Spitting radiator

Alan (California Radiant) Forbes

One of my customers has had 4 contractors trying to figure out why this radiator has a spitting vent, ruining her floors, collapsing the garage ceiling below and driving her nuts. One contractor has replaced the vent, another one has sloped the radiator towards the valve, another one has corrected the belly in the piping below. All to no avail; the vent continues to spit.

Any ideas? Could it be something in the radiator valve that is preventing the condensate from returning to the boiler?

Jamie Hall

Double check the cutout pressure -- but you know that. There certainly could be a problem in the valve, like the disc having loosened... or even come off and acting like a very poor quality check valve!

JUGHNE

Disc/washer fallen of end of valve stem and lying on inlet opening? Steam would sneak past but water would see it as a drain plug.

Or HW only design of valve.......not "fat" enough to allow water to flow under steam.

Fred

That valve looks high, relative to the spud tapping/plug on the vent side. How is the valve connected to the radiator? Pressure may be too high. Has the pigtail been checked to make sure it is not clogged?

JUGHNE

Fred, that does look out of line, maybe it is the angle of the camera at the time. But it almost looks like it could have a 90/street90 offset......but no way possible! Huh?

Fred

JUGHNE said:

Fred, that does look out of line, maybe it is the angle of the camera at the time. But it almost looks like it could have a 90/street90 offset......but no way possible! Huh?

Yeah, that's the way it looks to me too but like you say, doesn't seem possible???

JUGHNE

If so it would leave 4-6" water in the bottom of the rad.
No way that would not be figured out.
Maybe Alan only has the photo to go by, not been there yet.

Alan (California Radiant) Forbes

Yes, you're right. It does look high, but it went directly into the radiator.
I'll replace the valve and see if the old valve looks suspect.

Thanks, guys!

EBEBRATT-Ed

@Alan (California Radiant) Forbes you mentioned they fixed the belly in the piping and also mentioned collapsing garage ceiling.

Just wondering if the piping is all exposed so you can check the pitch? Also, is the take off from the main on a 45 up? a 90 or a side takeoff is ng with 1 pipe

kcopp

How's is the water quality? Any chance oil got in there? Any work done on the system before this started happening? A good flushing would prob help a bunch...

Alan (California Radiant) Forbes

EBEBRATT-Ed said:

@Alan (California Radiant) Forbes you mentioned they fixed the belly in the piping and also mentioned collapsing garage ceiling.

Just wondering if the piping is all exposed so you can check the pitch? Also, is the take off from the main on a 45 up? a 90 or a side takeoff is ng with 1 pipe

This is the last radiator off the main; I believe a 90 rolled over and then a 45 to the vertical. Yes; NG, 1 pipe.

kcopp said:

How's is the water quality? Any chance oil got in there? Any work done on the system before this started happening? A good flushing would prob help a bunch...

As far as what the owner has told me, the system hasn't been touched for years.

Alan (California Radiant) Forbes

We went back today and replaced the radiator valve (even though the old one looked fine), replaced the pigtail on the pressuretrol (even though the old one was clear) and dropped the pressuretol setting from 2 to ½ psi.
As you can see, the take-off on the main is a 90° straight up. It's the last rad on the run. Slope is marginal.
We also stuck another shim under the far side of the radiator.
So, needless to say: the radiator still spits.

Steamhead

Is that a counterflow main?

nicholas bonham-carter

Is there an accurate low pressure gauge on that boiler?
As you may know we all have low expectations for the standard pressuretrol, which has been supplied with most boilers. Your pressure could be racing up in spite of the settings.
I think you could connect a clear plastic tube with hose pipe fittings to the boiler drain, hung vertically, and see by the rise of water line in the tube the pressure in the boiler.
How adequate is the main venting? If the rad vents are doing too much of the total, then there will be more water blown up into the mains.--NBC

Fred

Does the radiator heat properly otherwise? Almost has to be pressure related but I also wonder if that elbow is full of crud, still allowing some steam to blow through but making the condensate very slow to return? Just guessing at this point...

EBEBRATT-Ed

Doesn't look like enough pitch to me

JUGHNE

Is the entire system counterflow?
Book says 1" in 10'. It looks like that is a long main after it turns the in the corner of the garage.
Is that a eccentric reducer coupling hiding under the AB insulation....about 30" from the riser?

A crazy idea is to make this radiator a 2 pipe system.
Put an orifice in your new valve, perhaps pipe a dry return back to a wet return add a main vent on the dry. You wouldn't have to deal with the insulation doing this.

There are 2 pipe counter flow systems as I have described.
The steam main and return have the pitch back to the boiler.

Alan (California Radiant) Forbes

Frank: Yes, counter-flow.
Nicholas: The gauge is shown on image 4711 and from watching it, seems to be working. And I haven't found any main vents, so the radiator vents are doing all the venting.
Fred: Yes, the radiator heats properly and there definitely could be some schmutz in that elbow. That elbow is also pointing straight up, a conflict point of steam vs. condensate.
Ed: Agreed, pitch looks marginal.
Suggestions?

SteamCoffee

Partial Minitube....run new copper supply lines, use the old counter flow as a return.

Fred

I think we figure out why it's spitting water. Any conversion to anything else won't fix the real issue. JMHO. @Alan (California Radiant) Forbes , when I look at picture # 4710, it looks like the pipe pitches one direction, from the turn and another direction before the turn. What's the story with that or is it just the way the picture was taken? Are we completely sure the rad vent is good and that it isn't water logged and simply not getting hot enough to close? Have you shaken the water out of it? Maybe the drip tongue is shoved in against the radiator wall and bent upward (although that radiator has some very deep sections, the tongue could have been bent the wrong way when it was installed)?

JUGHNE

Fred, that corner picture 4710 does look like 2 different slopes but I would assume that everyone has checked that issue.
As Alan said the pitch is marginal though.

It is just a long main, not much pitch (gravity) to allow water back flowing against the steam. It seems if the condensate had it's own return it might solve the problem.

Any pictures of the NBP available?

Alan (California Radiant) Forbes

Jughne: Yes, the entire system is counter-flow. Good eye on that eccentric reducer; I think you're right, but do you think it would hold back any condensate. No pictures of the NBP. I'll get some when I go back. Where would you connect the dry return at the radiator?
The house is over 100 years old and it's worked all this time. We've had historical amounts of rain this year and the house could have settled, reducing the slope.
Fred: I think it's the way the picture is taken. There's slope, just not much of it. Good call on the radiator vent. I did not check it, but one of the previous contractors switched it out. Will check it when I return.

JUGHNE

The eccentric is meant to keep the bottoms of the two different size on the same plane. Avoid the pothole in the road.....for a parallel flow pipe system. Probably not needed for the counter flow as the water is flowing from smaller to larger pipe.

All the steam mains should have drips into the wet return at the boiler after the header, keeps the steam drier.

For the amount of damage done by one spitting vent it must have been leaking for quite a while. The entire garage section could have settled. You still have pitch back, just less of it.

Maybe the most challenging part would be getting a 1/2" opening into the lower right end of CI rad. A good place for an eccentric bushing if available. I suppose there has been a plug in it for the 100 years of existence. Then a trap with 1/2" drop and 3/4" back to the wet return. Good size air vent on the dry return pipe near the boiler keeps any spitting in that room.
This could be copper IMO. Leave the main as it.

This is my own idea concocted up in my mind.......I hope others will comment.....even say way it might not work.

JUGHNE

Any new developments?

Alan (California Radiant) Forbes

The project is on hold.

Robert O'Connor_12

Had a similar issue several years back. Checked all the obvious pitch, pigtail, pressure, water quality, radiator valve, pitch on radiator etc. .
I wound up removing the straight bushing in the radiator and replacing it with a eccentrically tapped one. It worked.

Robert O'Connor/NJ

Bob Gagnon plumbing and heating

I find the cause of a spitting radiator is usually a closed radiator valve, or poorly installed near boiler piping, delivering wet steam.

Thanks, Bob Gagnon

Alan (California Radiant) Forbes

Robert O'Connor said:

Had a similar issue several years back. Checked all the obvious pitch, pigtail, pressure, water quality, radiator valve, pitch on radiator etc. .

I wound up removing the straight bushing in the radiator and replacing it with a eccentrically tapped one. It worked.



Robert O'Connor/NJ

So, the standing water at the bushing was being carried up through the radiator by the incoming steam? That's pretty trippy.

Bob: In this case, the valve was fully open with no obstructions and I went ahead and replaced it anyway. Will check the near-boiler piping when I go back, but the darn thing has been working fine for 100 years.
I think there's an obstruction in the line or it's lost its slope.

Bob Gagnon plumbing and heating

The system is 100 years old, but how old is the boiler and near boiler piping?

Thanks, Bob Gagnon

Alan (California Radiant) Forbes

Boiler is a Peerless; probably 20-30 years old.

I'm going back there sometime this month and will give it the stink eye.

Harry_6

I've seen this happen with a vent near the end of the run when incorrect near-boiler piping allows carryover.

Alan (California Radiant) Forbes

Photos

Bob Gagnon plumbing and heating

It looks to me like that improper near boiler piping would allow wet steam up into the system, is it very noisy?

Thanks, Bob Gagnon

Fred

Well, The near boiler piping will always be suspect for any number of problems but I would say if the system pressure is low enough and there is great main venting on the system, radiator vents shouldn't spit. Are those vents on those drips the only main venting on the system? If so, I'd start by adding adequate main venting and see if that resolves the spitting.

Bob Gagnon plumbing and heating

Ar those black fittings on the water pipe? Maybe the same guy who installed the near boiler piping. If the boiler is 20 or 30 years old it's time to change the boiler and install correct near boiler piping with the correct b dimension. I bet that'll solve the problem...

Thanks, Bob Gagnon

Alan (California Radiant) Forbes

Bob: The system is not noisy.

Fred: Those are the only vents and it makes sense to change them out with something that vents better.