LWCO triggering when running

virtuesplea

&tldr; - My almost 22 year old one pipe natural gas steam boiler cuts off from a low water level when the water in the sight glass is at the fill line. Filling it up 1-2" above the fill line on the sight glass has "fixed" this problem, but the water level still falls below what I can see on the sight glass when the boiler is running. How worried should I be?

More detail
I have a 100k btu ICP steam boiler in a 2200 sq ft house built in 1921 (although the top story only has one radiator and it's valve is closed, so more like 1700-1800 sq ft). The boiler is natural gas and was installed new in March of 1997, so it's coming up on 22 years old.

I bought the house in June of 2017 and had the boiler looked at by a local plumbing company in the fall of 2017. They turned it on and recommended installing an autofeed ($2k) but otherwise said it's fine. They didn't do any of the maintenance I've since read about on here (emptying it, cleaning the sight glass, etc). The closest company from this site's list of contractors is 1-2 hours away.

Last winter I needed to add a minor amount of water once or twice, otherwise it ran fine.

This winter I started it up and haven't had any issues until this weekend. I happened to be down in the basement when it turned on and noticed the water level in the sight glass was very low. I had noticed this last winter - that the water level would get pretty low while the boiler was running. But that seemed to make sense since the water is being turned into steam and into the pipes and radiators.

But yesterday, the water level got so low I couldn't see it anymore and then the boiler shut off. The water level immediately began to refill quite quickly and the boiler kicked back on when it was about halfway to the fill line on the sight glass. The water level recovered for another minute or two, then drained rapidly and again the boiler shut off. I turned it off at that point.

This morning I checked the water level after it had been off all night. It was slightly above the fill line on the sight glass. I turned the boiler on and it repeated what it did yesterday, cutting off after I couldn't see the water anymore. I turned it off again and very slowly added water until it was about 1-2" above the fill line. This time when I turned it on, the water level again dropped, but I could usually just barely see it in the sight glass. It ran long enough to heat up my radiators and seems to be ok and not cutting out from a low water level, but it does seem to be close to that point based on the sight glass.

So my question is whether it is in fact normal for the water level to fall so far while the boiler is running? How low is normal/ok?

And while I'm here, how long do these steam boilers last? I've read 10-15 years but I've also read they basically last forever (decades) if maintained. I have no idea of the maintenance history of this one - the owner who installed it seemed to be on top of things (made many improvements to the house), but the next owner was here for ~8 years and then was foreclosed on. The house was empty for about a year and a half to two years before I bought it and moved in.

nicholas bonham-carter

If the pressure goes up because of a clogged pigtail, preventing the pressuretrol from feeling the pressure, then the water from the boiler will be pushed up in the wet returns, starving the boiler. If the boiler is switched off, then the boiler water level will return to normal. It doesn’t take much pressure to do this, so take the pressuretrol off, and check the pigtail.
This is why we feel that having a low pressure 0-3 psi gauge is so important.—NBC

virtuesplea

Thank you for your reply.

The pressure shown on the pressuretrol doesn't change much if at all from when the boiler is not running, running, or has cut off. It stays at 6-7 psi.

Jamie Hall

6 to 7 psi? Much too high -- but unlikely to be real. Either the pressure gauge is faulty, which is not unusual, or the pigtail is clogged -- a @nicholas bonham-carter suggested. Which is much more likely.

Either way, do clean out the pigtail. Since you will have it apart to clean, you might take the opportunity to purchase a 0 to 3 psi gauge and mount it on the same pigtail as the pressuretrol -- a T, a couple of elbows and some nipples will do the job -- and then you will know what pressure the boiler is really running at.

virtuesplea

I just read on another post that 6 psi is high. Here's a pic of my pressuretrol and pressure gauge.

virtuesplea

Thank you so much for your help! I'll grab a 0-3 psi pressure gauge and add that in when I clean out the pigtail. I'll update the post for future readers (I love reading this forum), but it'll be a couple of days before I can get time to do this.

Chris_L

You also need to turn down the pressure setting on the pressuretrol. Adjust the screw on the top until the "cut-in" indicator goes down to 0.5 psi, and adjust the wheel on the inside to 1.

(If your pressuretrol is set too high, that would explain your pressure reading on the gauge.)

ethicalpaul

Be careful with the pigtail...it looks like steel (it should be brass) and it may be very rusted and not want to come out of the boiler. With the boiler cold, try to remove just the gauge and blow into the pigtail to see if it's clear. You could normally try to clear it with a pipe cleaner or similar tool, but yours is more than a full 360 degree circle, so that will be difficult if it is in fact plugged.

Also the pressuretrol is connected to the boiler via a different pipe (often the pressuretrol and the gauge share the same pigtail). Can you take a picture of that view from a little farther away? Both the gauge and the pressuretrol have to have free access to the pressure of the boiler (as you probably know)

Finally, does the gauge stay at that reading even when the boiler is cold (or warm) between firings? It could be stuck.

virtuesplea

@ethicalpaul Could I buy a new brass pigtail and just replace it? Would it have to be the same shape, with more than a 360 degree circle? And should I be cleaning out the pigtail for the pressuretrol or for the pressure gauge. I'm assuming both.

I do think the pressure gauge is stuck. Even after I turned the boiler off overnight, it still showed 6 psi.

@Chris_L I'll adjust the pressuretrol also, thank you.

Here are a couple of pictures from straight on and the other side.

STEVEusaPA

Next up...skimming that boiler.

virtuesplea

@STEVEusaPA There was no maintenance for at least two years before I bought the house, likely much longer. I'm getting a crash course in boiler maintenance

ethicalpaul

virtuesplea said:

@ethicalpaul Could I buy a new brass pigtail and just replace it? Would it have to be the same shape, with more than a 360 degree circle? And should I be cleaning out the pigtail for the pressuretrol or for the pressure gauge. I'm assuming both.

I do think the pressure gauge is stuck. Even after I turned the boiler off overnight, it still showed 6 psi.

You can buy a new one and replace it. It doesn't have to do the extra turns that your current one has, it can look like the one on your Pressuretrol. Often, there is a tee and both devices are attached to the same pigtail, but two are fine--just twice the number to keep clean

Yes, check both if you can and ensure that you can blow through them. You may not have to remove them from the boiler to do this, depending on how intimate you want to get with the boiler.

The Pressuretrol one is tougher obviously because you will have to disconnect the two wires that are connected in there, but if you power down the boiler and are decently handy with wire, you'll be OK. It's just a switch with two connections.

Look for a link for a pressure gauge to buy on this forum, or if you can't find one, I can dig up a link. Likewise the pigtail, if you like. Try supplyhouse or your local parts counter if they aren't too crusty to civilians.

virtuesplea

Could I replace the two pigtails with a single one, with the pressure gauge teed off the pressuretrol pigtail? And cap where the pressure gauge is currently attached? That way I only have to maintain one in the future.

If I can replace the two pigtails with one, do I need both this higher pressure gauge and the low pressure gauge? Both teed off the same pigtail as the pressuretrol. Or is just the new low pressure gauge sufficient?

Everyone on here has already been so helpful, I can do the work of digging up the parts. But thank you very much for the offer.

ethicalpaul

Yes, you can just use the one and branch it with a tee above the pigtail. Many are set up this way. If you want to make it really easy to maintain, put a union above the pigtail.

According to code (so I'm told) you need to have a gauge that goes to twice the psi of your pressure relief valve. But I only have the low psi one because what are the odds of being there looking at it at that moment when both the pressuretrol and the prv fail?

virtuesplea

I haven't been able to clean out the pigtails yet, but had one more question. I tried to adjust the pressuretrol as suggested by @Chris_L, but the little slide lever thing is stuck and won't move. Is there a trick to getting it to move or do I need to replace my pressuretrol also?

ethicalpaul

Use the screw at the top to adjust it

EBEBRATT-Ed

Replace the pigtails and skim the boiler. Lower the cut in pressure as low as possible (the boiler should start with the pressure just above 0 with the thermostat calling.) You looking to run 1 1/2-2psi maximum pressure. Then work on air vents. Your system will work much better, quieter and save fuel.

virtuesplea

@ethicalpaul thank you, that worked.

@EBEBRATT-Ed is skimming the boiler something I can do or is it something for a pro? I've read a few threads on here that say it's something for a professional to do, but they also seem to refer to skimming a new boiler.

Unfortunately, I'm going to have to wait until next weekend to clean out the pigtails and add the low pressure gauge.

ethicalpaul

There's another setting inside the pressuretrol that is a white plastic wheel which is the "diff" or differential. Its value, plus the "cut-in" value on the front gives you the "cut-out" or the actual pressure where the pressuretrol shuts down the boiler until the pressure drops back to the "cut-in" level.

You might consider turning off power to the boiler and having a look inside. The diff should be set to 1, its lowest setting. You may see a lot of improvement just from those two settings (but definitely check those pigtails regardless!)

The other screw at the bottom of the front panel you can loosen and the top piece lifts off to see the "diff" setting.

A homeowner can skim, it's a very gentle easy process by definition, but the challenge is often finding a suitable port from which you can skim. You need something hopefully above the normal water level and in the 3/4 to 2" size range, bigger is better.

If you send more pictures of the rest of your boiler, folks can opine on the feasibility

ethicalpaul

If I may blab on some more, another cause of low water level during heating cycle is atrocious near-boiler piping. Everyone loves to see what is out there, so if you can take pictures from a few feet away showing the big pipes near your boiler, folks can tell you if their arrangement might be throwing water into your mains (which it shouldn't be doing).

See my post and movies here to see what weird piping can do: https://forum.heatinghelp.com/discussion/168004/sight-glass-on-main-shows-a-surprise#latest

virtuesplea

I am very much enjoying reading all of the comments, so "blab on" as much as you like. I think this forum has replaced reddit in my favorite internet discussion places.

I did adjust the cut-in screw this morning, but haven't opened the pressuretrol to adjust the diff.

I'll take some more pictures in a little while - I work from home, so I don't have far to go.

I do hear what sounds like water in the pipes overhead when the water in the sight glass goes down drastically.

virtuesplea

Here are a bunch of pictures.

ethicalpaul

OK those are great pictures!

Even after my short time here, I am already a better installer than your boiler installer was I'm afraid.

Your near boiler piping probably is working just like an old coffee percolator, with the steam pushing water right up into your mains. The equalizer comes off the side of the riser, and that means that instead of the steam shedding water by turning away from the direction the water is flowing (up in this case), it's way too easy for the water to keep flowing up with the steam.

Reducing the pressure and making sure the pressuretrol/gauge are seeing the true pressure should help, but that is a ridiculously insane piping setup right there.

The pros will agree or disagree with me, so wait to see what they say before you tear it out

ethicalpaul

Also regarding skimming, I see nothing really available except for the pressure relief valve port. That could be used but it wouldn't be optimal.

There might be other ports plugged under the jacket (blue shell) but those would obviously require investigation and more work to make available.

1Matthias

That's some...."unique" near boiler piping. Totally wrong, but..."unique".

virtuesplea

I was finally able to do this maintenance on my boiler. As predicted, the pigtails were completely clogged; they've been soaking for a couple of hours now and are still clogged. Luckily I was planning on replacing the pigtails anyway, so went ahead and did that (with unions) and added a low pressure gauge. I did leave the old configuration, with two pigtails.

I also made sure the cut in was at 0.5 psi and the diff was at 1. After everything was put back together, it still works!

Unfortunately, this doesn't seem to have solved my original problem, which was that the low water cut off is cutting off the boiler unless I fill the sight glass to a couple of inches above the fill line. Any further ideas?

Jamie Hall

Uh... no. That near boiler piping is pretty close to hopeless, and will throw water out. Your make do by filling a couple of inches above the normal water line is OK, but be sure not to overfill (you still have to see the water level).

EBEBRATT-Ed

Unfortunately as @Jamie Hall mentioned your near boiler piping leaves a lot to be desired.

Looks like you may have some minor leaks around the pigtails, gage glass and make up water connections. If your handy I would address those items before they get any worse.

At this point fixing the piping would be a summertime project as long as your getting heat the way it is. It's not going to run great the way it is.

Fred

Nothing else needs to be said about the ner boiler piping. It is a mess. Having said that, how much bounce do you have in the water in the sight glass when the boiler is running? If more than an inch, the boiler probably needs skimming. A lot of bounce can cause the water to drop enough to trip the LWCO.
Also, what type LWCO is on that boiler? If it is a Cyclegard, it will shut the boiler down at various intervals to check the boiler water level.
Finally, when was the last time the wet returns were flushed out? They could be clogged enough to cause slow return of condensate and that will shut the boiler down until enough water returns to allow the boiler to fire again.

virtuesplea

I was afraid the near boiler piping might have something to do with this problem.

I am getting heat; I only noticed the issue because I was in the basement. The temperature of the house stays nice and steady though.

When the boiler is running, the level stays constant into about 0.5 psi, then drains till there is about 2" of water in the sight glass. Then that creeps away. If the water is high enough not to cause a cutoff, the level creeps slowly back up. And then more rapidly back down and stays down usually until the boiler is done. I don't know if that's "bounce" though.

How could I see the lwco to find out the brand?

The boiler is about 20 years old and as far as I can tell has never had any maintenance done. I've had the house since last fall and am playing catch up. 😁😬

Fred

The LWCO is the box under the Pressuretrol/gauge with no cover on it. Is that the cover laying on top of the boiler? Does it say "Cyclegard"?
The water in the sight glass does suggest the boiler needs to be skimmed. That boiler probably has never been skimmed and when there are oils on the surface of the water, it is very difficult for the steam bubbles to break through the surface of the water. What typically happens is it then pushes the boiler water back into the wet returns, which, in turn drops the water level. I also have a Burnham boiler and they are very sensitive to oil on the surface of the water. That boiler probably does not have a skim port on it and putting one in, at this point would be difficult at best. What you will need to do is turn the boiler off, take the Pressure Relief valve (on the side of the boiler) off, take the elbow off and replace the elbow with a 3/4" Tee. Remount the Pressure relief valve on the top of the Tee and add a short nipple onto the end of the Tee. You can then use that to skim the boiler, very, very slowly. Raise the water level in the boiler until water starts to flow out of the open end of the Tee, then turn the water supply down until it just trickles out. Put a hose on the nipple and run it over to a floor drain and let it trickle for several hours. If you don't have a floor drain, you will have to use a bucket and stay with it for several hours. Rushing that process will just mean that you will have to do it over. Once you are done skimming the boiler, put a 3/4" cap on the end of the nipple and it is ready for the next time you need to skim.

It's probably a very good idea to buy a new Pressure Relief valve and replace that old one if you know the boiler has been neglected for years.

In any case, I suspect you will see an improvement in the LWCO situation. If not, you at least have eliminated one possible cause and flushing the wet returns will be the next step.

virtuesplea

Just like the pigtails, even if it doesn't fix my LWCO problem, all of this is maintenance that has been neglected and needs to be done. And I'm having a lot of fun learning about my boiler and how to take care of it.

You are absolutely right that the cover on the top of the boiler is for the LWCO. It's a Honeywell Guard Ring. See two pics below.

I'll order a new pressure relief valve, the 3/4" tee and nipple and cap. I don't have a floor drain, so I'll plan a day in with my boiler.

What about the wet returns? How do I flush those out?

Fred

I don't know if that LWCO stops the boiler, during a cycle, to check the water level or not. Maybe someone else here can answer that question.
I see at least one plug on the wet return, in your picture, near the boiler. Hopefully there is another at the opposite end of those returns that you can remove and hose or snake them out. Not having a floor drain will make that a challenge as that water/gunk will be a mess and will stain the floor.
If there is no plug on the opposite end of the wet returns, you may have to have a plumber break an elbow and install a Tee with a plug. Of Course, if you have a union somewhere on the vertical that drops into the wet return, you can just take that apart and flush from there.

virtuesplea

LMAO at the idea of unions anywhere on these pipes.

I'll try your suggestions and see what I find. The basement is unfinished, with an old and already stained floor, so I'm not too worried about making a mess.

virtuesplea

I just checked and there are two plugs, but both close together near the boiler and not sufficient for flushing the wet returns. The second is in that last pic of the first big set of pictures - it's on the ground - there's an elbow to the right and the plug on the left, facing the camera.

So I'll deal with skimming first and figure out the wet returns (and near boiler piping) for warmer weather.

virtuesplea

I wanted to update my post. I finally got around to skimming my boiler. I ended up draining the hose into a condensate pump I have for my dehumidifier that has a line that goes outside. That made the process super easy. I let it trickle for 5 hours last night and when I turned the boiler back on, it ran for about 20 minutes (starting from cold) with the water level only dropping about an inch.

I also drained a bit of water out of the bottom of the boiler - I did that before starting to be sure that valve worked before I filled the boiler all the way up with water to make sure I could get the extra water back out when I was done. The water that came out was black.

It's now running for just a few minutes at a time when the thermostat calls for heat and only running every couple-few hours. I can't wait to see my next gas bill and I can't believe the previous owners (or me last winter!) didn't do this basic maintenance sooner. Thank you guys so much for your help.

nicholas bonham-carter

That task should have been on the list of things to do for the installer, or for him to have showed the original owner how to do.
You are not alone in suffering from the lack of knowledge of many heating “pros”, and Angie’s list ”trunkslammers.”, who specialize in cut and slide, cash the check as soon as possible after leaving the job.—NBC

virtuesplea

I plan on owning this house for a very long time, but I have a notebook in which I am writing all of this. Not only when this basic maintenance is performed, but instructions on how to do so and how often it needs to be done.

I had a local, very popular HVAC/plumbing company come out when I bought the house. They turned the boiler on to be sure it ran and recommended the installation of an automatic water feed (to the tune of $2k). No other maintenance done, no other checks, no information for me.

BobC

If you can check on the boiler a few times a week do not install a auto filler - they can cause more problems than they solve. Show them the door and save the money for things you need.

You can do a lot yourself and you will do a good job because iy's your house. Since 1970 I have only called for service once, outside of yearly oil burner cleanings. The one time I did call was when the primary side burner control died, even then they reversed the tstat and primary connections on the first control (fried it). You can do most any steam work yourself but I would leave combustion issues to the pro's unless your willing to buy a combustion analyzer and learn how to use it - which i did a few years back after a tech left the burner with high CO readings.

Bob