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Radiator Condensate pipe doesn't hot like the others

We have a two pipe steam system in a house built in 1940. A few weeks ago I noticed our boiler was using more water than usual (it hardly ever used much water at all – I have to add water a few times a week versus less than once a week before). Then I noticed that one of our radiators wasn’t getting as hot as it used to. So I finally got around to looking at it and found two things – 1. The condensate pipe leaving the steam trap for the radiator never got hot, not even warm, and on all our other radiators that pipe gets pretty hot and 2. The inlet valve was dripping when the heat comes up (which explained the wet floor area near the valve).

So I figured maybe the steam trap (Hoffman Specialty No. 17C) was failed shut and replaced it. No change. Here are some observations:
1. The Condensate pipe and the trap itself don’t get warm. In fact, the nipple leading from the radiator to the stream trap doesn’t even get hot, just a little warm. On all the other radiators, that piece is too hot to even touch.
2. When I replaced the steam trap (exact same Hoffman No. 17C), I noticed that the condensate pipe was full of water. I’m not sure if this is correct but I would have thought that pipe would be empty since I thought the water would drain to the boiler in the basement (this radiator is on the 2nd floor).
3. When I removed the steam trap, water did drip out of the radiator, so I’m hoping the slope of the radiator is still OK. I checked with a level and the slope id definitely down towards the steam trap end.
4. The vent at the top of the radiator appears to work great. When the steam comes up that vent hisses like crazy.
5. I didn’t try very hard to close the inlet valve. It doesn’t feel like it wants to budge and I didn’t want to force it.

Attached are for pictures – two of them are annotated with observations.

Can anyone give me a suggestion of where to go from here? At first I wanted to have more heat from this radiator but now I’d be happy to stop the leak. Is it possible the radiator is clogged inside at the end near the steam trap? Is it possible the condensate pipe is clogged? And how do you check or fix these things? Thank you.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 17,084
    Ah... um. Well, a two pipe system with traps shouldn't have a vent on a radiator. Shouldn't need it. The air and condensate should go out through the trap, and then the trap should close when steam hits it.

    What you are describing makes me think that there is some kind of blockage on the return line, and that the radiator is behaving as though it is a very poor one pipe radiator, with the condensate trying to get back out the inlet. Try pouring water down the return line. It should flow perfectly freely. You can also -- since to pour the water down the return line you have to have the trap apart! -- try running a wire up into the radiator. That should go freely, too.

    Make sure the boiler is off while you are playing!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Abracadabra
    Abracadabra Member Posts: 1,948
    return line may have shifted and is now pitched incorrectly, leaving water backed up in the pipe. Check the pitch on that return
  • Craig_Gruber
    Craig_Gruber Member Posts: 7
    Thank you. Water won't go down the condensate pipe so that's not good. I I'll check the radiator in the morning. And yes, the heat is turned off and cooled down before playing. Thank you!
  • are there crossover traps on the end, which may have failed?--NBC
  • Craig_Gruber
    Craig_Gruber Member Posts: 7
    Well the radiator seems fine but the condensate line definitely appears to be clogged or blocked in some way. I am able to get a 12 AWG wire down about 10 inches (the pipe make a 90 degree turn about six inches from where I have it open. Is there some way to try to clear such a blockage (like a snake) without ripping open walls? It's half inch pipe.
  • Craig_Gruber
    Craig_Gruber Member Posts: 7
    And no crossover traps on the end that I can tell. thx.
  • Fred
    Fred Member Posts: 8,518
    It is most likely blocked somewhere near the bottom. Is there anyway to get that return loose in the basement and clean it out or snake from the basement?
  • Craig_Gruber
    Craig_Gruber Member Posts: 7
    "It is most likely blocked somewhere near the bottom. Is there anyway to get that return loose in the basement and clean it out or snake from the basement? " Does that assume that this line makes a home run to the basement? There is another radiator on another wall in the room that is working fine. And another radiator directly below this one on the first floor that I THINK is working fin but I will check. I'm not sure if they share the same condensate line but that's a good thing to check. Snaking with these tight right angles seems like longshot. Not even sure what tool to use for a half inch pipe to be able to make those kind of turns. Thank you for the idea. it's another thing to check.
  • Fred
    Fred Member Posts: 8,518
    Yea, making right turns in 1/2" pipe is going to be tough. That's why I suggested going from the basement. It can be done but it will take some patience. get yourself a snake with a 1/4" cable and cut the spiral end off of it so that it is 1/4" at the end and you won't have the ballooned spiral on the end to try to push through the turns.
  • Abracadabra
    Abracadabra Member Posts: 1,948
    Attach a wet dry vac to return line and listen if you are getting air or if return is plugged.
  • When the boiler has been off enough to be only warm, and not hot, put a garden hose fitting on the return, and connect the hose to a faucet. Don't open it up all the way. This will flush out anything in the return.--NBC
  • Craig_Gruber
    Craig_Gruber Member Posts: 7
    That is a really cool way to flush the line! I'll see if I can do that without flooding the house! Thx