Problem with short-cycling, low water, and leaks

DiegoB

reggi said:

@DiegoB
So if I'm reading this right, the VXT requires the auto feed , OR can the auto feed be turned off but yet would the low water cutoff perform as a ordinary lwco and sense low water and turn off the boiler ? This would eliminate the constant shutdown and wait to get it's "water level check" but still shut down if the level is low ?
If not turn the entire VXT off and visually monitor the waterline while it's going through it's cycle to see if it drops where you can cut it off if it drops too low in the glass..
I know what I mean but I'm not sure if it's possible or if I described it clearly, or correctly 

I know what you mean. I haven't tried this yet, but I suspect this maneuver could lead to bad things if enough water has been evaporated out of the chamber and the boiler is still firing. This is probably too risky a move for me, but I could suggest it to my plumber.

ChrisJ

Jamie Hall

The VXT isa feeder, not a low water cutoff. No problem with disabling it -- provided the low water cutoff on the boiler is working. Repeat: the low water cutoff is independent of the VXT.

Sylvain

@ChrisJ
Nice to see it is a legitimate option and how it must be sized and piped.

mattmia2

In testing with the water to the auto feeder shut off (or the wire to the feeder solenoid disconnected), watch it carefully. See if the water level comes back up to the same level after a couple cycles or if it is dropping with every cycle. The probe from the Cyclegard should shut it down before it dry fires but watch the sight glass.

Does the water bounce in the sight glass as it is steaming?

ChrisJ

Sylvain said:

@ChrisJ Nice to see it is a legitimate option and how it must be sized and piped.

I still don't think you need it but just wanted to show you there's options without a new boiler

mattmia2

If the boiler is throwing liquid water up in to the mains, it doesn't return quickly so the water level slowly falls as it is steaming then over a period of time after the burner shuts off the water level will return to the original level. Frequently this will trigger an automatic water feeder. If the feeder is working and the system doesn't leak and the water doesn't get pushed out a vent somewhere the system will end up overfilled after the cycle ends.

LRCCBJ

mattmia2 said:

If the boiler is throwing liquid water up in to the mains, it doesn't return quickly so the water level slowly falls as it is steaming then over a period of time after the burner shuts off the water level will return to the original level. Frequently this will trigger an automatic water feeder. If the feeder is working and the system doesn't leak and the water doesn't get pushed out a vent somewhere the system will end up overfilled after the cycle ends.

I have had this occur with perfectly piped NBP on a large system (266K input). The boiler capacity is fairly low..........9 gallons...........and the probe is mounted at a point that is 1/2 way up the glass. The system would trigger the feeder near the end of every cycle. I put a timer on the feeder which delays it for 10 minutes. This has proven successful.

The smaller the quantity of water relative to the size of the system, the more likely the feeder will trip near the end of the cycle. The water just does not return to the boiler as fast as one would prefer.

ethicalpaul

In my experience observing my previous boiler with a sight glass on the end of the main, it's not a matter of the water slowly lowering, nor a matter of the water slowly returning.

It's that many gallons were thrown into the main, circulating very fast, lowering the water in the boiler to the bottom of the gauge glass. It was almost instantaneous.

Have a look, but ignore most of what I was saying in the voiceover...I was very new to steam and was doing a lot of wrong guessing at that point:

https://youtu.be/WSRvvNQ5WLc

Jamie Hall

LRCCBJ said:

mattmia2 said:

If the boiler is throwing liquid water up in to the mains, it doesn't return quickly so the water level slowly falls as it is steaming then over a period of time after the burner shuts off the water level will return to the original level. Frequently this will trigger an automatic water feeder. If the feeder is working and the system doesn't leak and the water doesn't get pushed out a vent somewhere the system will end up overfilled after the cycle ends.

I have had this occur with perfectly piped NBP on a large system (266K input). The boiler capacity is fairly low..........9 gallons...........and the probe is mounted at a point that is 1/2 way up the glass. The system would trigger the feeder near the end of every cycle. I put a timer on the feeder which delays it for 10 minutes. This has proven successful.

The smaller the quantity of water relative to the size of the system, the more likely the feeder will trip near the end of the cycle. The water just does not return to the boiler as fast as one would prefer.

Which is why most newer feeders have a time delay function... use it. It's not there for looks.

mattmia2

LRCCBJ said:

I have had this occur with perfectly piped NBP on a large system (266K input). The boiler capacity is fairly low..........9 gallons...........and the probe is mounted at a point that is 1/2 way up the glass. The system would trigger the feeder near the end of every cycle. I put a timer on the feeder which delays it for 10 minutes. This has proven successful.

But if this is happening it will end up overfilled and that doesn't seem to be the case here.

Note that if there is a significant amount of liquid water being thrown in to the mains that the returns will tend to heat before the mains from this water circulating in the returns.

Can we see pictures of the ends of the mains where they drop in to the wet returns below the floor? I am not at all convinced that the water isn't leaking out in a dark corner of the basement or a crawlspace somewhere where it isn't being noticed.

LRCCBJ

Jamie Hall said:

Which is why most newer feeders have a time delay function... use it. It's not there for looks.

The 101A doesn't have a "time delay function". Some people like the older equipment that will still be reliable long after the VXT is in the trash.

DiegoB

ChrisJ said:

@ChrisJ -- sorry I've been away from the thread for a while, but I absolutely LOVE this idea! So much better than getting a bigger boiler! Thank you! I guess you make the length according to the capacity you need?

ethicalpaul

I would hate to see you implement something like this only to have the problem remain. You shouldn't need a bigger boiler or a bigger water reserve as above at all. Something else is going on.

bmma

I agree with the last comment, if you're losing as much water from the system as you indicated, having a reservoir isn't going to fix that. Assuming the VXT is working correctly and the amount of water added to your boiler indicated by that is accurate, you're losing water somewhere and you need to address that. Adding a reservoir may help to keep your boiler firing longer, but you'll still be adding water to the system, and all that fresh water is going to dramatically shorten the lifespan of the boiler. You need to figure out where the water is going.

Didn't you (the OP) mention that there are buried returns? Have you exposed those yet to see if that's where you're losing water? You'll probably spend as much installing a reservoir as you would digging up and fixing the returns.

JUGHNE

Have you flooded/filled the boiler up to the header piping and checked for leaks in the boiler.

I would wait at least 24 hours while doing this test.

If you do this the the boiler water seems to drain down, but the floor stays dry then the water could be leaking out your wet returns. I believe if leaking wet return then the water level would drop down to the Hartford Loop.

Have you ID' all the returns from the end of mains.
Show us where they drop down into the floor and the other end of them.
You said previous HO replaced a wet return and it is now good....how do you know?
And there could be another buried return teed into your "good" one.

You most likely do not need the receiver tank. I just put one on a system that has a lot of large piping and a small boiler. I was not even sure I needed it but had all the materials available.

reggi

DiegoB said:

 - this plumber isn't a big steam guy. He was a plumber I have a good relationship with, and did his best on the job. 

@DiegoB You might think about getting someone that is a Steam Professional in for a consultation ,  your plumber will know at least what needs to be done and if can do it.. No matter how good of a relationship you have with him if he doesn't know steam...he can't figure out what's wrong with the system he installed... ( if anything)

DiegoB

JUGHNE said:

Have you flooded/filled the boiler up to the header piping and checked for leaks in the boiler. I would wait at least 24 hours while doing this test. If you do this the the boiler water seems to drain down, but the floor stays dry then the water could be leaking out your wet returns. I believe if leaking wet return then the water level would drop down to the Hartford Loop. Have you ID' all the returns from the end of mains. Show us where they drop down into the floor and the other end of them. You said previous HO replaced a wet return and it is now good....how do you know? And there could be another buried return teed into your "good" one. You most likely do not need the receiver tank. I just put one on a system that has a lot of large piping and a small boiler. I was not even sure I needed it but had all the materials available.

@JUGHNE.  Yes, others had given this advice too.  When I turned off the boiler for the day and flooded it, and came back at night, the water level had actual gone up slightly and this was about a 10 hrs period.   Also, in the summer time, the water level was perfectly still and was above the Hartford loop.  So, this makes me believe that isn't the issue.  Also, the previous boiler wasn't even close to this leaky - towards the end of its life, it required some manual filling about once a month,  but that's because there were pinholes in the rear sections - I heard this was common with Weil McClain boilers.

DiegoB

reggi said:

DiegoB said:

 - this plumber isn't a big steam guy. He was a plumber I have a good relationship with, and did his best on the job. 

@DiegoB You might think about getting someone that is a Steam Professional in for a consultation ,  your plumber will know at least what needs to be done and if can do it.. No matter how good of a relationship you have with him if he doesn't know steam...he can't figure out what's wrong with the system he installed... ( if anything)

Great advice @reggi.  I think it's time to get some more folks into the house to help debug this.

BobC

Most things expand when hot so they exhibit different behavior when hot.

reggi

DiegoB said:

reggi said:

DiegoB said:

 - this plumber isn't a big steam guy. He was a plumber I have a good relationship with, and did his best on the job. 

Great advice @reggi.  I think it's time to get some more folks into the house to help debug this.

@DiegoB
Good to hear, not sure of your area but you have the best of the best right here on this forum.. where are you located ? Maybe we can suggest someone, some will Travel for consultations also .. you can  check also https://www.heatinghelp.com/find-a-contractor/
The right eyes on your system: Priceless 🤩

mattmia2

I may have lost track of this answer, but did it overfill when you had the vxt set to a bigger fill?

DiegoB

mattmia2 said:

I may have lost track of this answer, but did it overfill when you had the vxt set to a bigger fill?

bmma said:

I agree with the last comment, if you're losing as much water from the system as you indicated, having a reservoir isn't going to fix that. Assuming the VXT is working correctly and the amount of water added to your boiler indicated by that is accurate, you're losing water somewhere and you need to address that. Adding a reservoir may help to keep your boiler firing longer, but you'll still be adding water to the system, and all that fresh water is going to dramatically shorten the lifespan of the boiler. You need to figure out where the water is going.

Didn't you (the OP) mention that there are buried returns? Have you exposed those yet to see if that's where you're losing water? You'll probably spend as much installing a reservoir as you would digging up and fixing the returns.

@bmma and @ethicalpaul. I think the idea is to try to rule out one source of the problem at a time. Yes, the system is losing lots of water. At the same time, we are hitting the low water cutoff before radiators can get hot. Having seen the solution that @ChrisJ posted with the reservoir, this sounds a lot like the issue I'm having. Boiler just shuts down because all the water has evaporated and hasn't returned in time.

Having a reservoir, allows us to test the hypothesis that water is leaving through the vents ... because if the boiler is allowed to fire continuously until radiators get past 170 F, then we can see test if "hot radiators" leading to "closing vents" solves the issue.

bmma

When you're boiler is firing and and rads start getting hot, have you checked to see if you're losing any steam from the vents? If they're not working right they could be letting some steam past. Same is true of any main vents. Assuming you have main vents, when the mains get hot have you checked to see if you're losing steam from the main vents? Hold a small mirror above the vent and if you're losing steam you'll see it on glass. That would be a much quicker and cheaper way to check if you're losing water out the vents than hiring a plumber to reconfigure your piping to install the reservoir.

Jamie Hall

DiegoB said:

mattmia2 said:

I may have lost track of this answer, but did it overfill when you had the vxt set to a bigger fill?

bmma said:

I agree with the last comment, if you're losing as much water from the system as you indicated, having a reservoir isn't going to fix that. Assuming the VXT is working correctly and the amount of water added to your boiler indicated by that is accurate, you're losing water somewhere and you need to address that. Adding a reservoir may help to keep your boiler firing longer, but you'll still be adding water to the system, and all that fresh water is going to dramatically shorten the lifespan of the boiler. You need to figure out where the water is going.

Didn't you (the OP) mention that there are buried returns? Have you exposed those yet to see if that's where you're losing water? You'll probably spend as much installing a reservoir as you would digging up and fixing the returns.

@bmma and @ethicalpaul. I think the idea is to try to rule out one source of the problem at a time. Yes, the system is losing lots of water. At the same time, we are hitting the low water cutoff before radiators can get hot. Having seen the solution that @ChrisJ posted with the reservoir, this sounds a lot like the issue I'm having. Boiler just shuts down because all the water has evaporated and hasn't returned in time.

Having a reservoir, allows us to test the hypothesis that water is leaving through the vents ... because if the boiler is allowed to fire continuously until radiators get past 170 F, then we can see test if "hot radiators" leading to "closing vents" solves the issue.

What a mess. OK. But where is that steam going? Where is that condensate hanging up, if indeed it is -- and not just leaking out somewhere. I hate to poke holes in an hypothesis -- but if the radiators aren't hot, there's very little if any steam in them, and it sure isn't getting to the vents. And if it isn't getting there it isn't getting out either.

May I suggest firing up the boiler and tracing along the steam mains in the basement to see how they heat up? Even if they are insulated, you should be able to follow along with your hand (or better, and IR camera if you happen to have on) and see how the steam is progressing. Find out where it goes. For reference, 50 feet of 2 inch steam main will hold less than 0.01 gallons of water when the water is converted to steam.

That much water won't even register on your sight glass, never mind drop to your low water cutoff.

Nor cam I see a way, even with truly horrible near boiler piping, that you can back that enough water out of the boiler to do it.

I can see a leak in a drip doing it, quite easily, though. Or leaks in any one of a number of other places -- starting with the boiler.

But it's not the vents.

ethicalpaul

Everything that Jamie said, plus this:

Boiler just shuts down because all the water has evaporated and hasn't returned in time.

That's just not how boilers work, at least not in homes or small buildings. The water doesn't hang out somewhere. It flows back to the boiler. If it's not coming back in a timely fashion, the answer isn't to make the reservoir larger, it's to find out why and fix it (it can only be a couple possibilities such as a plugged or dramatically leaking return)

mattmia2

Did the water on the sight glass creep up over them when it was set to fill for a longer time (say 4 gallons instead of 2)?

JUGHNE

I see the owner/install manual hanging behind the boiler.

There may be an explanation of how the "Cyclegard" LWCO works.
It will shut down the burner every 12-15 minutes or so.
(But should not necessarily add water)
In the meantime you have lost your steam pressure.

I had this problem with a system and changed the LWCO to the "Safegard" type.
This will not shut down unless there is a problem with water level.

You mentioned you gained water overnight with the flood/fill test.
This could be slow returning condensate from wet returns that catches up by morning.

And still waiting for pictures of the end of main drops into the floor, there could be more than one.

Check the installed price of that reservoir pipe, (which will not fix your problem, IMO), show the diagram to a pipefitter for a price. Then consider the other options.

mattmia2

If a lot of liquid water is being thrown in to the mains by the boiler it will take a while for all of that to work its way back to the boiler too, that could be why the water level rose.

(my bet is still on the feeder isn't feeding anywhere near the rate it thinks it is)

mattmia2

Wait, looking at this again, the probe for the lwco is about half way up the sight glass, the probe is like at the normal water line. this would seem to be the problem.

Can anyone that knows the boiler explain why this is, like the normal condensate in the system is going to trip the lwco.

reggi

mattmia2 said:

Wait, looking at this again, the probe for the lwco is about half way up the sight glass, the probe is like at the normal water line. this would seem to be the problem. Can anyone that knows the boiler explain why this is, like the normal condensate in the system is going to trip the lwco.

Well I'd say it makes sense as the unit appears higher than the bottom of sight glass.. interesting observation..
@DiegoB how about a closeup picture and include one of where the probe enters the boiler...

mattmia2

It looks like you could tee the probe off the lower tapping for the sight glass or make a parallel tube on both sight glass tappings with a tee a little above the lower sight glass tapping for the lwco probe without danger of dry firing the boiler:

reggi

@DiegoB

THIS looks shot .. without it working... Well nothing is moving.. is there another one on the other return? ( and as mentioned earlier by a few others.. the other drop should tie into the wet return at the bottom.. I'll bet the original boiler was at least twice as high as your last 2.. How old was the Weil that failed ??



Edit.. whoops.. forgot picture 
Edit Edit... the Vent circled ⭕ upper right corner ☝️

EBEBRATT-Ed

I installed a Peerless that was like that. The lwco in the factory tapping was very close to the normal water line. We had some problems before we skimmed it. After that I thought is was questionable whether we were going to have problems but then I retired and don't know what happened. If I remember Peerless had an alternate tapping available. Thats why I like 67s event though the probes are a better option. With a 67 you get to use the whole glass of water

mattmia2

"i had this problem but i retired before i found a solution"