banging radiator far from boiler; maybe a vent will help?

jwalker

Hi. I purchased an old Chicago two-flat a couple years ago, and with the help of Dan's books and this website, made some great improvements to the system. I'm at the point where it seems that improvements are going to come with some professional re-piping, but I would like to get the opinions of the folks here.

Here's my issue (and forgive me if I get the nomenclature wrong; it's been almost two years since I read "We've Got Steam Heat".) I have a room on the second floor that contains two radiators. They are fed from a header that comes off the main in the basement, where it becomes the return. I can't see the pipes, but I'm nearly certain that the two radiators are connected via a T junction that caps the vertical portion of the header. One radiator is 3 columns; the other is 8 columns. See the attached diagram, and sorry for the roughness. (The top is how things are currently; the bottom is my proposed idea, discussed at the end of this post.)


The issue is that 8-column radiator will bang and gurgle, and it used to spray water out of the vent. And I mean spray. This has been improved significantly by replacing vents on the main, the vents on all the radiators, and adjusting the venting so that the rest of them vent slowly while this guy vents quickly; the idea being to get them to all heat at the same time. However, this radiator still bangs on cold night and heats up last.

I hired one of the recommended contractors from this website and their technician was unable to come up with a fix for this, suggesting "make sure the radiator is tilted back". This was one the first things that I did to all of the radiators, and tilting this radiator further did not help.

My guess is that there are two issues. The first is that I have wet steam because of piping that I don't want to replace because of great cost. The other is that the header that feeds the two radiators in this room should have more venting capacity; it's a lot of air to vent through two radiator vent (a two-story climb, plus 10 ft horizontally to each radiator). If you look at my diagram, I think that ideally you would have a vent at point 1, where the T junction is. Then the radiators would only have to vent that last horizontal bit of the header. However, that T is in wall between the floors along central support beams of the house. Tearing in to get it would be more cash than I can afford currently.

So, my question to you all is what would think about adding a vent to the header going to the big radiator, just before the valve? I've drawn it in the bottom diagram as a bulb coming off a T just before the radiator valve (point 2) Would something like this work? I want to know what you all think and whether I should propose this when I have somebody come to do some other steam work for me. Of course, if you all have other suggestions, I'm open to them.

JUGHNE

I would guess that water is trapped in the horizontal piping to the offending rad.

You could try to raise the entire radiator on both ends 1/2", then raise the vent end another 1/2".

This may raise the pipe under the floor enough to have it drain back towards the vertical riser and keep water out of the rad.

neilc

you're trapping condensate at that rad, or in the supply lateral to it,
does that lateral have good pitch back to the riser?
no dips or sags at the valve or rad?
raise the rad up as high as you can, 2x4 blocks,
the fast venting is also holding the condensate from draining back,
rad must vent slow, the added main would be better at the top of the riser,
the fast venting in the lateral can hold the condensate from draining back,

bburd

More venting is likely to worsen the banging and gurgling. Condensate will be produced more quickly. Water is trapped somewhere. Have you taken the supply valve apart to make sure it's in good condition? Sometimes a washer gets loose and blocks the flow of condensate.

jwalker

Thanks for the quick responses!

I don't know about the shape of the lateral pipe, because it's between the floor and 1st floor ceiling.

Good idea to try raising the valve/radiator as much as possible to pitch the pipe. I can try that; hopefully nothing prevents it from coming up further.

bburd said:

Have you taken the supply valve apart to make sure it's in good condition? Sometimes a washer gets loose and blocks the flow of condensate.

I have not take the supply valve apart. This is one of the few valves I didn't have replaced because it seems to be in pretty good shape. When you say "take it apart", do you mean just detaching the radiator and checking that there is nothing blocking it internally, or more than that?

bburd

I mean remove the bonnet from the valve body and check the condition of the washer and seat inside. There should be no need to disconnect the valve from the radiator or the pipe.

Jamie Hall

All of the above -- plus a comment: if that top connection of the riser really is a T, one side or the other is going to be pitched the wrong way. You can't help it. In fact, if the riser is really vertical, both sides will be too llat. Wish they wouldn't do that. As has been said, raise the offending radiator as much as you can and see if that helps.

Changing the vent won't help.

jwalker

It looks like I've got about an inch to work with.

I'll raise it up and see what happens. If that doesn't work, I may try @bburd 's suggestion.

Thanks again for the feedback.

bburd

While that union is open, you can take a look inside the valve and see if the washer is in good condition and firmly fixed to the stem, and the seat is unobstructed. You might need a dental mirror. That way you don't need to remove the bonnet.

jwalker

After raising the radiator and turning down the venting, the gurgling remains. Maybe it's less, but not enough to really tell. Next time I have time and help to move the radiator out, I'll try checking the valve itself.

Other than those things, I guess my next options would be to 1) have the ceiling or floor opened up to redo the piping or 2) (more likely) just live with it. Right?

AdmiralYoda

@jwalker Did you quadruple check that the radiator is tilted towards the valve? Try and raise the vent end of the radiator another half inch.

Did you check to make sure the radiator didn't have any obstruction or big check of gunk at the inlet? Anything that could be preventing the condensate from draining?

When you disconnected the radiator from the valve...were you able to raise the valve/pipe any higher than in the photo? Every bit helps!

jwalker

That is as high as I can get the valve. There's another union below the floor that hits the floor, preventing it from coming up any further.

I can get the radiator vent end up another half inch and will do that.

Checking the valve and radiator near the union for gunk is a good idea. I will try that when I get some more help. My wife only has so much patience for helping muscle that radiator around. If I find some gunk, what would you think about vacuuming the mud leg with a shop vac? Will that do more harm than good?