It started off with a leak in a lower seal of an end section.

Double D

This Weil McLain LGB 11 with 2-2” & 1-1-1/2” zone valves has its burner cycling off the pressuretrol set at its minimum settings. The thermostats only operate the zone controls. I have not totaled the radiation in the building yet but after a walk through I have no reason to believe the boiler is grossly over sized and I can always put the Lo-Hi-Lo fire option to work. There are several leaking radiator valves. When I fired the boiler it dripped pretty good until it came up to pressure then stopped. The 2” zones are feeding 2-3” mains each. The 1-1/2” zone is feeding a 3” main. One of the 2” zones and half of the other 2” zone is vented through the boiler feed tank vent and a Hoffman 75. The other half of one of the 2” zones is vented through a condensate return pump vent and the 1-1/2” zone feeding the 3” main has a Hoffman 75 on the dry return. There is no throttling valve on the boiler feed line and the Hartford connection is the length of a shotgun barrel. It appears someone decided they needed to raise the recommended operating level of the boiler, possibly in an attempt to prevent water hammer in the equalizing line? (Which BTW, did not work) or to compensate for a tilting water line? The system appears to be the remnants of a Bishop and Babcock vapor vacuum system. There is much more to list, some of the pictures speak for themselves, but just with the opening it’s one of those jobs that makes you say “Let me go to the truck and get a pencil” Then you drive away.

newagedawn

its amazing the abuse a steam system can take

Steamhead

I've seen this failure mode a lot with LGBs. I'd go with something like a 5-88 or 10-80 next time. And rewire the zone controls so the boiler only runs on a call for heat. We've cut fuel consumption by up to 35% in several such buildings with this change.

JUGHNE

Our high school has a 1,007,000 input 1954 fire tube steamer.
It run on constant pressure of 7 PSI (got that down to 2.5psi) 2 zone valves that didn't seal completely. A lot of open windows and rooms adjacent might run their window AC.
Rewired as Steamhead advised. However from a cool/cold start the old girl had a lot of labor pains and condensation issues.
I added a temp control probe in the lower water level to keep it hot enough to prevent the cold start issues.
Can't confirm the savings (campus metering a lot of load) but there had to be some as it prevents overheating.

Double D

I was able to find where they grouped the end switches from the 3 zone valves. One of the 3 has an end switch that doesn't break when the zone is closed. This boiler has been operating this way for at least 1 heating season and possibly more. The boiler is only 4yrs. old. At this point the only solution is to replace the gaskets or gaskets and sections if needed.

Although the system has a boiler feed tank, none of the system vents into it. At the top of the grouped dry returns from one of the zones there is 1 Hoffman 75. One of the zones is vented through a condensate return pump located in a low basement under the church. The 3rd zone has 2 grouped dry returns vented with a Hoffman 75. That's about it for venting.

The near boiler piping appears to be close to the minimum required by Weil McLain with the exception of the very long nipple on the Hartford connection. Behind the insulation there is a completely welded header.

I have much more to say about what appears to be going on with this system but I would like to hear others thoughts.

Jamie Hall

Didn't read this one all the way through the first time it came up...

Couple of thoughts -- one you know already, and that is you need more venting on this system. The other, though, is much less obvious: those zone valves feeding into much larger downstream mains aren't doing you any favours at all. Saturated steam is a very queer beast -- and one of the gotchas is that where it expands after going through something like a reduced size zone valve it also condenses. A lot. At the very least this will delay the response on a call for heat in the zone. At the worst, depending on a whole raft of things, it may prevent any significant amount of steam from getting through at all.

And I know that full port powered ball valves in those sizes are not cheap. But... it's what is needed.

Double D

Somebody went out of their way for these 2" zones. I don't run into undersized to often. The last one I saw was a 1-1/2" on a 3" main. The owner finally gave the go ahead to change it out and later told me he was glad he did it.

The Steam Whisperer

The only way to know if the zone valves are undersized is to run the numbers to be sure that you're not getting the issue that Jamie is talking about and can properly serve the radiation. The calcs are a bit complicated, but not that bad. I've got 2 inch zone valves that feed 3 inch mains that are not a problem. They are serving about 350,000 btu/hr of convectors and radiators and should need only about 2 psi at the boiler at full load.

The important thing I've found (in some cases) is with multiple zone valves on a single system is that you keep the pressure drops reasonably consistent across the valves so the steam doesn't favor one zone over another. I needed to install a 1 1/4 inch steam cock in one zone at my church because it feed a steam/water heat exchanger ( that feeds a in slab floor system) that would completely draw all the steam from the boiler when it came on. The slab only needed about 100,000 btu /hr but could suck up about 1, 500,000 btu/hr the first hour the zone valve would be open and then gradually water temps would rise cutting down steam use. Balancing the steam usage of that zone has allowed us to run only 800,000 btu/hr of capacity instead of 1,600,000 btu/hr of capacity and provide better heating of the building and recover from 20 degree setbacks ( the slab area is kept near full temp all the time). I did have some concern about the condensing of the saturated steam going through the mostly closed steam cock, but there hasn't been a problem. The 2 inch zone valve on the 2 inch main feeding that heat exchanger is way oversized.

Double D

I was able to put an end to the boiler cycling constant with the zones closed. A quick check of the low voltage wiring led me to a bypass switch.
Thank you all for the input on zone valves. At this point in time there are other issues with this system that need to be dealt with first. New zone bodies do not appear to be in the budget. I still need to do a rad survey. The 1-1/2" zone heats a small chapel with very little radiation. I don't like the idea of the thermostat cycling the boiler to feed just that zone so my thought is to just have the thermostat open and close the zone and eliminate its ability to cycle the boiler. The boiler appears to be oversized but that's too late to rectify now. System venting appears to be straight forward with the exception of some wall hung radiation in the basement.

The Steam Whisperer

With that LGB, just do what I do with nearly l every one I come across, Pull the hi fire wire and let it run on low fire only. Only about 1 in 20 need high fire to properly fill the system especially the newer LGB's that run about 60% of capacity at low fire ( the old ones ran about 50%, but tended to run rather high CO).

Double D

I didn't think of running it on low fire only. Will running on low fire create a soot build up? I will be doing a rad survey soon but looking at what's there, I'm looking at a grossly oversized boiler. I ran the boiler with only the largest zone open. With the Hoffman 75 removed and virtually no load on the building. On low fire the boiler was able to trip the Pressurtrol on its lowest setting but it took some time. On high fire it did it in seconds. I still have some major issues with venting on that zone. At the time I ran it, I don't think I had anything moving through the basement wall hung rads. Operating on low fire is definitely worth trying. Thank you!

The Steam Whisperer

Never had any soot buildup or condensation issues The boiler is designed to run high/low. Low fire combustion is clean, especially on the newer models, it just runs rather high excess air, so the instantaneous efficiency isn't quite as good, but running longer cycles improves overall efficiency, so they probably at least balance out.
I would also expect you should get longer life out of the unit.... the sections are not heat stressed as much and do not get thermal cycled as much. And the plastic gaskets between the sections are probably kept cooler, extending thier life. With running low fire the last 6 years or so, we've been able to stretch the life of some of these LGB's to about 24 years.... at least on the single riser units that don't have the extra stress of welded headers. Dual riser welded header LGB's typically fail at the gaskets in about 14 years.

Double D

@The Steam Whisperer Thank you so much for your input. If you look at my pics you can see someone raised the water line on the boiler. When I put the boiler back together would you recommend setting the heights on the LWCO & pump controller like the manual shows? Do you think the welded header was a contributing factor in the end section gasket failure? I have several reasons why they think they needed to raise it but with no ability to ask, I can only guess.

The Steam Whisperer

Setting the water line really high will contribute to water carryover, so I would set it back down to the normal level. I wouldn't think the welded header would be the primary cause of the gasket failure. Its when there are 2 risers that it appears to cause much earlier failure than I believe should happen.

JUGHNE

I work on a church with 2 IN8's.
The sight glasses were raised with a 90 and tee to add the second manual reset pressure switch.
I believe that then boiler feeders were added with that new level in mind.
The boilers were so overfilled that when the pop off was opened water would come out.
There was a lot of bad history with this install and water leaving the boiler was one of many problems.

Double D

2-1-1/2" feeds capped off, 2-3/4" returns capped off leading to individual crossover traps still connected to the dry return. 2-4' wide registers, one in the basement and one on the first floor, both high wall. Whatever is inside the duct appears to still be there. Some type of fresh air unit that used to warm the air coming in from the outdoors?

Danny Scully

You don’t think it was an indirect radiator @Double D?

Double D

When I go back I'll look into it a little deeper. The trap side is still connected to the dry return with tees passing through the outside wall possibly leading to an access door with control valves. I can see a small door (12"×12") but it's painted shut. I'll probably disconnect the traps and plug the dry return. At one time everything was connected to the steam system, including a small house behind the church which had steam lines going underground and a larger home connected to the church. I recently found the abandoned underground return line from the attached house.

Jamie Hall

Watch out about disconnecting the traps and plugging the dry return -- they may be essential to system venting.

Double D

They have listened to hammering in the smaller chapel for 27yrs. At least 2 times in that time period the service contractor was asked to see if there was something that could be done to make it stop. His first attempt was to change all of the traps in the building. After they finished, the area still hammered. As it turned out, it was an old Webster 273-T with a float filled with water. I ended up replacing it with a Barnes & Jones FT2015-3. Later I noticed Barnes & Jones makes a rebuilding kit for it.


And speaking of churches with indirect heating, look what I came across in the basement of the main church now heated with cast iron radiators.

Double D

@The Steam Whisperer Just an update on this one. We hit a stretch of bitter cold days. The building is doing just fine on low fire.
@Jamie Hall As I suspected, those traps I removed were still connected to the return side of 2 school pin indirect heaters. The supply side was already disconnected and capped. One of the traps and its piping were plugged solid.