Steam Boiler Overfilling

ScottKruger · January 13

I have a Weil McLain EGH-95, 400,000 BTU steam boiler that was installed about 10 years ago. The boiler is overfilling. I have had the boiler company over for repairs several times. It is not overfilling while I am observing it, but it is overfilled within 24-48 hrs of draining. This is what has transpired:

Visit #1:Technician did not see a problem. But, the Tech cleaned the McDonnell probe. Within 24-48 hrs of the visit, it was overfilled again. About to top of site glass in 48 hrs.

Visit #2: Tech installed a new McDonnell Miller WFE-24 Water Feeder. Boiler continued to overfill.

Visit #3: Tech installed a new McDonnell Miller BoilerWize FPC-1000 Low Water Cutoff. Boiler continues to overfeed. But it is much worse now. Within 24 hrs, the boiler is severely overfilled. I have two outflow valves which I opened and it took over 2 minutes before the water level even reached the top of the site glass.

2) The site glass is pretty clear, but there is about 1 inch of gunk in the bottom of the site glass. I do not know if this could be a cause.

Any ideas on what could be causing this problem?

I appreciate any help. Pictures below:

Jamie Hall · January 13

Is there a domestic coil? I doubt it… but that could be the problem.

A much more likely problem is that the bypass valve around the water feeder is leaking — or simply not completely shut. Anyone check that?

109A_5 · January 13

Hello ScottKruger,

Remove the lower sight glass valve stem and flush out the crud.

As Jamie Hall stated, unless there is some other water source.

delcrossv · January 13

Or, slow condensate return is triggering the auto feeder.

Check the bypass valve first.

EBEBRATT-Ed · January 13

There are only 2 ways for water to get into the boiler. The manual feed valve could be leaking. Or the water feeder is leaking or is being told by the low water cut off to feed when it shouldn't be. High water pressure could contribute to either of these leaking by. If so a pressure reducing valve can help. 40-50 psi is ok.

Seems like they addressed the feeder.

Now if you have a plugged condensate return line the water may return to the boiler slower than it leaves as steam. This would cause the boiler to get low on water while it is running and cause the feeder to feed. Then when the boiler shuts down all water returns, the excess the feeder fed + the water in the return that was slow to return causing a high-water level.

Also the feeder must be set up properly. See the instruction manual. There are dip switches inside.

EdTheHeaterMan · January 13

Since the last repair has actually increased the speed of the overfilling event, I might suggest that the water feeder may be incorrect for your purpose. There are water feed valves that have adjustable time delays from the LWCO actually sends the add water signal to the feeder and the feeder actually opens the valve to fill the boiler. this gives the boiler's condensate to return form the radiators and satisfy the need for additional water before the feeder actually feeds the water, Like the model VXT-24

The replacement McDonnell Miller WFE-24 does not offer that feature, but has orifices to reduce the flow rate into the boiler when the valve is open. It comes with a 2 GPM orifice installed and optional 1 GPM and 4 GPM orifices, that should be selected by the installer. Perhaps your service company should stop using the parts cannon to fix this problem and actually diagnose the problem. Ask for the VXT-24 and you should not need to pay for it, since you already paid for the McDonnell Miller WFE-24 that did not fix the problem, but actually made it worse.

EdTheHeaterMan · January 13

Also, the new feed valve was installed incorrectly, the only union is in the wrong location for the proper test before condemning the old water feed valve. So I would call the company and ask them why the replacement water feeder was not installed as the manufacturer has illustrated in this diagram.

Screenshot 2025-01-12 at 10.54.30 PM.png

Here is what is called the broken union test to determine if the water feed valve is actually leaking by and needs to be replaced.

Screenshot 2025-01-12 at 10.58.55 PM.png

If they condemned the old valve without doing this test, (and they could not do the test with the current piping) Then you want your money back for replacing a part that was not defective, did not solve the problem, and actually made the problem worse. You might start out with a question like Do your service calls have any type of warranty? Like if you use a part, how long do you guarantee that part, and is the labor for replacing the part again under warranty covered?

Some companies will stand behind the work they do, and offer to solve the problem at no additional charge. (Like I used to). other companies will just keep shooting the parts cannon and hope yo get it right eventually, and you need to keep paying for the unsuccessful repairs. (like the Company that purchased my business …Don't Ask!)

ScottKruger · January 13

https://forum.heatinghelp.com/discussion/comment/1834233#Comment_1834233

I am not sure what a domestic coil is. But your bypass valve suggestion sounds reasonable. I will check that out. Thank you

ScottKruger · January 13

Is there a washer inside the bypass valve that could be worn out ? Possibly a washer needs to be replaced, or the entire valve replaced. I will check that out.

delcrossv · January 13

https://forum.heatinghelp.com/discussion/comment/1834260#Comment_1834260

It's a ball valve, so no. If it's bad, the valve would need to be replaced.

109A_5 · January 13

An easy test, close this valve and disconnect a wire from the feeder valve to hopefully totally disable that water path, still overfilling, probably the bypass valve. If it stops the overfilling, explore the other ideas above.

EdTheHeaterMan · January 13

To do the proper test your system needs another valve and another union as indicated by the Z and Y on this diagram. (I reversed your picture to match the factory diagram more closely)

Screenshot 2025-01-12 at 11.14.02 PM.png

See my post about the Broken Union Test for steam boiler water feeder valves above. It is published by the McDonell & Miller Company in the LWCO and Water Feed literature on some of their products. It was taught to me back in 1976 when I took evening classes that covered oil burners, hydronic and steam boilers.

ScottKruger · January 13

I will check the condensate return line.

https://forum.heatinghelp.com/discussion/comment/1834257#Comment_1834257

I am not exactly sure, but I believe that both the McDonnell Miller feeder and LWCO are basically the same as the original parts from 10 years ago. Although, I do not know if the orifices are the same..but I would think that both would have the standard orifice. Note that the last repair was the LWCO, and that change caused the boiler to overfill so much more.

Also, I do not know if this would be an issue with a VXT-24, but the new WFE-24 feeder was not the right size for the existing pipes. They had to get another WFE-24 from another supplier that came with an adapter. But, that adapter was for copper. So they had to get yet another adapter (I think that was the scenario).

I am so appreciative of everyone's suggestions. It all makes sense. I have actually been billed (and paid) for both a new feeder and LWCO. I would like to think that the problem could be solved without the programmable VXT-24. Because that seems like a "work around" and not actually determining the problem

delcrossv · January 13

If the underlying problem is slow condensate return, fixing that can get rather involved.

ScottKruger · January 13

What would cause a slow condensate return.

Could this be the problem. Is this the condensate return line? The nipple is all corroded and is slightly wet underneath to the touch. Could the corrosion be blocking the return ?
To replace the corroded nipple, can just the coupling and the small 90 degree piece be removed? Or do they need to remove more of the piping — and that would be more time consuming.
I noticed two spots (about 2" each) under the edge of the boiler (on the side with all the pipes). The spots are brown and are a little wet. Note, that these spots are actually under the boiler, but just at the edge.

pictures are attached.

EdTheHeaterMan · January 13

All the pipes below the water line are called Wet Returns. It appears that you have mostly Dry Returns. Only the small sections of the return that are below the yellow lines in this illustration are Wet Returns.

Screenshot 2025-01-13 at 12.21.42 AM.png

The Wet Returns are where you can have a lot of mud and sludge build up. By opening those pipes up and flushing them out, you may find that your condensate will return faster. My guess is that those pipes have not been flushed out in over 10 years. Maybe longer.

You can also make the piping repairs you want, at the same time you have the wet returns open for flushing. P{ut a garden hose on the drain valve and connect it to a cold water line to push water in those pipes while you have that union disconnected. You can then force a coat hanger or a radiator brush or bottle brush in the low pipes to stir up that sludge. You don't want to force that sludge into the bottom of the boiler, that's why you want to take the union apart and let that mud just flow out on the floor or in a pan or bucket. It will be a messy job, but once you get the mud out, the system will work better.

In order to keep your boiler clean after that, you will want to use @ethicalpaul's ideas for treating your boiler water. Look for his videos on YouTube

https://www.youtube.com/watch?v=Bx8NryCUkng

ScottKruger · January 13

I am thinking that my first test should be to close the water feeder valve and disconnect the wire from the feeder valve, and see if it still overfills. If it does not, then water would not be leaking through that ball valve. In either case though, I still need to replace that corroded nipple.

EdTheHeaterMan · January 13

Your unsuccessful repairs may cause you to try this piping repair yourself. There are several things to consider. Some of those pipes and fittings may not come apart as easily and you may need to replace more pipes and fittings that you start out to do. That is OK. I would start out with getting the wet returns cleared out. I believe that is your problem and you can't be sure unless you actually look inside them and see for yourself.

First is to drain the boiler and drain the wet return as much as possible
Then place a plastic tarp on the floor to collect your mess.
Remove this elbow first, You will need a big wrench (24” pipe wrench or at least an 18” with a 3 ft piece of 2” pipe over the handle)
Once you have that pipe open you can stick a brush in there and pull out all the mud. You may want to stick the garden hose in there to flush out as much as you can.
Nest is to remove the leaking pipe nipple to replace or repair. You may need 2 pipe wrenches in order to hold back on one fitting as you turn the other pipe of fitting.
Once you have that apart. Do the same thing to clean out the bottom of the boiler and all those pipes with a brush and/or flushing with a garden hose.
Now that everything is cleaned out, you can put it all back together with pipe sealant or teflon tape or both. (both is better in order to get a leak free seal at the pipe joints)

If you are going to ask for professional help, then make sure someone is there to monitor the progress and that those wet return pipes are all clear.

delcrossv · January 13

That's worrisome. Possible block leak.

ScottKruger · January 13

https://forum.heatinghelp.com/discussion/comment/1834368#Comment_1834368

Yes, that does not look good.

ScottKruger · January 13

Nope. Removing those pipes is currently beyond my pay grade. Maybe in my younger days, but not now. I phoned my plumber this morning. He said he could do it, but since we are in the middle of a major artic freeze, it should be done by a boiler guy. I agree, cause the boiler will need to refilled and tested, etc. He mentioned the the joints could almost be "soldered", so to spray first with "anti-lock" stuff. He also said that sometimes if you hit the elbow the correct way, it could just break off. Third point was to make sure the replacement elbow was the same type of heavy duty pipe.

109A_5 · January 13

Personally if it was my system, I would continue to diagnose the over filling issues. As far as wet return and possible block leakage, Since the boiler basically works, I would note everything, continue to observe and wait for warmer weather since messing with it could turn into a huge disaster, fast. No heat is no fun.

delcrossv · January 13

https://forum.heatinghelp.com/discussion/comment/1834406#Comment_1834406

Agreed. Limp along until spring. This is not the time for major rework.

If you have a block leak, now is definitely not the time.

Jamie Hall · January 13

Are we still going on about that nipple? Yes, slow returns — very slow — can cause a boiler to overfill. The problem can both be tested — and fixed — by turning off the autofeeder by closing its valves.

If the problem is slow returns, and the autofeeder is off, what will happen is that the boiler may shut off on low water (good — you've tested the LWCO at the same time) or may not, but eventually the water level will recover. If the returns are really painfully slow — which is hard to imagine when they are that short — this might even take half an hour or so.

If this works, then keep an eye one the boiler water level and add water manually, if need be, from time to time. Then, come summer, when you can work on that piping without needing the boiler for a while, you can tackle that plumbing at a time when breaking something won't be catastrophic.

If you find that over time the water level does recover properly, then maybe you can go and find out why the autofeeder is adding more water than it should — and fix that.

EBEBRATT-Ed · January 13

I agree run the water manually and keep an eye on it until warmer weather.

This isn't the time

You touch any of the return piping you will probably have to replace all of it.

109A_5 · January 14

Your two wet spots (Red arrows), it would not surprise me if is slightly leaking at the drain tapping (near the Yellow arrow), since the two wet spots are on either side of the drain tapping, hopefully it is not leaking above that. This situation may have been instigated by the age of the pipe and the unsupported length of the drain pipe (Blue arrow) with the valve near the far end (leverage). This may be pipe failure waiting to happen, Kind of a bad setup IMO, I would not use that drain until you get the piping repaired.

With the presumed slow wet return, another test (if you trust the valve at the orange arrow to close again), with the boiler's water level above the Hartford loop, open the wet return drain a lot and let it drain for a bit until you see the boiler water level drop. How is the flow ? I doubt the vertical drips are plugged up, but you never know.

ScottKruger · January 14

Nope, I never trust old valves. I think that you might be correct about the water spots at your red arrows. I removed the front panel of the boiler, and those spots are outside of where the blocks are.

I hung around the boiler for about 60 minutes last night after I drained the overfilled water. The cut off activated and the water feeder turned on and filled properly. But, then about every 10 minutes, The light on the LWCO illuminated and the feeder started again. This happened about 3-4 times in a row. Within 45 minutes, the water level was already at the top of the glass. Also, it seemed that the boiler kicked on for a short time every 10-15 minutes, even though the thermostat was not calling for heat.

Before I left the building, I decided to turn off the valve above the feeder, so no water could be feed into the boiler. I drained water so that the site glass was about 2/3 fill. I returned 16 hours later and the level in the site glass had dropped about 1/3 full. I manually feed a bit more water and will check again. I do not want to damage the boiler if it ends up running with an inadequate amount of water.

A new technician is coming tomorrow.

Thank you all.

109A_5 · January 14

That seems like a lot of water loss in 16 hours, where is it going ?

AdmiralYoda · January 14

Whereabouts are you located? Have you tried using the "Find a Contractor" on here? Perhaps having a steam expert might be more fruitful than going through the HVAC tech carousel.

Also…your sight gauge looks plugged at the bottom. Unless my eyes are deceiving me it looks more like its plugged solid than a little junk. Perhaps this is causing a false reading on the gauge glass because it can't drain out?

ScottKruger · 1:25AM

Yes, it is pretty solid junk on bottom & it seems like it is getting a bit larger. Going to check that out tomorrow. Thanks

Steam Boiler Overfilling

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