Utica PEG 187 steam boiler water level drops when the burners shut off

sgwills

Boiler has been cleaned and the returns flushed, after the boiler has been running for an hour and shuts of the water level drops and the LEWCO kicks in and over fills the boiler. What would cause the drop and how can i resolve it?

neilc

well let's start with a picture of your boiler,
show the sightglass, controls, and the piping above to the ceiling,
what pressure are you set to?
and what pressure do you see as it shuts off ?
how much up and down movement in the sightglass?
Inches or quarters?
and another picture of the return piping into the boiler,

sgwills

Morning and thx for the response... attached 2 older pictures will post more in a while. Replaced the mains vents last year, do not see any pressure on the gauge when i shut it off. The level drops then slowly rises but the LWCO kicks in before the level rises enough. The boiler is a 2004 and this is a recent problem

sgwills

Just took these, had a guy add squick which i left for a few days then drained again and added 8 way in case it was PH problem.

Jamie Hall

The drop may possibly a slow return combined with a slow opening vent -- the two together could cause the pressure in the boiler to drop into a slight vacuum -- and the slow return would be holding water back.

The easiest thing to do, if your water feeder has the option, is to increase the time delay on feeding water. No reason for it to hurry, after all!

EBEBRATT-Ed

I would suspect the boiler is going into a vacuum. When the burners shut off and steam out in the system condenses rapidly 1700 x the volume of water the slightly lowering pressure causes the water in the boiler to rapidly boil and the water level drops. Sounds like you vents may be water logged not letting air in fast enough. Adding a vacuum breaker or a reverse check valve near the boiler may help.

I would be cautious about the chemicals you use. Too much can cause other issues

You need to get a blowdown pipe on that relief valve.

What I would do is remove the relief valve and put a tee on the nipple coming out of the boiler. Put the relief valve on the top of the tee with a blow down pipe on it

Put a nipple and a 90 degree elbow in the branch of the tee with the elbow looking up. Put a long nipple at least a foot in the elbow with a vacuum breaker on top

neilc

I should ask my pressure question differently,
what is the highest pressure you see when the boiler is and has been firing for that hour ?
any hissing vents ?

was the pigtail checked for clean and clear during the recent service ?
they tend to clog up, especially the steel ones you have,

that safety valve should get plumbed down to 6 inches off the floor

if the pigtail is clogged and the boiler is building pressure, you could pushing water out of the boiler back into the wet returns,
you may not, would not see the pressure on the gage because it is past the pigtail, if piggy is clogged.

also thinking that boiler is big enough that it should have been piped with 2 risers, and you're throwing wet(ter) steam up into the system,

sgwills

Thanks guys... the Utica installation shows 2 pipes but i am guessing this boiler was a replacement to an existing system as the house was built in 1930. pigtail was cleaned last year but i will pull it again, i may add another low pressure gauge also. I am not getting hissing and do not think it is pressuring up just going into vacuum on shut down (does not happen all the time so maybe also the main vents need checking) Will fit the blowdown with the vacuum break as i feel that will fix the issue or am i just putting a band aid on it?

neilc

if you're adding that vacuum breaker as Ed suggests above,
add yet another tee and your low pressure gage up there
also

sgwills said:

Thanks guys...
Will fit the blowdown with the vacuum break as i feel that will fix the issue or am i just putting a band aid on it?

the safety valve, correct?

sgwills

Yes blow down on the safety valve with a tee to the vacuum breaker... could you recommend a good reliable vacuum breaker?

ethicalpaul

A Utica with both supplies piped is the rarest of endangered species. It’s like every Utica guy had his hand resting on 1/2 of the installation diagram 

neilc

yeah, the half with the skim port Tee

EBEBRATT-Ed

@sgwills

@Tunstall Associates has vacuum breakers.

You can also use a swing check valve. Get a good quality Y pattern one and make sure it is level horizontally. 1/2" or 3/4" is fine.

Steamhead

sgwills said:

Thanks guys... the Utica installation shows 2 pipes but i am guessing this boiler was a replacement to an existing system as the house was built in 1930.

That's no excuse for improper piping. This boiler needs 2 risers to the header, and the header should be 2-1/2". Period.

sgwills

Update... the vacuum breaker did not solve the problem, flushed the wet returns and the boiler but the water is still surging and after about an hour the water is sucked out of the boiler and it shuts down. Any ideas how to proceed? If i turn off the LWCO feed it shuts down and the water returns and fires up again

ethicalpaul

I was misled by your original posts which seemed to indicate that the boiler shut down and then the water level dropped.

So what is happening is the boiler is running, then at some point the water level drops, then the LWCO shuts down the boiler?

There are only two possibilities that I can think of now that you've cleaned and checked the returns:

1. water is carrying over into your mains due to inadequate near boiler piping (this would start happening as soon as steam generation began in earnest)
2. water is being pushed backwards out the return due to high pressure in the system (this would start after radiator vents closed and system pressure started rising)

Since you report that it happens after an hour of running, I think your pressuretrol isn't seeing the system pressure and that pressure is rising to the point that it pushes the water backwards out of the boiler and into the wet returns (option 2 above). It wouldn't surprise me if some water shot out of your main vents at that point.

Have you cleaned the pigtail yet? Can you get a low pressure gauge on it to be able to monitor the pressure better?

sgwills

So after about an hour the water then slowly drops until the LWCO shuts down the boiler and then feeds water. If i shut of the feed and let it stand the water returns in about 3 minutes and the boiler will run again for about 20 minutes and the cycle happens again. I cleaned the pigtail and checked the pressuretrol and they are both good and i also opened the safety valve when it happened and released any pressure in the boiler but it still emptied? I changed the main vents to a Hoffman 75 on one and 2 Groton #1 on the other but still happening. Would over firing on the boiler push the water out?

sgwills

... additionally the boiler is still surging after adding squick and then draining 2 times. It surges about 1 1/2” total, could that be the problem and would over firing also cause the surge and potentially wet steam? Boiler has been running for 14 years with existing piping so why would it start now?

clammy

Unfortunately no provision where made when it was installed to access both the water side of the boiler and the small section of return piping . Has anyone ever remove the return boiler plug and flushed the boilers return passages . Usually a tee is installed both of the supply piping for skimming and the return nipple exiting the boiler so the return can be flushed .You may have a decent amount of mud and rust built up blocking the return piping you would be surprised how much garbage builds up especially after 15 years . I ve seen Utica s water lines go side ways from being very dirty and also having a decent pipe leaking in a crawl space . I think I would flush that mix of chemical out of the boiler ,it would be nice if you had a skim port you could flush the boiler out section by section from the top . Then take it from there make sure pigtails clean and install a low pressure gauge and possibly a vacuums gauge . On a side not how are are your radiator vents and are any of your steam main insulated or are there bare in a cold basement . Peace and good luck clammy

sgwills

I have flushed the returns but not under pressure, I installed a vacuum break and a low pressure/vacuum gauge. I still feel that it is over firing but not going to screw with that, will have a steam guy here Monday to check the burners. Need to get it to stop surging as that is probably causing this

sgwills

I have 2 points to flush out the returns 

Jamie Hall

A few thoughts. First, it sounds like a slow return somewhere. The real problem is that it's very difficult to see a slow drop when the water level in the boiler is bouncing, but if it comes back in a few minutes after the burners shut off it the water had to hanging somewhere out in the wilderness. Second, do you have an accurate low pressure gauge located above the water line? What does it do? How does it vary over time? And third, for the moment anyway, when the water appears to start dropping slowly, what is the pressure doing? Is there a simultaneous (or nearly so) change in pressure? Which way?

neilc

I don't think that squick is doing you any favors,
you have a pretty purple water line there.
Try dumping that squicked water and just running straight water.
make sure the boiler is cooled down before adding the new water, open your feed s l o w l y

clammy

Have you took a look at the burners visibly while the boiler is firing . Have you drained the boiler completely and flushed it good until there’s just water in the boiler and then re fire and see what goes on ? The main reason for the vacuums being produced is the lack of open venting again are you’re radaitor vents and main venting working properly or working at all . Having steam mains uninsulated and in close to outside ambient temps will produce vacuums in a system in which the venting nil . You should undo the union below your Hartford loop connection and flush out the return to the boiler , if that pipe is clog there will be no equalizing and water will be forced by pressure up into the main until the lwco cycles and it will repeat and repeat . Peace and good luckclammy

motoguy128

Being a little over fired probably isn’t the cause of the surging. Boiler needs skimmed and incorrect near piping makes it worse. It would just make it a little less efficient wasting fuel and make a little more steam.

I’d focus on the wet returns. When I pulled out my old boiler, 35 years had a 2-1/2” return about 50% blocked. New install has tees for every elbow on the Hartford loop with drains on the bottom. I drain out a cup or so from each when I blow down the LWCO.

EBEBRATT-Ed

@ethicalpaul
Yeah, that's what I thought that the water line was normal until the burners shut down