Ontario: No return air in basement

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Posted by: from Toronto
6/7/2021 at 2:33:46 PM

Hi there!

I'm looking at a beautiful, brand new basement apartment. However, I've noticed there are no return air vents anywhere. Unless there's one in the furnace room, which is kept locked. But I don't think there should be one there anyway.

I owned my own home for many years and know what to look for, but this has me stumped. And this from the building code doesn't help. "(14) In a house containing two dwelling units, return-air from one dwelling unit may be recirculated to the other dwelling unit, provided a duct-type smoke detector is installed in the supply or return air duct system serving the entire house which would turn off the fuel supply and electrical power to the heating system upon activation of such detector."

The doors to each room have enough space for airflow beneath. But the question, is it a code violation to have no return air in the basemen?


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Date/Time6/7/2021 at 4:22:46 PM

To answer your question directly you would have to speak to your local building inspector in your area. Each company that handles mechanical furnaces and ducting as what you are referring to needs licensed paperwork, we keep heat and cool in but the actual devices to heat and cool require another certification on their installs. Submit it to local building authorities and have them inspected, if this basement suite is legal. Also it would not be allowed to have one furnace servicing two suites for more than one reason. I hope this helps.

All Well

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Ian in Edmonton
Date/Time6/11/2021 at 3:12:13 PM

It's interesting that in Ontario apparently it's allowed to heat a home with a secondary suite with a single furnace. Another poster attached this link regarding the requirements .

The following articles are found in both the Alberta and National Building Codes: 'Air duct distribution systems serving one of the dwelling units in a house with a secondary suite shall not be directly interconnected with other parts of the house.' 'In houses that contain a secondary suite heating system ventilation need not be provided for exits, public corridors and ancillary spaces that are not within the dwelling unit.'

These two articles suggest that there is to be no mixing of air between suites; more important now that pot is legal. I've had roommates in my home complain about a smoke odor when nobody in the house smokes and nobody else smells anything. Certainly it's unacceptable to have supply to a suite with no return. (Note: return air also cannot be taken from a furnace room.)

Ian Derksen

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