Steam leak

PhilKulkarni

I have a 8 year old Crown boiler for a one pipe steam. I have been losing approx a gallon of water every 4 days and the water level in the sight gauge drops a lot while the boiler is heating. It used to stay pretty level before this leak manifested itself. Also the pressure drops from 1.2psi to 0 abruptly 1-2 times each heating cycle and the radiators don't see steam for a long time, so I am just burning gas away. I have attached some pics.

All returns are above ground and the wet returns are in the basement and though fully insulated, there is no visible water anywhere. I have yet to overfill the boiler to see if there is a leak at the top. I don't see any steam escaping from the boiler, but I have not taken the cover off to confirm this is the case. Probably leave this to a pro. I have not inspected the long header in the unheated crawl space and the dry return because it has been cold in the NYC area. There are no water stains anywhere along the walls or ceilings. I have checked, and none of the radiator valves are leaking. I will perform a tissue wrapper test on each valve to be sure.

How best to find out if one or more risers in the walls leaks since this is possible? Can people who detect leaks using infrared cameras detect steam leaks reliably when these risers are insulated with asbestos which can cause the steam to spread all over the pipe because it is probably loose fitting? Have I left out any troubleshooting approaches?

Jamie Hall

Sorry to say this -- but the most likely place for a leak of that sort is in the boiler above the water line. You may be able to see a plume of steam escaping from the chimney. It is unlikely that there is a leak in a steam line.

EBEBRATT-Ed

@PhilKulkarni

a gallon of water is a lot of water to loose. Risers are very doubtful to start leaking. If they were you would see it in the basement.

8 years seems young for a boiler failure but we have seen them fail in that time frame, but that would be unusual if water was seldom needed to be added. I guess check the crawl space and take it from their. Could be an air vent back in their leaking at th e end of the main

mattmia2

Start by flooding the boiler up to the supply piping above the boiler and see if water leaks out.

PhilKulkarni

The boiler test passed, so I inspected the air vent in the crawl space and true to its name, the Big Mouth was merrily venting steam, perhaps faster than it vents air. I have attached a pic of the offending vent after two months of venting steam. The vent was installed 2 seasons ago and is identical to one I have in the other steam main heating the back of the house. That failed after one season but I spotted it since it was in the basement. The company sent me a replacement thermostatic cartridge and it has worked fine this season. Replacing the cartridge requires some ingenuity since the brass stop is brazed to the bimetallic disc and gets loose easily when you try to unscrew it from the body.

Many thanks to @EBEBRATT-Ed and all others for their helpful suggestions.

EBEBRATT-Ed

Glad it wasn't the boiler

PhilKulkarni

I should hedge a bit; I checked the boiler for leaks at the bottom only. I may have a leak, possibly at the top of the boiler along with the leaking Big Mouth, but not probably. Figured I’d wait and see if the water intake stops now before looking at the chimney for escaping steam. It has been fairly warm in lower Westchester lately.

Crown does apply a sliding ‘discount’ on a new replacement boiler of the same capacity for up to 12 yrs if it leaks. However, their fine print says boiler leaks due to corrosion are only warranted for 12 months. They said a leak after 8 yrs would be caused by corrosion and want to see pics with the top off- rather confusing.

PhilKulkarni

A day after replacing a vent stuck open, I still have some persistent problems regarding the leak. Now when the boiler starts up and the pressure reaches 1psi, there is sudden decompression and it goes to 0, then quickly reaches 1psi again and after a few moments begins to oscillate between 0.5-1.00psi. The oscillation stops in a few mins. The oversized boiler which used to shut off on pressure now goes on heating for a long time and only shuts off on pressure occasionally, and when it does, the pressure goes up from 1psi to 1.8psi abruptly and the trol cuts out.

Meanwhile the boiler level during the heating cycle drops in the glass about 2.5” but the water returns to the boiler much quicker than before and reaches the same level after the boiler cuts out. I also noticed chunks of metal when I drained the boiler about 1/2 a cup of water on a whim. The water is pretty clear, but I only refilled the boiler 2 days ago to check for leaks.

There are no leaky pipes so I am looking for some help on what to check next. Should I repeat the boiler leak test by overfilling the boiler to the ceiling this time? What might be causing the sudden pressure loss intermittently? The radiators seem to heat normally. Thanks in advance.

Jamie Hall

The number one symptom of a steam leak is having to add water -- which, I presume since you are still looking, you are still having to do?

But the amount you have to add is important information. Even what looks like just a small drip can add up remarkably -- one typical drop every 10 seconds, for instance, is 2 gallons in a day.

An abrupt drop in pressure such as you describe can only be one of two things: something, somewhere, opened -- or the burner shut off. The latter, I think, we can ignore! So the question is -- what. Small jitters in pressure are quite normal, particularly if the port on the boiler to which the pressure gauge is connected is near the water level, but an oscillation is... odd. Honestly, I'd really have to be watching it to get much further than that. Sorry.

EBEBRATT-Ed

Maybe you big mouth vents are acting up

vincentac1

I would also go around all your valves with a small mirror and see if it fogs up. if it does the valve is leaking and could be part of the water consumption problem.

PhilKulkarni

I a made a 2min video clip which I could have attached to show how the pressure in the boiler is behaving but this site does not support MP4 video. The pressure variation is greater than normal since the water usage went up two months ago. Before, the pressure never dropped to 0 from 1 in 20 sec while the boiler was running. Now in a 3 min interval the pressure goes from 1 to 0 PSI and back to 1 two times.

The Big Mouths on both front and rear mains are now fine, and a wrapped tissue test of radiator valves was negative. So far the water level is steady, thus the feeder has been quiet. Before the feeder would go off in 3 days.

The Big Mouth in the crawl space and is on a 1" tall stem because of the low ceiling ht. I might try putting a 45 angle.

I blow down the boiler once a week to protect the LWCO probe. But the amount drawn tends to be one cup or thereabouts depending on the start or end of the season. I drain it only till the crud comes out and stop.

If the pressure oscillations are due to a steam leak somewhere then I need to get a pro since I can't find it in the obvious places including the steam mains and both pigtails. If not, I would welcome more trouble shooting approaches. Thanks in advance.

EBEBRATT-Ed

@PhilKulkarni

Well if your feeder isn't feeding and the water level is good then you not losing water. Outside of making sure the pigtail to the pressure control and gauge are clear make sure the sight glass connections are clear as well.

The only thing I can think off to make the pressure fluctuate is the big mouths venting.

To test that if your convinced the pressure is dropping and not acting like it used to stick a couple of pipe plugs in the big mouths temporally and run the boiler see what happens.

Be careful removing the plugs if the boiler is steaming, no dope just screw them in hand tight

PhilKulkarni

Thanks for your help. I checked the main vents, radiator valves, all visible joints, and the boiler after flooding it for leaks and found none. The pigtails are clean and the boiler ports for the pigtails are clean too. Yet the pressure drops to 0 from 1.2psi then oscillates slowly between o and 1.5psi. Runs for a while then shuts down on temp. Used to shut off on pressure until this peculiar behavior. Stumped.

EBEBRATT-Ed

Well, good news that the boiler is not leaking.

The only thing I can think of is possible a pipe has sagged a little and is holding water. This could make some steam condense and drop the pressure prematurely.

PhilKulkarni

There are 2 large rads with about 2’ of horizontal runs that have a1.25” dia that connect them to the header. Not done any work on them but they are visible when I remove the lower grille on the rads. I checked the valves there for leaks before my last post. The pitch may be off a bit since I get an occasional hammer after a cold start on one of the two. The pressure gauge itself is ok. Sagging pipes due to broken hangers is a check I will do.

PhilKulkarni

Repeated the boiler leak test with boiler water pressure at 1PSI. That is well over the top of the boiler perhaps into the header. Let it stay for 6 days and found no leaks. Here is a link to a short video clip:

https://youtu.be/Q0AkLTA91L8

Checked main vents and radiator valves for leaks and found none. Appreciate any suggestions.