New to steam - major leak in air vent

Knave72

I grew up in the west with exclusively forced air heating. A year ago I moved to Columbus, Ohio from Denver... I used to think of Denver as the east!
The homes in my neighborhood were build mostly between 1900 and 1940 - mine 1936 which puts it in the two pipe era apparently.
I of course found my way to a copy of "The Lost Art of Steam Heating - Revisited" and have been learning about the system. I'm an engineer by trade and figuring out how things work is always a lot of fun.

First observation - almost every radiator in the house had an air vent on it. Almost certainly because the steam traps have all long since failed. Its pretty apparent that this system has had virtually no maintenance beyond the boiler itself.

I have two different types of steam traps and zeroing in on the exact replacement part was a little tricky but now I know I need the TCHF-1409 for the Hoffmans and the TCTR2402 for the Tranes... I have 5 more on order and with that I will have replaced all the steam traps.

Hopefully this helps tame the pipe knocking! Every night it sounds like a steam ship setting sail (is that a mixed metaphor?).

I also replaced two air valves on the steam returns. There seems to be two loops through the house and the end of each loop had a hoffman model 76 which apparently was intended for the vacuum systems. I replaced them both with model 75's. One of them now works as intended. It used to just spray steam the whole time the boiler was on but now it seals...

The other is just pouring water out onto a puddle on the floor, see the attached image.
I'm hoping the replacement of all the traps will help but is there anything else I should be considering?

I should add also that I have contacted 3 different local HVAC companies and a couple people came out to the house and all of them declined to get involved...so I'm also learning that finding someone who knows how to service these systems is a challenge.

Thanks for any inputs.

Jamie Hall

The picture you show is of the lower end of a drip at the wet return. Can you take a picture of the entire drip and the associated steam main and vent?

Also -- in two pipe systems it is essential that the dry returns (the returns up at about the same level as the steam mains) be adequately vented. They do all the heavy lifting on getting air out of the radiators. Usually the dry returns will tie together somewhere right near the boiler, and have one or two or three big vents there, and then drop down to the wet return and thence to the boiler.

neilc

and I'm thinking boiler pressure , , ,
let's also see your Ptrol, and gage, and sight glass,
and then a distant shot or 2 showing the entire boiler, floor to ceiling, including the piping above the boiler

Knave72

Added additional photos - let me know if that gets what you need.

The pressure is hard to read there - its very dark in that corner so I had to jack up the brightness and lower contract. The pressure setting is 0.5 PSI - as low as it can go.

Knave72

Just noticed also a large swing in the water level from that last photo to the previous one of the sight glass...

neilc

inside the Ptrol there is a white wheel that sets differential, it shoulid be set to 1,

when the boiler is firing, what pressure do you see on the gage on the top of the boiler?
does the gage return to zero when the boiler is off?

could be the return under the leaker vent is clogged and not draining thru,
I don't see a simple way to check that (hose bibs),
I do see a union, but if you open that and let it flow, you're making a mess, caution, hot and dirty,
a good large wet vac, ??
If you take this on, shut the boiler off and let it cool, all that hot water will be coming your way,
or predrain the boiler and flush under a controlled fill,
but this may not "check" the return, vent to union, as well

Knave72

The gauge was reading about 2.5 with the system off and peaked just over 5 while the boiler was running.

The differential was at almost 2.

I figure if I'm still seeing problems after replacing the steam traps at all the radiators I will consider looking for a clogged pipe in the return under that air vent... not sure I even have wrenches big enough at the moment to even try that.

SteamingatMohawk

@Jamie Hall You stated, "Usually the dry returns will tie together somewhere right near the boiler, and have one or two or three big vents there, and then drop down to the wet return and thence to the boiler."

It is my understanding the dry returns/drips should not be connected to each other above the water level in the wet return. I had that problem with my single pipe system and we discussed it winter(s) ago on HH. It manifested itself in that the shorter rear main was venting through the longer front main vent in addition to the rear mains own vent, reducing the front main venting until the rear was totally vented. I solved that problem by repiping the rear dry return/drip to below the water line. More than one of the guys on HH agreed,

I tend to believe the same holds true for 2 pipe systems, but yield to you and other more experienced people on HH.

Jamie Hall

The thing to remember about two pipe dry returns is that they really are dry, in that -- if the traps or water seals are working correctly -- they never, ever see steam (well, hardly ever -- but let's not go there just now!). They should always be at, or very very near atmospheric pressure, and in fact in many early systems they just opened direct to the atmosphere! They are completely separated from the steam side of the system, either by traps or by water seals of both.

Thus there is no harm to connecting them together up high. Might as well.

In contrast the pipes often referred to as dry returns in one pipe systems serve to return condensate to the boiler in parallel flow systems, and are directly connected to the steam mains they serve -- and thus steam can and does get into them. If they are vented at the ends, steam will get all the way to the end -- and if they are connected together at the ends above the water line, steam will quite happily pass from one to the other, whichever is faster.

So there is a great deal of harm in connecting them together above the water line.

SteamingatMohawk

As I learned, but had to discover it on my own after years of having difficulty balancing my 1 pipe system.

Thanks,

Knave72

@Jamie Hall Your comments give me hope that once I install all the new traps (still waiting on delivery) that it will hopefully tame the air vent leaks.

That said - its so cold that the house can't get to 70 degrees and water is pouring out of the system so fast its triggering the low water cutoff. =/

delcrossv

Knave72 said:

That said - its so cold that the house can't get to 70 degrees and water is pouring out of the system so fast its triggering the low water cutoff. =/

I'm starting to think clogged, or partially clogged wet return.

Knave72

Latest updates - all the steam traps arrived so if I can find time away from work this weekend I will install and see how much that helps.

But the leak has gotten both worse and better. It is now pouring out gallons of water per day through the air vent. I have to empty a bucket several times a day.
I then went around the house and opened up every radiator including the guest room and the bedroom (both very large radiators that usually make it too hot!). For a couple of days the leak stopped or was just drips.

This morning its back to buckets... I'm baffled.

Knave72

So if I was to try to clean out the return, I'm assuming it is the return under the leaky vent ... even though steam systems are notorious for having problems in one place be caused by things in an entirely different location...

So to clean this out I would...

1. Turn off the system and remove power
2. Drain all the water out at the drain valve
3. Remove the two pipe unions shown in the diagram.
4. Clean out pipes as needed
5. Reassemble
6. Refill with water
7. Power up and cross fingers...

Anything else I need to be thinking about?

ethicalpaul

You don't need to drain at your boiler drain valve because that will drain the entire boiler but will leave the water in the wet return anyway (the hartford loop, the short vertical section above your drain in the drawing above separates the wet return from the boiler water.)

Just undo that left union and do whatever you have to do to catch or soak up the water.

Then install Tees and valves where I made the purple circles below. Valves that have hose bibs on them are handy because then you can hook the hose to a spigot on one end, and run a hose to a bucket or drain on the other end. Then you'll be able to flush the system at will.

Be prepared that when you disassemble these pipes some might crumble, especially at the threads. I wouldn't open those pipes unless you have a replacement plan. You can use copper pipe under the water line if you're more comfortable working with that. You can even use Pex but nobody does. It would be fine for a temporary fix also.

You don't need to fill the return with water, it will fill itself with condensate. Just keep an eye on the boiler water level because that will drop a bit as the return fills.

JUGHNE

IIWM, I would get the return cleaned and pressure under control before replacing traps.
If you crack the lower union and catch any water that you can, that may be less mess.

Have you opened any traps and checked inside?
I found one system with no guts in the traps.

The theory is that you want to change all the traps before firing the system back up or you risk damaging the new elements you have installed.

I would check that all the caps can be removed first, if you haven't already done that.
Correct socket on impact works well.
Then just tighten them so they don't leak.

I would then clean the return and pigtail and fire the system back up and see what happens.

Maybe change all the traps the next day.

If you change many conditions at one time you are unsure of what was the actual problem. IMO

No floor drain??

SteamingatMohawk

With the boiler off and somewhat cooled down, as a possible shortcut before you disassemble the union(s), can you remove the vent and us a small diameter snake of piece of wire to see if you find anything.

Even a piece of copper wire can be used, just make sure whatever you use that you make sure it can't fall into the pipe. What diameter is the pipe you are concerned about?

At this point, I would not use a power auger, so you don't damage the pipe with a tool that is too aggressive.

Post the results if you do it.

delcrossv

I'm with @ethicalpaul on this. While you're at it, get rid of the offset at the bottom of the drop to the bad wet return. Straight down to a tee with a drain/ flush bib. same on the other side.

Seems you have a reverse slope to the drop. That collects crud like a trap. Better would be to remove that slope and have the wet leg truly horizontal.

Knave72

Latest update... I tried loosening the unions once or twice but it wasn't budging. I haven't tried all options but I did decide to spend the time available replacing traps. All traps have now been replaced in the house.

I don't know if its related, but the vent that "works perfectly" above at the end of the steam run is now working like a tea kettle. I replaced that about 2 months ago and this is the first I have noticed it not working again.

So I'm almost back to square one and my heat bill was $400 this month.

I would gladly call a professional to help but I can't find any...

I'll tackle the wet returns next and let you know what I find... I can probably at least find a regular old plummer to help me with that part.

delcrossv

You probably need larger wrenches and/or cheater bars to loosen those unions.

Knave72

OK - I think I have the answer. The wet return was perfectly clear...no clog at all.

So the water is not getting stuck coming down so it must be coming up...too much pressure in the boiler.
I think the pressuretrol is simply broken and the boiler never shuts off anymore from pressure feedback. It just keeps boiling away until the water is pushed out enough to trigger the low water cutoff ... or the temp is high enough at the thermostat. The pigtail was clear.

I ordered a new vaporstat to replace it and will know for sure once it is installed.

Also finally found a local guy who can help me and he already has large wrenches and cheater bars (both of which were needed!).

ethicalpaul

Definitely figure out what your pressure really is...that is one of the ways that water can get into your mains.

If it turns out your pressure is OK, then we have to figure that water is being "carried over" into the mains with the steam.

The overall design of your near boiler piping while not textbook, is reasonable, but even the best piping can't prevent carryover in all cases.

In your case, you seem to have a good size boiler, of Dunkirk design (with the side steam supplies). These are very prone to carryover in cases of oil in the boiler water or too small pipes causing too high of steam velocity.

I'd rather see your boiler be piped with a supply on both sides instead of just one. I'd have to look at your boiler's installation manual to see what size supplies they recommend.

Anyway, something to look at if you still have the problem after verifying your pressure.

JUGHNE

From what I can make out on the piping for boiler steam/main connection/header:
(unless there is a double header I am not seeing)

There is a F&T trap that looks like it is there to drip the header....upper right side.

I have had one in that location completely plug up and not drain water out of the header.......However in your case your equalizer drip/drop pipe is right next to it.

I could well imagine the F&T plugged up, but not an equalizer of that pipe size plugged.

If both were plugged then a large amount of water would be sitting in the header waiting for a ride out on the steam flow.

Just a WAG.

If the equalizer and F&T drip are next to each other, you may not need the F&T.
Maybe....

Knave72

With the new vaporstat installed the system is a completely different animal.

The pipe knocking seems to be almost completely gone (and what I do hear is probably expansion and rubbing) and there is no water leaking and the air vents seem to be working properly.

I've spent a lot of time watching the system over the last month and its just so obvious now... before, the boiler would kick in and just keep on boiling until the whole system was in chaos.

Now, the boiler kicks in for just a bit and shuts down before anything ugly happens. It almost seemed like it wasn't going to work because the cycles seemed too short and my radiators were no longer glowing red (slight exaggeration). But the temperature slowly and steadily climbed from 67 to 70 and leveled off with no problems at all.

During my research I can't even count the number of times I read that the pressure is usually the problem...but I trusted the controller and that threw me off.

Not sure why really good quality gauges are not a part of every steam system...I'll be adding one.

Thanks to everyone who posted and made suggestions. I learned a lot along the way even chasing the red herrings.