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Oil furnace smell

Pim Member Posts: 4
26 year old oil furnace, cleaned yearly. This year, service man spilled oil when he changed filter. Since then, when furnace starts, there is an oil smell, especially from one vent. I had the service people back out and appears not to be anything wrong with furnace. They added sweetener, but the oil smell still lingers. Any suggestions are greatly appreciated. 


  • Jamie Hall
    Jamie Hall Member Posts: 23,272
    Hot air furnace? If so, you -- or they -- are going to have to find the spilled oil. All of it. Even what's soaked into the concrete or whatever. And get rid of it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    Probably dripped into the cabinet and getting sucked into your air stream.
    Another possibility is when they cleaned it they didn't re-install the cleanout gaskets properly, or they needed to be replaced, and now your combustion gas is mixing with your conditioned air.
  • Pim
    Pim Member Posts: 4
    Yes, hot air furnace
  • Pim
    Pim Member Posts: 4
     Here is what was on the invoice
    Completion Notes: Made a call for heat at t-stat and could smell oil coming out of kitchen vent. Used analyzer to check furnace operation and readings were CO- 36 O2- 11.5 CO2- 7.0 EFC- 78.5. Sprayed sweet air in R/A drop and some also by oil tank due to valve had some oil on it. Furnace operating properly and advised customer to allow several days for sweet air to dissipate.
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,541
    Way too much air if those numbers are correct.
    To learn more about this professional, click here to visit their ad in Find A Contractor.
    rick in Alaska
  • SuperTech
    SuperTech Member Posts: 2,152
    Way too much O2 and CO. Could easily be a hole in the heat exchanger thats causing your odor. Spraying sweet air in the duct isn't a replacement for cleaning up any spilled oil,  if any was actually found. I'd be very concerned about the horrible combustion analysis numbers.  I would never leave an oil furnace running like that, they shouldn't have left without figuring out why its not running correctly.  Was a smoke test performed? Did anyone check for CO in the house?
    EBEBRATT-Ed Member Posts: 15,512
    Could be a bad furnace heat exchanger. 26 years old and the expected life expectancy of a furnace is around 20.

    Have them check for Co in the house and at the hot air vents. If there is no co, the smell will probably dissipate.

    Have them adjust the burner your combustion numbers are not great
  • Pim
    Pim Member Posts: 4
    Will do, thank you
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,818
    You should not discount the cracked heat exchange possibility, however, If there was a fuel spill, no matter how small, that odor will linger for many, many weeks.

    There is a simple way to get rid of an oil odor that can't be cleaned away. Get a spray bottle and fill it with vinegar. After cleaning and drying away as much of the spilled oil as possible, generously spray the area of the spill with the vinegar. Do this 2 or 3 times a day until the odor is no longer noticeable.

    There is also a product made by the same company as the SweetAir spray. It comes in an absorbent powder. I have used this successfully to solve your problem. This is to reduce or eliminate the odor of raw, unburnt fuel. This will not work on exhaust odor from combustion. In order to get customers to describe the odor properly, I would ask them if the odor was more like the exhaust from a bus or truck (deisel exhaust) or more like a gas station odor where the vapor is exiting the fuel tank when filling from the pump.

    The latter is raw fuel, the former is combustion exhaust and that can contain carbon monoxide CO which is dangerous and needs to be addressed.

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics