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Hot air furnace, intake in non-conditioned basement space? Anyone know if there are regulations?

vilord
vilord Member Posts: 48
A friend in an apartment was complaining that the mildewy basement air was coming up through the vents into her apartment. It's a rental apartment, but I recommended sealing up any air gaps on the return air duct, and she says 'oh, there isn't one, there's just a filter on the side of the furnace that draws in basement air'.

Does anyone know if this is a common thing? Or if there are any regulations about it? It seems like a great way to give all the tenants allergic reactions, mold-related health problems, and possible also a great way to spread radon and CO through the conditioned spaces in the house, not to mention that it's really hard to push hot air into the conditioned space if nothing is pulling back out the return air...

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,822
    edited December 2020
    All the applicable codes that I am aware of indicating that the combustion air for a furnace can cot come from the same space as the return air in cases where the furnace uses combustion air from an unconfined space.

    So that means if the heat source is an oil or gas-fired furnace, and the combustion air is not ducted in from the outdoors, then the furnace needs a ducted return from the conditioned space to the return air opening on the furnace.

    A picture of the furnace would help in confirming that the combustion air is coming from the same space as the blower intake air.

    Furthermore, the untreated air from the crawlspace does represent a health issue. I would contact the landlord and inform them of the issue. The landlord may not be aware there is a problem with the situation.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • vilord
    vilord Member Posts: 48
    edited December 2020
    Yep, I definitely recommended contacting the landlord because of the health concerns. Good point on the combined combustion air source plus return air source both being the same basement, that is very likely given the age of the systems involved.
    I'll see if I can get her to shoot a picture for me.

    Thanks!
  • bburd
    bburd Member Posts: 912
    edited December 2020
    I saw this condition once in a 19th century rowhouse that was for sale in Massachusetts. A new oil fired forced air furnace had recently been installed in the basement and connected to the existing supply ducts, but all the return air was taken from a big grill on the side of the furnace. There appeared to be no provision for return air to flow from the upper floors back to the basement other than leaving the (solid) basement door open. The burner drew its combustion air from the basement, with no fresh air intake. 

    If someone had closed the basement door, the burner exhaust fumes would likely have been pulled back into the room by the negative air pressure from the return intake, causing sooting, producing carbon monoxide and distributing all of this throughout the house. At least with an oil burner the occupants would smell it; with a gas burner they would smell nothing, and might be killed by the carbon monoxide.

    I told the real estate agent how dangerous this was, and said that I couldn’t understand how the work had passed inspection. I don’t know if anything was ever done about it.



    Bburd
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,516
    @EdTheHeaterMan said

    "All the applicable codes that I am aware of indicating that the combustion air for a furnace can cot come from the same space as the return air in cases where the furnace uses combustion air from an unconfined space

    And he is correct
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,822

    @EdTheHeaterMan said

    "All the applicable codes that I am aware of indicating that the combustion air for a furnace can cot come from the same space as the return air in cases where the furnace uses combustion air from an unconfined space

    And he is correct

    Goes to show you that 2 Eds are better than one.

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    mattmia2Canucker
  • mattmia2
    mattmia2 Member Posts: 9,625
    I think this was not unusual in the first half of the 20th century or so although certainly not allowed now.