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Burning Smell from Steam Radiator

We recently moved into a Victorian era home with a single pipe steam radiator system. The house was owned by the same family for many years, then purchased by an architect who did some serious renovations on the first floor before selling a little over a year later. Because she took out a wall with radiator plumbing on the lower level, she removed a radiator in one of the bedrooms and ran pipe to a different unit that would fit under the window in that room. The radiator definitely isn’t new, but it’s not the one that had previously been in that space and I’m not sure where she got it. 

This radiator smells like burning plastic or rubber every time the system runs for a significant period of time, even after cleaning. It was initially not heating well this fall so I replaced the air vent. Now that it’s fully heating up, the smell is more significant. I’ve noticed that there are a few areas where the white paint has a faint brownish tinge to it, like maybe the paint itself is burning. I can’t find any information about the wrong paint burning or causing fumes after the initial burn off, so I’m not sure if this could be a factor. Last night I also noticed that a portion of the paint on the base had a spongy feel to it, so I pulled away a small piece revealing a tremendous amount of very powdery rust. 

My questions are:
Could improper paint be causing ongoing off gassing? If so, how can I fix this while the system is in use?
Is this level of rust problematic, and what can be done about it?

Thanks in advance for your thoughts. 


  • Jamie Hall
    Jamie Hall Member Posts: 23,326
    I wonder what it was painted with? Yes, the wrong paint choice can cause continued outgassing and smells. Older latex paints are particularly problematic that way (not the new acrylics -- they're fine).

    The rust patches indicate that a sloppy job was done prepping the surface for paint.

    Difficult -- but not impossible -- to fix while the system is in use. The problem being that if the radiator was painted all over when it wasn't installed, it's hard to get to all the parts --which is what is needed. You need at the very least to scrape and wire brush it very thoroughly to get any loose paint off -- you can be as much of a gorilla as you like; it's an excellent job for when you want to take out your frustrations on something. Then you can paint the whole thing with a shellac based odour stopping primer, and then a quality modern acrylic.

    Better if you can wait until the radiator can be taken out of service. Then you can take it to be sandblasted and either powder coated or properly repainted.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • delcrossv
    delcrossv Member Posts: 742
    Having just done a bunch, that sure seems like bad paint. I've had good luck with high temp black . But in any event it needs the old paint and rust removed- either sandblasting like Mr. Hall recommends or a lot of hand work with wire wheels and wire brushes.
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • ethicalpaul
    ethicalpaul Member Posts: 5,704
    I think that high-temp paint is quite overkill. 200 degrees isn't high temp. The modern acrylic paints do a great job and don't offgas very much at all.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,304
    Hi, I'd be tempted to take a small pile of paint chips from the radiator and heat them up in an old pot. Then smell what fumes come from that to see if the paint is actually the source of the smell you're getting. It looks like it could be an epoxy paint, which might be the problem. That info can guide your next steps.

    Yours, Larry
  • dopey27177
    dopey27177 Member Posts: 887
    edited November 2021
    As was said remove the radiator and sand blast it. I like rustoleum high temp paint the same stuff they paint car engines with. A can of spray paint cost about $6.00 and will more than cover one radiator.