Major System Leak & Water Feeder Won't Shut Off

mantupsj

Hi all: long-time lurker, first-time poster. Before I get to my questions, just wanted to say thanks for all you do here — I've read Dan Holohan's two main text books and have also found so many answers on this forum. So thank you.

We're on a single-pipe steam system in a three-apartment building in Chicago. The first problem is that our McDonnell Miller 101A auto-feeder won't shut off. The electrical connection seems to constantly be calling for water, which then backs up into the returns if left alone. I had to close the valve that supplies the feeder and supply by hand periodically. This led to me discovering a much more serious problem:

Our boiler, a Dunkirk D249-400S, is using its entire water capacity (at least until the LWCO shuts down the power) every time the system runs which means I have to feed by hand after each cycle. Obviously this indicates there's a giant leak somewhere — but all the radiators, valves, and vents seem well sealed. There's no sign of major water from inside any of the walls. And when it's not running, the boiler holds its water just fine without the level dropping. My hunch is that there might be a break in the returns? Unfortunately, they're buried in concrete and would be extremely difficult to uncover. I know that new water after every cycle is bad, bad, bad for the boiler and will cause it to fail prematurely. Because the water feeder was working fine before, I have no idea how long this has been going on.

Here are my preliminary questions:

1. Is there any way to investigate the leak without jackhammering up the foundation?
2. Is it likely that the overfeeding issue is because of a problem with the wiring/sensor, or because of some sort of gunk the strainer or cartridge?
3. Will the water feeder need to be replaced, or do you think it's possible to resolve the issue through maintenance?

Thank you again in advance. This feels like a serious issue, and though I've been studying up in an effort to fix whatever I can myself, I'm worried that this may lead down a very expensive road.

Steamhead

Does any water leak out of the boiler when it overfills?

Jamie Hall

On the automatic water feeder, there are two main possibilities: the solenoid valve in the feeder may be hung up open, or whatever controls it may have either a failed switch or, if it's a float type and hasn't been blown down, have had the float stick down or the float may have sunk. All that should be replaceable or repairable by a competent tech. with little hassle. I might add that if whatever controls the feeder is also your low water cutoff, and that is working properly, it's most likely the valve in the feeder.

On the leak -- it's most likely in one of the returns in the concrete, but there does exist the possibility of a major leak above the water line in the boiler. Unhappily, if there is no king valve on the wet returns, the obvious way of finding a boiler leak -- by flooding it to the header -- won't work. On the other hand, a boiler leak may be suspected if you go outside and look at the chimney when the boiler is really cooking along. If you see nice plumes of white smoke (actually steam)... there's your problem. If there's a drain valve on the wet return side of the Hartford Loop, you can check the returns up to a point -- after the system has shut down, lower the boiler water level to just below the Hartford Loop and wait perhaps 15 minutes. Half an hour would be better. And then check if there is water in the wet return.

MilanD

Well, as to water feeder it's either lwco feed switch that's faulty or a stuck solenoid on your water feeder. Tech should be able to diagnose this or you can check it with a continuity meter.

As to water making it into the returns with the water feeder on continuously, and by you not mentioning it, please clarify: does the boiler also eventually flood or does the water just back up into returns? In case that the boiler does not flood, yoir returns are definitely rotted somewhere to a point of losing the entire makeup... I would also check if the boiler is rotted by flooding a lukewarm or cold boiler. You'd need some kind of service valve on the return and before the Hardford loop, to be able to isolate the boiler. 

Which takes you to water not making it back to the boiler after the heating cycle and you having to fill it each time. Yep, your buried return is not just leaking, but it's probably completely rotted out, otherwise at least some water would make it back to the boiler.

You can use the FLIR thermal camera to locate a leak as the system is running. Then you can decide if to repair that one spot or replace all of it. As mentioned above, you are probably looking at replacing all the returns as your best option for a long term solution. On the cheap, you can try finding and repairing the spot that's rotted, but expect it being bad enough that more leaks will be coming.

Your full replace choices will be to make the pipes run along the floor if you don't want to have them dug out, or have them dug out but then line the trench in some fashion, perhaps make a concrete through, then lay the new pipes inside it, and then cover with a grill of some sorts, or metal planks. Or abandon the current location of burried returns and just dig and burry a new return, with or without making a trough. Just an idea.

Or you can install all dry returns and condensate return tank with a smart feeder (one connected to the water level on the boiler, rather than pumped on the level of the condensate return tank). This will require some F&T traps too, or piped tall p traps to separate steam from dry returns. F&T will require a bit more maintainence later on. All will be dependent on your basement setup.

All this is a job for a pro with appropriate tools and manpower/womenpower/personpower. I'm sorry you're having to deal with this - def not fun, but can be an interesting covid19 project management distraction.

EBEBRATT-Ed

@mantupsj

I don't think your problem is the water feeder as you say you have to manually feed the boiler all the time.

It.s one of two things.

Your boiler has a hole in it above the water line. Shut the boiler down and when it is cool fill it up above the top of the boiler until the supply pipe is cold then shut the water off and let the boiler sit for an hour. If it leaks water will be on the floor

Or your wet returns are leaking under the floor (which is more likely)

But do the flood test first. If the boiler is not leaking then you will know it's the wet returns.

You can probably have the return lines run on top of the floor or you could install a condensate pump

SteamingatMohawk

A FLIR camera is pretty expensive compared to a simple infrared thermometer. It doesn't have the whiz-bang capabilities, but leaves cash in your bank account.

You don't have to spend a bundle

https://www.homedepot.com/b/Infrared-Thermometer/N-5yc1vZ1z1180y

retiredguy

I have found, under the concrete floor return leaks by removing my shoes and socks and walking on the concrete floor. The concrete above the piping should be warm to hot but it should stay near the piping. If it flares out say into a pool then that is a good indication of a rotted pipe. That is how we did it in the 1960's and 1970's.

That said, if you have one bad (rotted) return line under the floor I would bet all of them are bad and should be replaced. If that were my job, I would probably do as @MilanD wrote and install dry returns and F&T traps that dump into the smallest condensate tanks available and run the discharge over the ceiling into the boiler. I have done this many times in large buildings like schools and hospitals. The tanks can be mounted below the ground, under stairs, in cupboards, and etc. This can all be fixed with a good boiler service company with a piping shop.

EBEBRATT-Ed

@retiredguy

Not only walking around with your socks on, I was told to get a cat and turn him loose in the basement and he will lie down on the warm spot

mantupsj

Hi everyone, thanks so much for your advice. I knew you'd come through! (And sorry for my long delay – hectic week at work.) I chuckled at the bit about the cat @EBEBRATT-Ed.

Nice, too, to see @Steamhead from All Steamed Up here — Gordon's YouTube videos have been a huge inspiration to me as I endeavor to learn a bit more about these pesky McDonnell & Miller No. 101a and No. 67 devices. To your question, the boiler does not seem to leak when overfilled.

I checked out the returns with my infrared thermometer as recommended by @retiredguy and there does indeed seem to be a dead-end / heat-pool under the floor.

I'll admit I'm unfamiliar with a dry return / condensate tank system, but I'll do some research. A complicating issue is that this boiler lives in a "cave" — a 6x6x7 hole in the basement floor — and there are three radiators on the basement level, which I assume is why they buried the returns to begin with, to get them out of the way. I'll try to post some pictures and make a quick sketch of the layout.

In the short term: I'd like to get the water feeder issue solved, because as bad as it is to be losing the water in the ground (and bringing new water in) we're in the middle of the heating season and I can't keep filling it manually in the middle of the night when it gets down into the teens and single digits. Based on the dismal state of the near-boiler piping and returns, it seems like that might be a job for the summer months.

Per @MilanD's diagnosis, I think I've determined that the problem is with the electrical switch or the sensor/float. When I cut the power, the red manual feed button pops back up. I also disassembled the strainer and cartridge and cleaned out the gunk (pics attached), which didn't solve the problem. Basically, it's constantly calling for water, even when the boiler is filled to capacity. Can this be adjusted, or will I be forced to replace the feeder and/or LWCO entirely?

FWIW, the water runs just about clear when I blow down the LWCO, as opposed to the "weak tea" color that seems to be common.

mantupsj

neilc

edit = it's a 67, read that now,

post a picture of the LWCO,
if it's a float type the float could be flooded and sunk, or jambed down by gunk, and calling all the time,
If it's a probe, it could be sunk in gunk, and need cleaning or replacing,
cleaning or replacing would apply to either case.

EBEBRATT-Ed

Sounds like you need to replace the McDonnell Miller #67 low water cut off.

They can be taken apart and cleaned and parts replaced. But MM recommends replacement every 10 years. They are a safety control and right now your relying on that control.............it's the only device saving the boiler from burning up.......especially with the leak you have.

If it was me I would get someone in their to replace the returns. It needs to be done regardless of the near boiler piping or replacing the boiler.

You don't want to lose the boiler in mid winter

mantupsj

Thanks, @EBEBRATT-Ed. A malfunctioning LWCO freaks me out for the reasons you guys have mentioned – if I were to replace it with another #67 I'd have half a mind to attempt it myself, but I reckon I ought to look into newer models and have a tech handle it since it's such a sensitive piece of safety equipment. Model suggestions welcome.

I'm trying to decide how much money to sink into this knowing that the boiler is likely to die sooner based on how it's been treated. I took the building over from a neglectful owner who didn't so much as change busted air vents.

Totally agree regarding the return piping. I have a hunch this is going to take multiple diagnostic visits, but cry now or cry later, I suppose. Two apartments, each with a radiator or two) have doors into the utility room, and I'm trying to imagine how returns could be run from them.

Here are some pics of the "cave" and boiler configuration — get ready to groan.

The near-boiler piping is in bad shape, and the controls are mounted on the opposite side, which requires me (or the frustrated tech) to shimmy into a tight squeeze in that small 6x6x7 room. Also interesting to note the vents in the first pic, which are attached to pipes that are just barely visible as they run through the ceiling of the cave.

mattmia2

So those are dry returns unless there is some sort of false water line arrangement somewhere else which means they only need to be below the radiator/pipe they serve, generally speaking.

EBEBRATT-Ed

@mantupsj

It's ok to use copper on wet return. The near boiler piping is a mess but I have seen worse. The returns are going to have to be fixed anyhow for a new boiler so why not split the bill upinto two lesser bills.

I would put another MM #67 on their quick and easy. They have been made for probably 70 years or more. Not that hard to change, if your handy you can do it. Just make sure it's wire right and shuts the burner down when your done. The MM comes with most all the fittings you need except maybe a new gauge glass and new GG washers and the instructions that come with it are good

MilanD

@mantupsj

Someone at some time must have loved pouring concrete over steam pipes! 

That LWCO - if it's stuck, you can first attempt to dislodge the float. The chamber in there is small and float gets stuck quite easily with crud, esp if the lwco didn't get its regular blowdowns. You can flush down the lwco and see what happens. That yellow valve that's on the lwco should open and you can see if anything comes out. Then, if not, use a straightened out heavier duty wire hanger or a long screw driver, and try to gently jiggle the float free from below, up the blow down valve. You may need to remove the pipe that's there for shorter distance. And wear some protective gloves, like heavy duty welding gloves with pvc chemical gloves on top so you don't burn yourself. Just be careful not to pierce the float, so use caution for that too.

If that doesn't work, you can try removing the entire lwco, remove the pigtails and then access it from above to try to loosen up the float. Flush it out with hot water and jigle it around.

My suspicion is that lwco probably didn't get its weekly blowdowns in a looooong time, so it's probably stuck good.

Have a spare just in case none of the above works, and if works, return it. Supplyhouse.com will ship you one and take it back. You'll pay shipping for returns. Cheap insurance in my book. Get a few extra fittings where the lwco connects to the sight glass, just in case.

I don't know much about general longevity of your particular boiler, and how it reacts to so much make up water (nor how long you had the leak), so the fact that it still doesn't have a leak is good. However, I wouldn't hold my breath that it'll last for years more, so plan to replace it after this heating season, or, risk it going bad during heating season and having to do an emergency repair/replacement. 

My general suggestion is to tackle the returns asap. Given your boiler is in the pit, you may be ok with running returns either along the basement ceiling or along the floor as they will be dry returns in either case, and not need the condensate return. Less moving parts = less parts needing servicing. The reds in the basement can have their separate return, to @mattmia2 's point, if that's an issue, or you can consider disconnecting them all together.

Then, start planning for a new boiler, get quotes and ask for solutions from reputable mechanical contractors, even if you need to pay them for a couple of hours of consulting first. This is an investment for the next 20+ years, and you want to make sure everything is done to spec.

Good luck!

(Edit): one last thought: you can wire make-up from the water heater, and add an honest to goodness hot water heating system air scrubber to the line to really reduce O2. And definitely add a water meter of some sorts to the boiler supply line so that you can keep track of make up water usage. Lastly, after all the general repairs related to the boiler have been done, inspect all radiator valves and vents, and your main vents. It's good practice to replace vents when new boiler is installed.

mantupsj

Thank you @EBEBRATT-Ed & @MilanD — your advice has been much appreciated. I'll begin looking into getting these issues solved ASAP.

I've been blowing down the LWCO in the two years I've owned the building — oddly enough, the water runs perfectly clear after two or three flushes. It also does shut down the power when the water gets too low, so I wonder how that affects are stuck-float theory. I'll tickle the float and see what happens.

I hear you on the vents — I've replaced many of the radiator vents with Gortons (some of which have worked better than others). There's no main venting that I can discover, and because of those buried pipes I'm not too sure where to put one. I'll add that to the list.

Thanks again, guys, and I'll report back if there are any more twists, turns, or successes. Much obliged!

mattmia2

the main vents are on the pipes sticking above the vault with the boiler in it. That doesn't mean they are or are not adequate.

Steamhead

Instead of using a #67, I'd use a standard Hydrolevel probe-type LWCO on a #711C manifold. The manifold is here:

https://hydrolevel.com/manifold-fittings/

Then replace the 101A feeder with a Hydrolevel VXT.

You still have to blow the manifold down every week, but this setup eliminates the mechanical float and is therefore much more reliable. And the VXT will keep track of how much water is fed to the system.

Unfortunately, AFAIK that model boiler does not have tappings to install a probe-type LWCO right into the boiler section. But the manifold setup is a good alternative.

Jamie Hall

May I add a couple of things -- one is to second replacing the 67; it's easy -- but also replacing the feeder with a VXT. Not only keeps track of the water added, but you can easily adjust it for delay and amount. Nice to have.

The second is this: you are aware, I hope, that that cave is a confined space within the meaning of the act? And are treating it accordingly? Some OSHA regs don't make a whole lot of sense -- but that's one that does. Be careful and do it right.