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Typical temperature for steam wet return

I have a steam heat system with an uninsulated long wet return spanning the length of the basement. In the beginning of the horizontal portion of the wet return, we accidentally used a flexible concrete leveling compound under the drywall partition. The compound is definitely touching the wet return for a few feet. The maximum service temp for the compound is 170 deg F. Flashpoint is 185 deg F.

How hot does an uninsulated wet return typically get? I mean technically the condensate should be near boiling when it drains from the radiators, so I'm assuming above 200 deg F. By the time it hits the wet return it may be less and then it mixes with the contents of the return.

Removing the compound would be a major pain and I wanted to query the group before I start cutting into the drywall.

Thank you for your help

- H


  • Motorapido
    Motorapido Member Posts: 307
    I'm guessing the temperature could vary quite a bit on the wet return depending on how close it is to the last radiator and the transition from dry return to wet return. You can get a very inexpensive infrared thermometers at Harbor Freight (often called "Horror Fright" due to sketchy quality). They certainly aren't science-lab precise, but probably close enough for rock and roll.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    What's the leveling compound made of? And is the max service temp and flashpoint only apply until it cures, or always?
  • Fred
    Fred Member Posts: 8,542
    I would guess it to be 100 degrees or less. Keep in mind that condensate from each heating cycle will stack in the vertical return (the drop from the Main to the horizontal wet return at the floor) and remain stacked up to the normal water level of the boiler. Virtually all the water in the horizontal wet return will be cooler as, depending on the length of the wet return, which, in your case is the length of the basement, may be condensate from two or three prior heating cycles.
  • Jamie Hall
    Jamie Hall Member Posts: 22,956
    A dry return can indeed get hot, close to the radiator -- but should never be too hot to hold a hand on at least briefly more than a few feet away. A wet return, on the other hand, would rarely if ever be much over 100 and usually less.

    I'd be really surprised if that flexible compound kept that low a flashpoint after it had cured. If it does, I wouldn't want it anywhere around one of my projects! Keep in mind that #2 heating oil has a flashpoint range from 126 to about 200, depending on the exact mix. Check your MSDS on the stuff for more information.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • HenrikW
    HenrikW Member Posts: 8
    Really grateful for everybody's comments. I was able to get the product safety specialist from Sika on the phone and he confirmed that the product would essentially just soften up, but would not emit any harmful fumes; would not disintegrate. So - no longer concerned about safety.

    Many thanks!