1933 Tudor with 2 pipe vapor system

jalagna

Hey everyone, I recently purchased an old Tudor with a 2 pipe vapor steam heating system. Everything is original besides the boiler which is about 10yrs old. The system seems to be working “well” besides 3 radiators which are recessed in the wall. The supply side is hot and as you move across the radiator it gets cold through the trap. I replaced one of the traps last night and nothing has changed. Any advice, supply valve bad and maybe stuck closed? Thanks in advance!

EBEBRATT-Ed

Hopefully you have a system that was never butchered.

Sometimes if multiple traps go bad they can pressurize the return line and cause a rad with a good trap not to work due to back pressure.

You could also have a supply valve with broken internals that's not really open.

With the steam off I would loosen the union nut on the trap a couple of turns (just to make sure it's not seized) then tighten it and start the boiler. When you have steam go back a loosen the nut a couple of turns, don't take it off and put a pan under it see if you get steam up to the trap.

Does the return line from the rad warm up at all/

jalagna

Return does not heat up at all, I replaced the trap with a brand new one and the new trap is still cold. The 3 bad rads are in completely different rooms, opposites ends of the house. Should I still try to loosen the union a few turn to check for steam up to the trap? I’m leaning towards a bad supply valve. 

mattmia2

Is there an orifice plate in the supply? There could be steam in the return anywhere between that radiator and the vent and it would stop air from being able to completely vent from that radiator. It could be a bad trap at a radiator or at a crossover from supply to return or even a water seal that suddenly doesn't have a high enough water level if say the pressure went up a little.

Steamhead

Have you checked the vent on the dry (overhead) return, near the boiler? In most Vapor systems that's the only vent in the system, and if it is sluggish some rads may not heat.

Post a pic of some radiators, also any devices in the piping near the boiler. Also see if any makers info is on those devices, as well as any original radiator valves and traps. This will help us ID your system.

Jamie Hall

Something -- most likely something about the inlet valve -- restricting the flow to those radiators.

jalagna

Sorry for the large post and remember it’s an old Tudor that needs a lot of TLC, previous owners did absolutely nothing to maintain….

Rad on right is the one in question…

Old trap prior to replacement 

New trap installed


Different rad but this is a better shot of the supply valve (Handle broken but works) same one throughout house.

Steamhead

That's a Hoffman Vapor system. The Differential Loop and the #7 radiator valves give it away.

The main air vent is in a tee in the return line above the Differential Loop. Find it and post a pic.

If you want to switch to gas firing, that Slant/Fin boiler will run nicely with a Carlin EZ-Gas or Midco EC gas burner.

mattmia2

Those inlet valves are metering valves for the vapor system. Something may have gone awry in the valve such that it is only partially open where it appears to be fully open(or there may be adjustments inside). The system was likely designed to work without steam traps and to use the metering valves to supply just the amount of steam that the radiators can condense.

Jamie Hall

@mattmia2 's pretty well got it up there, except that Hoffmann Equipped Systems did have radiator traps -- as yours does -- in addition to the metering valves. No, I don't know why.

Ideally that valve will be open just enough (there is a calibrated sleeve inside) that the radiator gets hot almost all the way across -- but we can't check that just yet. See below...

A few really critical points, though, to help your system really work well.

First, find the crossover traps. There should be one at the end of each main, and it should go from the main into the associated dry return. There may or may not be drips to a wet return at the same location (one from the dry return, one from the steam main) or they may just be a water seal -- or, rarely, the main is counterflow and the dry return parallel flow and not drips are needed. Think like condensate...

If the crossover traps have been removed and vents installed, put the traps back and get rid of the vents.

If the traps are still there, make sure they are working.
.
The Hoffmann Differential Loop has one purpose in life, and it does it very well. It limits the pressure differential between the steam mains (actually, the header) and the dry returns to no more than 7 ounces per square inch. In order for it to function properly, all the dry returns must come together in one point, at or very near the Loop, and all the venting for the system must be located at the Loop. No vents anywhere else! Check and make sure that these two points are still true, and if they aren't, figure out how to restore the system.

Now if the Differential Loop is still pipes and vented correctly, that valve we spoke of should limit the flow of steam correctly. If not, they can be disassembled and and adjusted, though it's a bit painstaking. There are YouTube videos on that, I think.

One more thing: in this system -- as in any vapour system -- the steam pressure must not be allowed to go above 7 ounces per square inch. The Hoffmann Equipped System -- if the Differential Loop is still piped and vented correctly -- will continue to work at a higher pressure, but not as well, and you would be wasting fuel.

Therefore... you need a vapourstat for control, if you don't have one, and it should be set for 6 ounces per square inch cutoff with a 3 ounce per square inch differential. You should also have a low pressure gauge to check its accuracy, although if the Differential Loop trips (you'll know by finding the dry return steam hot at the Loop) it's set a bit high for cutoff and needs to be adjusted down.

You should also have a pressuretrol, set for perhaps 2 to 3 psi cutout, as a safety.

I might note that if someone has modified things so the the Differential Loop is not piped and vented correctly, your heating may be uneven, you may damage traps, and you may have problems with condensate return. So fix it...

jalagna

Thanks so much for all the responses! I wonder if there is anyone in NY specifically on long island that can help in person…

Steamhead

There are plenty- go here:

https://heatinghelp.com/find-a-contractor/state/NY

mattmia2

I think I see a pressuretrol in your pictures so a vaporstat is probably the first step here.

jalagna

I have both 

Jamie Hall

jalagna said:

I have both 

Bravo! What's the vapourstat set for?

jalagna

Sorry I only have a pressurtrol… 

Jamie Hall

Um... get yourself a vapourstat. You really need it to control that system to get the best and most efficient performance from it.

ChicagoCooperator

I'm going to circle back to something - in your first post you say the supply side is getting hot. It it just the pipe getting hot or just part of the radiator getting hot? I've been led to believe that they don't actually need to be hot all the way across, as long as the room is comfortable, that should actually be the correct function. (experts chime in)

Jamie Hall

Not an expert, @ChicagoCooperator , but i've always heard -- and tried to shoot for -- around 80% of the radiator hot after an extended run. If you have that, you don't even really need a trap at all. Nice to have, though...

jalagna

1/2 of the radiator on supply side gets hot… 

jalagna

New issue to report lol… i started to notice my water level sight glass to be bubbling, I removed and saw the gaskets were rotted, so I changed them. Sight glass is still bubbling and when i open the drain on bottom of the boiler air comes out which takes almost all the bubbles out of the sight glass but in order to get water out of the drain i have to manually open the prv on top of my boiler which then releases the air which gets me water out of the drain. Also noticing  extra banging and water gurgling from some rads, Thoughts on this? 

Jamie Hall

The above is very odd. With the boiler off and cool, what is the level in the sight glass? Does the level in the sight glass move as you add or release water?

There is no way on that system that you should have to open the pressure release valve to drain it. Nor should there ever be bubbles in the sight glass. Something -- or somethings -- is very much not right, but honestly I'd have to get hands on to figure it out from what I've read so far.

jalagna

The water level is usually fine when off and cool. I check it every so often and make sure it’s at the right level. The other day I checked when the boiler was running and I noticed bubbles and a drip so I closed the sight glass valves, took the glass out a realized the gaskets were bad so I replaced gaskets and reinstalled. After reinstalling I added some water to get the level back to normal about an hour later the level was to high and bubbling so I went to drain some water out and air was coming from the drain hose, I had to open the relief and in doing so the bubbles went away and I was able to finally get water out of the drain and the level back to normal. 2 days later (today) I have the bubbles and high water again….

Jamie Hall

Something is just not right.

Air was coming from the drain hose? Where is the drain hose hooked up? It should be at one side or the other or the other of the boiler at the bottom, or on the wet return before the Hartford Loop connection. There should never be air at that elevation in the system.

Further, air should be able to freely enter the system through the vents, unless you have vents which will hold a vacuum (rare) and the system is tight enough to hold the vacuum (even rarer), so water should flow freely from the drain unless the drain is clogged with sludge (which is common enough).

When the boiler is firing, the water in the sight glass may move up and down some, but not all that much -- an inch or two perhaps -- and not violently. I can't see any mechanism to get bubbles in the sight glass, as water is not actually boiler in there.

If, after the system starts steaming, the water level in the glass starts to drop more or less steadily, that may indicate that you have slow wet returns. That happens. They may even be slow enough to stop the boiler on low water. If that is happening, then an autofeeder may add water to the system -- which isn't needed. Rather, what is needed is to set the delay on the autofeeder to allow the water to return -- and clean out the wet returns. That may account for the high water.

If the boiler water stands above the top of the sight glass, you will have problems with water in the radiators and banging. Almost guaranteed.

So... let's try a little experimenting here. With the boiler cold, adjust the water level to the normal level.
Get the boiler running. Close the manual shutoff valve to the automatic feeder. Now open the drain cock a bit The water level in the sight glass should drop slowly and smoothly as the water runs out. When the water level reaches the low water cutoff, the boiler should stop. Open the manual autofeeder valve; water should feed (possibly after a delay) and when the water level rises above the cutoff, the boiler should start again.

Stop the boiler and note the water level on the sight glass. It will probably rise slowly as condensate returns. Note how long it takes before the water level stops rising; that will be the delay you want for the autofeeder. Leave everything off for half an hour or so, then come back and -- using the drain -- lower the water level back to normal running where it was when you started.

Now a variation. If you don't have an autofeeder -- the above assumes that you do -- water is getting into your boiler from somewhere else ("2 days later (today) I have the bubbles and high water again…."). Before you do anything else, find out how it is getting in -- leaking by on a manual feed valve? Is there a domestic hot water coil which leaks?) and fix that. Then you can run the above experiment, but instead of having to drain excess water from the autofeeder operation, you may have to add water to replace what you manually drained to bring it back to normal. The boiler should restart as condensate returns; stop the boiler at that point and continue from "note the water level".

This likely will not get us to the root cause of your problems. However, if things do not go as outlined above, those things will need to be corrected. In particular, if the sight glass does not reflect the water level, that must be fixed; it may be that the ports into the boiler are partly blocked. If the low water cutoff does not stop the boiler, that absolutely must be fixed -- that is a critical safety.

jalagna

Not air, the drain is actually pulling a vacuum and only way to get water out is to open the vent. I do not have an auto feed. See picture, drain bottom left and vent top. Everything seemed ok with water level (just now) but i wanted to see if i got anything from the drain, so i opened it and it was pulling a vacuum. I have someone coming to check it out next week.  Anything i should be concerned about or in danger of? Thanks so much for your time! 

jalagna

Jamie Hall

No danger particularly -- but the fact that you can pull a vacuum on the system indicates that air can't get it naturally -- nor out. If you have vents, they are almost certainly jammed shut or broken shut. This will cause all kinds of problems with the system, and should be looked into. Can you locate any vents on the system and, perhaps, show photos of them?

Steamhead

Steamhead said:

The main air vent is in a tee in the return line above the Differential Loop. Find it and post a pic.

Found it yet?

jalagna

Thanks again for the quick response… I don’t see any vents….

JUGHNE

Can you post a picture showing the equalizer pipe connected to the end of the horizontal header and where it drops and connects to the boiler.
Something looks pretty small in that location.

Jamie Hall

Look everywhere -- ends of mains, along dry returns...

If they aren't there, we're going to have to figure out where to put them...

jalagna

Can’t find any vent… see pic 

Steamhead

Oh, it's there. It has to be. Follow the pipe coming out of the top of the Differential Loop. After it elbows horizontal but before it heads out to the dry returns, I can see a tee with the bull pointing up into the ceiling. Open the plaster around this and you'll see the vent.

The original vent was a Hoffman #15, long since discontinued. Pretty much anything modern except a Gorton #2 would be too small. Tell us what you find.

jalagna

Thanks! I’ll try!

Jamie Hall

I'm betting that when he finds it that you are right, @Steamhead -- it will be a 75 or maybe even a 76. And that it's stuck closed.

Steamhead

Jamie Hall said:

I'm betting that when he finds it that you are right, @Steamhead -- it will be a 75 or maybe even a 76. And that it's stuck closed.

I've seen even smaller vents on Differential Loops- Hoffman #6, 16 or 4A. And if I held my head at the right angle, I could hear the "huh-huh, huh-huh, huh-huh" echoing from when Beavis and Butt-head were there installing those vents........

jalagna

Not sure what type or how I’m going to change without taking down a bunch of plaster… ughh 

jalagna

One more 

Steamhead

Hoffman 75 or 76. How much clearance do you have above it, and at the sides?

jalagna

Some room in front and top but, on the opposite side of where the picture is taken it’s tight on a beam

neilc

well someone managed to tighten it onto there,
maybe try a basin wrench from below,
or open it up more