be (same rule for water heaters). Ducts inside or leading to the garage need to be metal, at least 26 ga. Not sure what you have there???

Positive pressure does not cause back drafting of appliances, negative pressure does. I believe that the opening on the water heater vent should be capped (but not positive).

This is true. . .

Agreed. Should be blocked off.

thanks for the feedback guys.

I hope the following information can be of some help to you.

2009 International Residential Code
M1601.6 Independent garage HVAC systems.
Furnaces and air-handling systems that supply air to living spaces shall not supply air to or return air from a garage.

2009 International Residential Code
Part V.-Mechanical
Chapter 16 Duct Systems


M1602.1 Return air.
Return air shall be taken from inside the dwelling . Dilution of return air with outdoor air shall be permitted.

M1602.2 Prohibited sources.
Outdoor and return air for a forced-air heating or cooling system shall not be taken from the following locations:

[FONT=Arial]1. [/FONT]Closer than 10 feet (3048 mm) to an appliance vent outlet, a vent opening from a plumbing drainage system or the discharge outlet of an exhaust fan, unless the outlet is 3 feet (914 mm) above the outside air inlet.

[FONT=Arial]2. [/FONT]Where flammable vapors are present; or where located less than 10 feet (3048 mm) above the surface of any abutting public way or driveway; or where located at grade level by a sidewalk, street, alley or driveway.

[FONT=Arial]3. [/FONT]A room or space, the volume of which is less than 25 percent of the entire volume served by the system. Where connected by a permanent opening having an area sized in accordance with ACCA Manual D, adjoining rooms or spaces shall be considered as a single room or space for the purpose of determining the volume of the rooms or spaces.

Exception: The minimum volume requirement shall not apply where the amount of return air taken from a room or space is less than or equal to the amount of supply air delivered to the room or space.

[FONT=Arial]4. [/FONT]A closet, bathroom, toilet room, kitchen, garage, mechanical room, boiler room, furnace room, unconditioned attic or other dwelling unit .

[FONT=Arial]5. [/FONT]A room or space containing a fuel-burning appliance where such room or space serves as the sole source of return air.

Needless to say that the “man made hole” in the water heater flue is discharging poisonous fumes into the garage and this is a dangerous situation/safety hazard that should be called out immediately!


Thanks Frank I did call it out as a major concern and the realitor thanked me. Thanks for the info i will add it to my book of backups. So if challenged i have backup as to why i wrote it up.

Be sure your jurisdiction has adopted the 2009 IRC before you quote from it.

Thanks Mr. Bushart I never quote from a code or any source that is a legel source. I just recommend that it is for the reason that it is. If for some reason someone wants a reason than i will show them why I am calling this out for further evaluation because this is the standard or code. But i am not the authority that states that this is the law or reason. I am only the person that noticed this and it should be further evalutated because of this reason. I am not the law or code enforcer of anything. And my inspection is a snapshot in time that is recommendations that will help them out based on the reason for the item.
but thanks for the input

Frank thanks for the latest code I found it helpful. :smiley:

I do not know about anyone else, but I also recommend that clients install CO Detectors if they have fuel burning appliances.:smiley:

Check out Chapter 17 at this Oregon website;
**2008 Oregon Residential Specialty Chapters **

You are more than welcome! One of the things I enjoy about this bulletin board is that if you are not quite sure about something sooner or later someone will come up with an answer.

I think your recommendation about a CO detector is a good one and I will keep that in mind!:stuck_out_tongue: