boiler water level drops dramatically

JimFromChurch

Hi. I am a volunteer at out church. We just replaced our boiler with an 8 section Weil McLain. It is a two pipe steam system with a main condensate pit and a smaller condensate receiver/pump at the far end of an orphaned line. The boiler fires up and the water level starts to rise and bounce. About 8 minutes into the burn, the water level drops dramatically. The low water cutoff triggers and the burn stops, the condensate pump starts up. The water level continues to drop and it triggers the electronic low water cutoff. The condensate pit sometimes gets flooded with hot water (I am assuming straight from the boiler because the short timing). The system goes from 50% full to completely shut down, pit flooded, pump turns on etc in about 45 seconds.

Barely any steam is making it to the radiators. There is some banging especially after the unit shuts down. We checked the condensate pump and it seems to be working well enough. We reset the electronic low water cut off and start the process all over again. Sometimes that level doesn't drop low enough to trigger the low water cutoff and the pump refills the boiler and it starts up again.

So, it seems like some sort of vacuum is occurring that is sucking the water out of the boiler and into the condensate pit. We do have a number of old traps and strainers that have not been serviced in a long time. Our boiler guy wants to replace/service all the strainers and traps. This is an OLD system that used to have two huge coal fired boilers. Thoughts? THANK YOU!!

JUGHNE

What controls the pump in the pit? The boiler control or the pump's float.
Where is new water added? at the boiler or the pit.
Do you see a check valve between the pump and the boiler?

Jamie Hall

JUGHNE said:

What controls the pump in the pit? The boiler control or the pump's float.
Where is new water added? at the boiler or the pit.
Do you see a check valve between the pump and the boiler?

I hope it's the boiler control and not the pump's float. The pump's float should control makeup feed, if any is required.

First and perhaps obvious question: was that new boiler skimmed? If not, start right there. Thoroughly.

Second, was that new boiler's water line matched to the original water line? If not, check all your wet returns and drips and make absolutely certain that they are still wet -- even in the farthest reaches. This can be particularly problematic with condensate receivers which are vented to the atmosphere. With that system, you don't have the benefit of the boiler pressure holding water in the wet returns, and in order to keep steam out of them (and out of the dry returns) you have to have functioning traps on all the drips to the wet returns or the wet returns have to be at least 28 inches for each pound of boiler pressure below the water level in the condensate tank.

Third, come to think of it, is the boiler piping correct?

Fourth, assuming you have a low pressure gauge on the boiler (if not, put one on), what is the pressure doing? What is the pressure in the boiler when the water starts to drop? At the risk of pointing out the obvious, if the pressure is more than a few ounces, but the radiators aren't getting much steam yet, the main venting is atrocious. Now what the main venting is supposed to be is another question. It could either be crossover traps from the ends of the mains to the dry returns, with all the venting at the ends of the dry returns, or it could be main vents at the ends of the mains -- again, with venting at the ends of the dry returns.

Seabee5701

Who determined size of new boiler compaired to the 2 old huge coal fired boilers? The newer style boilers do not hold the same amount of water. Its normally much less. If there is any way to shut main steam supply at the boiler. Turn boiler on and see if water level is normal and boiler pressure comes up. If all normall, try to shut valves on radiators. Open 1 or 2 valves on radiators and see how boiler reacts. Then open 1 or 2 more, see what happens. If you only open 1/2 ofvradiators and boiler is ok, I would suspect that this new boiler is undersized.....

Jamie Hall

It is, perhaps, worth mentioning that a vacuum cannot be created anywhere that steam has not gotten, nor can a vacuum be created in a steam system with normal venting...

JimFromChurch

JUGHNE said:

What controls the pump in the pit? The boiler control or the pump's float.
Where is new water added? at the boiler or the pit.
Do you see a check valve between the pump and the boiler?

New water is added at the pit and the boiler controls the pump in the bit. There is a check valve between the pump/pit (which is much lower) and boiler. I think if the check valve were failing, then the boiler would empty when it was cold. But we are going to check the check valve anyway.

JimFromChurch

Seabee5701 said:

Who determined size of new boiler compaired to the 2 old huge coal fired boilers? I would suspect that this new boiler is undersized.....

We replaced a WM 8 section that functioned well for 30 years with another. The furnace died in the late fall (as they often do) and so we rushed to just replace what we had. I don't think the boiler is undersized. Thanks for your suggestions!

JimFromChurch

Jamie Hall said:

First and perhaps obvious question: was that new boiler skimmed? If not, start right there.
(JB) I BELIEVE SO. OUR BOILER GUY KNOWS WHAT HE IS DOING. OUR CONDENSATE SYSTEM IS OLD AND FUNKY.

Second, was that new boiler's water line matched to the original water line? If not, check all your wet returns and drips and make absolutely certain that they are still wet -- even in the farthest reaches. This can be particularly problematic with condensate receivers which are vented to the atmosphere.
(JB) ONCE FIRED UP AND PUMP RUNS, WOULDN'T THE WET RETURNS FILL AND RESOLVE THIS ISSUE?

With that system, you don't have the benefit of the boiler pressure holding water in the wet returns, and in order to keep steam out of them (and out of the dry returns) you have to have functioning traps on all the drips to the wet returns or the wet returns have to be at least 28 inches for each pound of boiler pressure below the water level in the condensate tank.
(JB) I DON'T FULLY UNDERSTAND THIS. AS MENTIONED IN MY ORIGINAL NOTE THE BOILER GUY SAID WE NEEDED TO MAKE SURE ALL THE TRAPS AND SKIMMERS WERE FUNCTIONING. MANY LOOK OLD AND NOT SURE WHEN THEY WERE LAST MAINTAINED/CLEANED.

Third, come to think of it, is the boiler piping correct?
(JB) I DO THINK SO.

Fourth, assuming you have a low pressure gauge on the boiler (if not, put one on), what is the pressure doing? What is the pressure in the boiler when the water starts to drop?
(JB) PRESSURE IS 5 ON THE BIG GAUGE

At the risk of pointing out the obvious, if the pressure is more than a few ounces, but the radiators aren't getting much steam yet, the main venting is atrocious. Now what the main venting is supposed to be is another question. It could either be crossover traps from the ends of the mains to the dry returns, with all the venting at the ends of the dry returns, or it could be main vents at the ends of the mains -- again, with venting at the ends of the dry returns.
(JB) THERE IS A VENT AT THE FAR END OF THE MAIN. I CHECKED IT AND IT IS WORKING PROPERLY.

THANK YOU FOR YOUR TIME AND THOUGHTS! ALL INSIGHTS WELCOME. IT IS A MYSTERY HOW THE WATER IS GETTING SUCKED OUT OF THE SYSTEM.

Jamie Hall

Perhaps it's a mind set thing -- but the water isn't getting sucked out, as that implies that somewhere out there there is a vacuum source. Until steam has gotten to some location and condensed, there cannot be a vacuum. Further, if that location is vented to the atmosphere, as it should be, a vacuum cannot form.

On the wet returns -- with a condensate tank, the wet returns will fill only to the level of the water in the condensate receiver.

You mention that the gauge shows a pressure of 5. That is clearly not a low pressure gauge -- at least, I hope it's not. The required 0 to 30 gauges are useless in finding what it happening.

EBEBRATT-Ed

We need pictures of the steam piping around the boiler. That's number 1.

Also, did they skim the boiler after the installation?

JimFromChurch

EBEBRATT-Ed said:

We need pictures of the steam piping around the boiler. That's number 1.

Also, did they skim the boiler after the installation?

One photo attached. I can get more
. I believe the system was skimmed but would that cause all the water to go from the boiler down to the condensate pit?

JimFromChurch

I will get more photos in a few hours. THANK YOU ALL VERY MUCH!!

ethicalpaul

I'm used to looking at much smaller boilers, but that near boiler piping cannot be right for any boiler.

Regarding the size, did they measure the radiation of the building (in EDR or sq ft of radiation) and use that to size the boiler? I know an earlier commenter said it could be undersized but that would be an extremely rare occurrence, with the opposite being far more common, unfortunately.

I believe the system was skimmed but would that cause all the water to go from the boiler down to the condensate pit?

It can cause gallons upon gallons of boiler water to be "carried over" into the steam main. And based on your near boiler piping, it seems very possible to be doing that regardless.

And all that water being in the main will "kill" a lot of steam

Jamie Hall

Honestly, if I'm seeing what I think I'm seeing, it would be a wonder if you didn't have problems. No real header. No rise to the steam mains -- and, unless it's hiding somewhere, no equalizer.

JimFromChurch

here are some pictures...








this last one shows one of the two old boilers. Note the header is capped. Sorry for it being blurry.

JimFromChurch

second and third picture show the zone valves... one for a chapel that isn't heated that much and the big one for the main parish house which is the space that is heated pretty much 24/7.

JimFromChurch

ethicalpaul said:

Regarding the size, did they measure the radiation of the building (in EDR or sq ft of radiation) and use that to size the boiler? I know an earlier commenter said it could be undersized but that would be an extremely rare occurrence, with the opposite being far more common, unfortunately.
WE DID NOT. AS PREVIOUSLY MENTIONED, WE WERE IN A RUSH AND JUST REPLACED A 25+ YEAR BOILER WITH THE SAME.

I believe the system was skimmed but would that cause all the water to go from the boiler down to the condensate pit?

It can cause gallons upon gallons of boiler water to be "carried over" into the steam main. And based on your near boiler piping, it seems very possible to be doing that regardless.

And all that water being in the main will "kill" a lot of steam

MAYBE THAT IS WHAT'S HAPPENING. IF THE WATER CAN GET 'CARRIED OVER' INTO THE STEAM MAIN, IT ONLY NEEDS TO GO ABOUT 40 FEET DOWN THE MAIN BEFORE IT TRAVELS DOWNHILL, THRU AN F&T TRAP AND INTO THE CONDENSATE PIT

ethicalpaul

Right. In a correctly-piped boiler, most (or hopefully all) the water will go right past the steam riser to what's called the "equalizer" to return directly to the boiler. You have what may be an equalizer, but the way it's piped, the water would rather just continue to the steam main. Not good. Edit: You know, it was hard to see, but there may be the general correct path of steam on this one...but everything is very tight vertically.

Here is the picture where I think everything can be seen. I see two steam supplies to a very low header, to an extremely short main riser. The equalizer is a very dramatic size reduction, water could be backing up there and getting forced into the main.

https://us.v-cdn.net/5021738/uploads/editor/5m/qozis6au0dqo.jpg


I wonder what that boiler's installation manual calls for. Do you know the model number and size of it?

ethicalpaul

Here's a general idea. This is from a great document that Peerless publishes called The Color of Steam. It can be found here: https://www.peerlessboilers.com/wp-content/uploads/2018/01/OnePipeSteam.pdf



I'm nervous about the "A" dimension on your boiler too. As you know it's a big boiler and these things are critical, especially with a condensate return pump I bet. Your boiler's manual will have all the requirements in it.

I'm also nervous hearing about your zone valve. Because when the zone is closed, none of that radiation is available to the boiler, effectively oversizing the boiler even more. Does the boiler cycle on pressure, or does it run itself out of water before that can happen?

Your church should have someone compare the manual against what was done and decide how to proceed.

PS: in at least one way, you have an advantage with that open system. You can see when there is dramatically too much water appearing in the main, because it all gets dumped into your pit. Most people here have no way to see how much water is getting sent to the main.

Seabee5701

It goes off on low water.......existingnpiping abd boiler too small

EBEBRATT-Ed

@ethicalpaul

It's a pumped return so the dimensions don't apply to the returning condensate.

After studying the pictures the orientation is correct two risers then feed the steam and then the equalizer....that is correct.

Does he have the header 24" above the water line.....it's close but I don't think they have it.

Don't usually go for drop headers but this is a job that could use one.

This is one job that needed some creativity with the pipe fitting and the boiler location.

The pictures are hard to make out.

If you look in the second to the last picture it looks like there is room above the boiler to run the risers up high make a header, drip the header and feed down into the steam take off. I think the risers ar 5" and the main steam line 4"

neilc

why are you running up to 5 psi ?
can we get a closeup of the 2 Ptrols?

JimFromChurch

I can get you more pictures. And if I could figure it out, I would take a video and show you how fast the water level drops and what the gauges say. Let me know what you want. Geez... I wish you all were local... I would buy you all beer and christmas gifts!! Thank you SO SO MUCH for your insights.

EBEBRATT-Ed

@JimFromChurch

Where are you located? Did you try" find a contractor" on this site

neilc

pigtails and water seal clean and clear back to boiler ?

Seabee5701

If water goes out that fast you are exceeding the capacity of what the boiler can supply.....

nicholas bonham-carter

When water disappears very quickly, I think it is not due to evaporation, but rather water being pushed into the wet returns by pressure. Often, there can be a horizontal element in the dry returns, which can absorb a lot of water as the level rises, and that section becomes wet.
How many ounces are showing on the gauge, when the water level moves downwards?—NBC

Steamhead

Was the old near-boiler piping welded like that? If so, that contributed to the previous boiler's failure.

Does the burner have low-high-low firing, i.e. can it fire at more than one level?

kevinj_4

Steamhead said:

Was the old near-boiler piping welded like that? If so, that contributed to the previous boiler's failure.

Does the burner have low-high-low firing, i.e. can it fire at more than one level?

Yep, they require a lot more swing joint that.

And I believe threaded fittings for the couple joints out.