Steam riser issue

Gus_S

Hello all,
Trying to figure out an ongoing issue I've been having with my residential steam heat and I was hoping I could get some help from The Wall. Boiler is a Burnham 125k BTU, 2 years old, cut out is 1.5psi, cut in is .5psi. The house is a 1950s, single family, 2 story cape with 6 older style fin tube radiators on first floor. The second floor has 3 new stand up cast iron radiators. Main is vented with Hoffman Big mouth, rads have a variety of Gorton 4,5,6 valves. The system runs great except for one thing...once I replaced the upstairs radiators this fall, one of the rooms has had a really noisy riser. The riser is close to the boiler vertically, almost directly above it on 2nd floor, and starts to warm soon after boiler steams, but is the last one to fill completely. Towards the end of the cycle, as this is the last rad to fill, I hear a perculating noise coming from the horizontal run out. (Not a loud or banging water hammer.) It slowly makes it's way to the riser and lasts for a few seconds until rad is full of steam. I've checked the pitch on both the rad and the run out and they are good. I've also tried many different vent valves from Gorton 4 to C, and even a varivalve. All have proven to be of no avail. Another note, this noise is more pronounced when boiler comes out of night set back. (65 deg set for night, 69 deg set for day.) A nuisance to say the least as this now serves as an alarm clock since riser runs through my master bedroom. Thanks all, any advice would be greatly appreciated. 

ethicalpaul

The clues you provide suggest to me that there is a "valley" or "dip" somewhere in that line that is holding water.

That would explain:
- the radiator's reluctance to heat
- the gurgling sounds

You said "...starts to warm soon after boiler steams". Did you mean the riser, or the radiator?

What is the size of the pipe in this riser?

There is usually a short horizontal section in the joists just before the riser that you see at the radiator. This could have a low spot due to settling, or a different height situation after the radiator replacement.

You might try slowly (like 1/2" per day) raising the problem radiator to see if you can indeed raise it, and to see if that eliminates the valley.

Fred

I agree with @ethicalpaul, there is either a pitch problem with a horizontal pipe (maybe under the floor) or possibly a bow in the pipe allowing condensate to pool (less likely on a short horizontal run. The other possibility is that the riser or horizontal pipe is very small (like 1") and the vent you are using on that radiator vents so fast that steam and condensate can't occupy the space inside the pipe (at the same time). Use a slower vent and see if that resolves your problem.

Gus_S

Thanks for the replies @ethicalpaul and @Fred. To answer your questions, the pipe is 1 1/4". I've jacked the radiator up as much as I can safely do so considering I'm working with 70 year old pipes. Attached are pictures of the boiler (basement), radiator (2nd floor), and the horizontal run out to the riser with a level on it. Sorry for the close up, it's in a drop ceiling. Note horizontal run out is only about 3 feet long.

ethicalpaul

70 years is nothing to steel steam pipe and iron fittings. It's not going to break. Especially 1-1/4", which I'm glad you have for that radiator.

Where is the horizontal run that you are putting the level on? Is it just inches below the radiator? Because that's the one I'm thinking of.

Is it the same horizontal runout you mention here: "I hear a perculating noise coming from the horizontal run out"

How can you hear the horizontal runout? Do you hear it from where the radiator is?

ethicalpaul

Also congratulations, that boiler piping looks pretty good. The other details on the boiler are nice too. I see a pressure relief valve correctly piped to the floor, I see two pressuretrols, one with a manual reset, I see a skimming nipple installed.

I'm familiar with that radiator you have there, I think it is probably about 2" shorter at the valve than an old radiator (but I don't know exactly what you had there before). So I really would explore gently slowly lifting it with a 2x4 to lever it.

Fred

@Gus_S Try a slower vent on the radiator. Given that radiator riser is nearest to the boiler, it is possible that so much steam is flowing (creating a good amount of condensate) that both can't live together at the same time, in that pipe.

Gus_S

This is the horizontal run that's about 3 feet long coming right off the main header. Its pitched towards the main (to the right on picture). This is where the noise starts from. That goes to a 90 elbow that connects to a 10 foot riser which runs up through my bedroom. That then connects to another small horizontal run under the second floor subfloor, but that is only about a foot before it goes to supply valve, and that from what I could tell is pitched by me lifting the radiator.

Gus_S

@Fred -Update: I tried switching to the smallest vent I had on hand which happened to be a #4. It actually made it worse. The noise was the same but it lasted longer. I'm thinking my only option is to deal with it for now and cut out the horizontal run in the spring and replace it. That way it'll be pitched right for sure; and who knows how much build up is in that pipe. Inch and a quarter might be down to half inch with 70 years of build up. I bought the house recently, I'm pretty sure the previous owners never did any maintenance on the heating system. I had to replace the boiler because the one that the house came with had a crack above the waterline. (Running non stop, make up every cycle and white smoke billowing out of chimney, I'm surprised it didnt cause them any worse problems.) Good thing I had already put in new heat pumps to keep us warm while I did the install. Thanks for all the help folks, it's great having a resource such as this for help. Thanks for the comments on my boiler install @ethicalpaul

Gus_S

@Youngplumber it does not have a drip leg. The whole system is 1PS with a wet return and no drip legs. I definitely agree that I have a vaccuum as the vents on that side of the house, there are 3 of them all suck in a lot of air at boiler shut down. It's weird how this issue started when I installed the larger radiator, its definitely throwing me for a loop.

EBEBRATT-Ed

I agree with all the potential "fixes" that @ethicalpaul & @Fred mentioned. There is water hanging up somewhere.

@Gus_S said:

This is the horizontal run that's about 3 feet long coming right off the main header. Its pitched towards the main (to the right on picture). This is where the noise starts from. That goes to a 90 elbow that connects to a 10 foot riser which runs up through my bedroom. That then connects to another small horizontal run under the second floor subfloor, but that is only about a foot before it goes to supply valve,

So Gus in your minds eye get inside the pipe and pretend your a drop of water. We start at the radiator which is pitched back to the supply valve the water drops down around a 90 and through a short horizontal run out (which we don't know the pitch of) around another 90 through a horizontal runout around a 90 another horizontal pipe, another 90 drops down the riser around another 90 and back to the main.

Is that close to what you have

This is where I am a little confused.

Is this water draining back to the main header? It shouldn't be. Or is it going to a main steam line pitched away from the boiler. It should be.

The other clue is you say it got worse when you installed the larger rad. That makes sense. More condensate going down more steam coming up

Check the EDR of the radiator. I would be surprised if 1 1/4 isn't large enough.

I would have though a smaller vent as Fred suggested might have worked.

Basically it's pitch/water laying in a pipe/condensate and steam fighting somewhere.

Every steam line has to have a way for condensate to get out

ethicalpaul

Don’t worry about the vacuum—that happens at the end of firing, after your noise and lack of heating occur. The vacuum happens in every system after each firing

Fred

@Gus_S , did you push that supply valve down into the floor in order to get it connected to the radiator? There is water pooling somewhere.