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Two connected radiators (single pipe) with smell coming from connecting pipes

jjx Member Posts: 3
I bought a co-op apartment 14 years ago. In the living room there are two radiators on a single pipe system connected by two pipes:

I have never had an issue with these radiators until this winter. Two months ago the valve developed a leak, which damaged the ceiling of the apartment under mine. The building called a plumber, valve replaced, leak gone. However, once the ancient valve was replaced, the radiators started producing three to four times the heat they did in prior years. This triggered a noxious melting wax smell emanating from the pipes connecting the two radiators.

I have ruled out dead rodents (the cabinet is clean and there is no access for pests) and smell from the paint on the radiator enclosure (the smell is only from the connecting pipe area). There is no smell coming from the radiators themselves, so I also ruled out the radiator paint as the cause. There is also no smell when the radiator is cool to the touch.

I believe the smell is coming from the substance that seals the connecting pipes (particularly the upper connecting pipe, where I believe most of the smell is coming from). Am I right or could something else be the cause? More importantly, is there anything I can do to mitigate or remove the smell?

For those who are wondering about the metal coffee can in the photos, the previous owner of the apartment rigged a metal plate to cover the vent hole of the radiator connected to the valve to reduce the heat produced:

This does indeed reduce the heat in the radiator farthest from the valve (as I learned when
I temporarily removed it). I imagine the coffee can is there to catch any water that might leak from the vent, but none is currently leaking, nor has any leaked for at least 14 years.

For completion's sake, here is a picture of the new valve that was installed:

All help is very much appreciated.


  • CLamb
    CLamb Member Posts: 262
    The pipe dope on the connections could be removed with a stiff brush and wiping with a cloth or paper towel. I'm wondering if that odor is coming from the vent. Perhaps the boiler has had some chemical treatment added to it and that is what you are smelling.
  • mattmia2
    mattmia2 Member Posts: 9,475
    If they used pipe dope on the threads you can remove it by scrubbing with a rag soaked in paint thinner. That looks more like they used blue monster brand teflon tape. The pipe or the valve could have oil on it which you can also remover with paint thinner. Scrubbing with something like simple green after will remove the final traces. Be careful because the paint thinner is flammable.

    You can put a very slow vent on the radiator to slow down the heat. Some of the variable ones are still pretty fast at their lowest setting so you have to choose wisely.
  • mattmia2
    mattmia2 Member Posts: 9,475
    If the radiator on the left has the only feed and has a vent you could probably reduce the heat by closing both valves between the radiators too.
  • jjx
    jjx Member Posts: 3
    Thank you for your suggestions CLamb and mattmia2! Here's where I am (with additional questions):

    Is odor coming from the vent?

    I don't think so. I removed the plate covering the vent hole nearest the valve and taped it shut using Venture Tape. The smell remained. Additionally there is no smell where the second radiator's vent is located, nor any coming from the vents on the two other radiators in the apartment (all on the same boiler).

    Can you put a very slow vent on the radiator to slow down the heat?

    The boiler for the building I live in has been running continuously for many weeks and the super will not shut it off unless it is an emergency. (As such, I have my windows open to mitigate the heat and the smell.) I will replace both vents once the warmer weather arrives, but I cannot do so now.

    Can you reduce the heat by closing both valves between the radiators?

    The radiator on the left (closest to the valve) does have the only pipe connected to the steam feed and also has a vent (both radiators have vents). However, I am told these valves are very old (possibly dating back to the seventies) and I am worried if I attempt to close them they will break and water/steam will start spewing out. Also, wouldn't closing the valves while the heat is on be inadvisable (as I cannot shut off the heat)? Should the weather get warmer and the super decides to give the boiler a rest, how risky would it be to close the valves?

    Could you use a wire brush to remove the pipe dope?

    I could, but I've now read quite a few posts that say the pipe dope should not be giving off the odors I described (especially after so many years). So I took a napkin and rubbed off a good amount of the pipe dope onto it (the pipe dope was soft and came right off without effort). When I smelled the pipe dope on the napkin it was not the same melted wax smell coming from the pipes. I also noticed that the pipe dope is covering what looks like Blue Monster Teflon Tape. Here's a close-up of the top pipe's connections:

    And one of the bottom pipe's connections:

    Should I still attempt to clean the pipe dope off the pipes? Is there a good reason for a person putting pipe dope over the Teflon tape (perhaps because of another issue)? There is a non-flammable paint thinner I can use called Turpenoid to wipe the pipe dope off and avoid the use of a wire brush (so I do not rip up the Teflon tape). However, I'd rather first confirm the source of the smell, if I can, before I pursue this. Any ideas on other possible sources of the smell? Or other ways to reduce the heat in the radiator without turning the building's boiler off (both vents are now taped shut, but the heat is still at least three times what it was before the new valve was put in)? All suggestions are welcome.

  • mattmia2
    mattmia2 Member Posts: 9,475
    edited January 21
    Maybe the valves between the radiators were closed and now the second radiator is heating after years of not heating?

    The valves look to be in decent condition they will likely operate without a problem. The worst that would happen is they would leak out the stem a little and you'd have to tighten the packing nut. If they seal they will seal off the area where the stem is when they're closed.

    You can remove any of the dope and tape that is exposed, the part that does the sealing is between the nipple and the fitting.

    If the radiator valve is new you can close it to close the radiator off from the system to replace the vents. If the system never cycles it will be impossible to balance it.

    If you cover part or all of the radiator with a heavy blanket that is another way to reduce the output.
  • Neild5
    Neild5 Member Posts: 163
    Blue monster thread tape was introduced in 2010, and any tape or pipe dope you see is not sealing anything so can be removed safely with a wire brush.
  • jjx
    jjx Member Posts: 3
    Thanks for the helpful comments mattmia2 and Neild5. Despite all my attempts to remove the smell, none worked. Fortunately, a day of unseasonably mild weather arrived and the boiler was turned off for a couple of hours. I closed the radiator valve and my family and I decided that we'd rather be cold in the living room than have to live with the awful smell for the remainder of the winter.

    We are now thinking about what we will do in the summer/fall. At the very least we will replace the vents with slow or variable models, though there are votes in my family to remove the old radiators/radiator cabinet and replace will all new parts (as the boiler appears not to be the source of the smell with two other radiators receiving the same steam being odorless).