Boiler inexplicably losing water-pressure issue?

a2shutt

I'm having trouble with my Burnham IN-7 steam boiler (one pipe system) losing way more water than it should.

When the weather starts getting cold, the boiler shuts down from the lwco probably every 3 days and has to be refilled. It is fine all summer, which tells me that it is only leaking when it is running (obvious, perhaps).

I've been trying all sorts of things to determine where the water is going. There are no obvious leaks or water on the floor. I flooded the boiler before the season began and let it sit for 30 minutes or so with no obvious leaks. There is a small door at the base of the chimney (I can see inside), and there is no condensation or obvious moisture going up the chimney. Same view from outside-no significant vapor.

The backflow preventer drips occasionally, but not that much. All wet returns are accessible and not leaking.

This is a 7 unit apartment building, so tenants don't necessarily notice issues at their radiators. That said, no one is complaining about massive amounts of steam or water in their unit.

The system runs ok, but it seems a bit out of balance-some units stay way colder than others and some radiators take a long time to heat up.

The pressuretrol is set at 2 lbs main and the high limit is 6 lbs. My 0-30 lb gauge (not the best, I know) has usually read 0, but just recently (like today) started reading 4 lbs. Not sure if it is accurate or not.

I guess I'm wondering where to go next in tracking down this leak. If that gauge is accurate, I know the pressure is way too high. Should I adjust it down right away? How low can I go? Would higher pressure like that contribute to water loss?

I've had CSD-1 inspections done by two different local contractors that supposedly know steam, but I was left with the impression from both that I probably knew more than they did (about theory, at least) due to this site. So not sure who I would even call (there's no one locally listed on this site).

Thanks!!

nicholas bonham-carter

When you flooded the boiler, did you fill it well above the boiler top?
Definitely reduce the pressure, down to 1.5 psi max, verified by a good low-pressure 0-3 psi gauge, mounted next to the pressuretrol.--NBC

a2shutt

Yes, I filled it to the top of the sight glass then let it run for another 30-45 seconds. Really not sure where to go next in finding this leak.

Ok, should I also reduce the high limit? Or does that not matter for this purpose?

STEAM DOCTOR

Check all the radiator shutoff valves and air vents. Also check any main air vents.

STEAM DOCTOR

Dont expect the tenants to notice any leaks. These leaks are not always obvious. Also, ask tenants if there are any heavy hissings sounds. Often an indication of a leak.

a2shutt

The main vents are newer Gortons, and seem to be fine. Is it possible to lose that much water through the radiator unions and valve stems?

So I guess the next step is to go through each unit and check each radiator.

STEAM DOCTOR

Absolutely. Part of what keeps me in business. Going this afternoon to just the situation. Customer was refilling boiler almost daily. Had seven radiator shutoff valves and air vents leaking. Homeowner never saw a thing

a2shutt

Ok great. I'll do that. Does anyone ever use an infrared camera or something similar to find leaks of that nature?

Fred

The Pressuretrol should be set at about .5PSI Cut-in and 1PSI Differential. That will give you a Cut-out of 1.5PSI on an Additive Pressuretrol. If you have a Subtractive Pressuretrol, the Main should be set at 1.5PSI and the Differential set at 1PSI. That will give you at Cut-In of .5PSI. The pressures you are running can push steam out of radiator valves and couplings that would not otherwise happen at the lower pressures. Drop the pressure and see what happens.

KC_Jones

Most vents aren't rated for pressure as high as 6 PSI either so even if the vents are okay they could be leaking, or being destroyed by that amount of pressure.

HarryL

@steam doctor - Do you use a mirror to look for fogging while making steam, or something more high-tech, for finding the leaks?

a2shutt

Thanks for the input. I've got a 0-3 psi gauge coming. I checked the existing gauge this morning and it showed 2 psi, but again, not sure how accurate it is.

Fred, thanks for your explanation. I have a subtractive pressuretrol so I did what you suggested and we'll see what happens.

STEAM DOCTOR

null
I listen for heavy hissing. Usally I can eyeball the leaks. If in doubt, I put a tissue or paper towel on suspect area. Low tech but effective

a2shutt

Ok, I installed my new gauge and attached a picture of the setup.

I fired the boiler for about 15 minutes and the gauge didn't register anything. It bounced around for a few minutes about 5 minutes after I started it, then it dropped to zero and stayed there.

I checked the pigtail (blew through it) and it seemed clear.

Is this normal? It seems like it should show SOMETHING on a 0-3 psi gauge after 15 minutes of firing.

BobC

If the boiler is well matched to the building load you may not see any pressure until we seem real cold weather or you try coming back from a large setback (10 degrees or so).

Is the heat ok? Are you still losing water?

Bob

a2shutt

I'm still losing water but I'm guessing its from some radiator leaks. I'm working my way through the building Monday-just sent a notice to the tenants.

The heat seems ok, but not great. It seems like it takes a long time to heat up, but again, these are apartments and I'm not there monitoring every single area all the time.

I was just reading something from Dan Holohan about radiator 'panting.' Should my air vents blow a steady stream of air out? Because they seem to blow the air out in spurts. Not sure if that is considered panting or not. Wondering if that is connected to the lack of pressure reading on the gauge.

Thanks!

gcp13

If your boiler is leaking chances are you you will not build any pressure
Doesn't seem like you fill the boiler enough. usually you feel the takeoffs going to the header and add water to fill the boiler until those get really cold so you can tell the water is above the boiler and then let it sit
You could have pin holes or cracks on the top of the Boiler block much higher than the sight glass would be
You could also take the top Jacket apart and the draft hood to inspect the block
Just make sure you use furnace cement to seal the draft hood back to the top of the boiler when you reassemble

gcp13

I didn't hear any mention of piping, is it one or two pipe steam you may have underground returns that could be leaking

BobC

It sounds like panting and that is usually caused by steam going over small pockets of water in the mains or radiator lead out pipes, not enough to cause water hammer but enough to collapse the steam.

Old buildings settle and that can cause problems with the piping. Look at all the piping you can see because you may have some dips in the piping. Those dips will pool water and collapse steam, it's very important that all the steam pipes have correct slope. Mains need 1" of slope for 20 ft of run in a parallel flow system, if it's a counterflow main it needs one inch for 10 feet. A horizontal pipe that feeds radiators on the first floor needs one inch per 10 feet of run. A horizontal pipe that feeds radiators on the second floor needs one inch PER FOOT OF RUN. If you don't have the slope the pipe has to be one size larger to work well.

The Lost Art Of Steam Heat has all the info you need.

Bob

a2shutt

Right, I let the water run for about 30-45 seconds after it reached the top of the sight glass. It would have easily filled up into the header. Everything seemed dry.

Its a one pipe system, but the wet return is all exposed and seems good.

Thanks, I'll try to look for some dips in the piping.

Fred

When you check the radiators, feel the floor under the supply valves and, if possible the underside of the radiator as well as where the radiator vent screws into the radiator. So much water gets steamed away that you may only see/feel a trace left behind as the pipes and radiators cool down between cycles. Also check all the flanges and fittings that you can see in the basement. They too can leak and, for the most part, the water steams away. If you see signs of rust around a flange or other fitting, go back to that fitting with a flashlight when the boiler is running and ssee if you see any trace of steam. You'd be surprised how much water can escape/steam away, over the coure of two or three days, from what appears to be a couple minor leaks.

Captain Who

I have an automotive mechanics inspection mirror that I've just started using to try to find small steam leaks, like from vents that don't close completely or too slowly. It works very well, especially if you clean it very well first. I've found that steam is pretty much invisible when it is a very tiny jet.

KC_Jones

Captain Who said:

I have an automotive mechanics inspection mirror that I've just started using to try to find small steam leaks, like from vents that don't close completely or too slowly. It works very well, especially if you clean it very well first. I've found that steam is pretty much invisible when it is a very tiny jet.

Steam is always invisible. If you see what you think is steam that is actually water vapor, steam that has started to condense back into water again or was never really steam in the first place. This is the reason steam leaks can be dangerous at high pressure (another good reason to have low pressure in a house).

Captain Who

Yep, when the steam encounters a temperature where it is below the dewpoint (for its given partial pressure) it condenses into visible water vapor which is basically atomized liquid water. Likewise, when the invisible steam impinges on a cold mirror (relatively), it condenses and becomes visible.

Abracadabra

What's the attached EDR of the radiators? IN-7 is 542sq.ft. of steam. Maybe you're undersized?

SWEI

Hatterasguy said:

Imagine you are in a boiler room on a ship and you suddenly HEAR the steam leak. We're talking 600 psi superheated steam at 600F. You can't see it............what do you do?

Run like hell!

Captain Who

I was going to say don't move lol.

SWEI

I'm assuming you had a vector on the sound. Lacking that, freeze. Maybe poke around with a 2 x 4 looking for a safe exit.

nicholas bonham-carter

Someone here said that a broom would be used to find a steam leak in the engine room, of the ship. They would wave it around, and the steam leak would cut the shaft of the broom off! Then they knew they had found it.
The panting of the vents occurs during the venting phase of the cycle, and it may be due to a puddle in a sagging pipe, moving back and forth alternately stopping and allowing the flow of air, being pushed by the steam towards the main vents.
What a pity our pipes are not made of Pyrex, so as to better see what is going on!--NBC

KC_Jones

I know this is way off topic, but since ships came up what movie is this line from (I am paraphrasing some). "Live steam, sleepy steam".

a2shutt

Interesting conversation about high pressure steam. Glad I'm dealing with low pressure!

I tried checking for pitch today and found it not easy. However, I found a few spots that seem pretty flat. Any tips for correcting that?

Thinking that a thermal camera would be slick for finding those bellies in the pipes.

Also, I found a few rusted streaks where I haven't noticed any leaks before. I attached pictures. Should I be concerned about these spots as far as water loss goes?

Fred

The picture of the vents looks like water may be spitting out of the vents. I'd keep an eye on that. The picture of the pipe coming down from the floor definately looks like something above that is leaking. The capped pipe looks OK.

a2shutt

Yeah one flat or even negatively sloped area was the last 5' of the main leading up to the main vents. So there could be lots of condensate there.

Captain Who

a2shutt said:

I tried checking for pitch today and found it not easy. However, I found a few spots that seem pretty flat. Any tips for correcting that?

I screwed angle iron brackets at key locations above my pipes to the floor joists. I mounted a threaded eye bolt (open it up a little with a dremel cutoff wheel so the chain can be hooked on it) in each one with nuts above and below to allow adjustment up and down and ran some chain from the eye bolt around the pipe and back to the eye bolt.

Fred

You can buy adjustable pipe hangers at most plumbing supply houses (if your steam pipes don't already have them). You can screw them into a joist where needed and repitch the main or lift a sag. Be careful not to over do it though as that may throw all your radiator runs, in that area, out of pitch. The key is to get it back to where it was originally, when th mains and the radiator runs were properly pitched.

Jamie Hall

of course, when the whole building has settled, it can get rather interesting!