Time to replace my old boiler?

MyAncientBoiler

I bought my 3BR house in the 1990s and with it came an ancient converted coal boiler that heats the house with steam through single-pipe radiators. Until recently, it has worked very well. It keeps the house warm and doesn't seem to cost an arm and a leg. It is long in the tooth, however, and I'm sure there are many things that are questionable (like I have no doubt there is asbestos).

As I was taught when I first bought the house, I periodically check the water level on a glass tube along the side, and if it runs low, I add some up to about halfway where there's an embossed mark on the side of the boiler. 4-6 weeks ago, as I was doing laundry, I added some, then went upstairs. After about an hour I went back down to switch laundry to the dryer and noticed water all over the floor.

I called my plumber (an older guy who is semi-retired), and he said I probably just overfilled and I only really needed an inch or so showing on the tube, so I drained water off to lower it on the tube and that seemed to solve the problem. And since it's no longer heating season and my work was very busy, I figured I'd have him come out later to look at it and see if there was a crack somewhere.

Since that happened, I've been checking the basement periodically to see if there's been any water on the floor and there hasn't, but I noticed the water level on the tube going up a little higher even though both valves to add water were closed. Maybe condensation from the radiators flowing back to the boiler? I don't know, but I would blow off a little bit of water to keep the level from getting too high.

Yesterday, I noticed that it seemed to be a little high again, and this time when I went to open the valve on the side of the boiler, the whole thing, downpipe and all, snapped off in my hand.



I tried screwing it back in, but it seems like the piece at the bottom where it screws in basically just crumbled into nothing. The water came out of the boiler and fortunately, I was fast enough with buckets that it wasn't too much of a mess.

I turned off the heat at my thermostat, then called my plumber, and he talked me through shutting off the gas to the boiler. Since it's not a huge emergency since I don't need heat, he's coming by tomorrow to take a look.

I'm assuming this will mean it's probably time to replace, but any chance at all this might be able to be fixed?

This is ancient, for sure... last time I had someone other than my regular guy look at it, he was amazed and acted like it belonged in a museum or something. Here is a picture of the product nameplate on the front:



From what I could tell, this model was made in the 1940s through the 50s, so whoever bought it got their money's worth.

Thanks for any insight.

JUGHNE

That LWCO control valve can probably have the bottom plate replaced.
However simply because of the age of that critical safety component it should be replaced. Manf. says to change it after 10-15 years.

IIWM, I would remove the control. You may have to remove the sight glass valves which most likely need cleaning anyway.

Then plug the boiler openings where the sight glass was connected.

Then make sure that the boiler drain valve functions...the hose bib. You will need this to drain out the water for the "boiler flooding" test as described below.
With the boiler drain open fill the boiler to see if it will drain.
You can try back flushing with a double female hose connected to your washer supply. This might blow the junk in the drain back into the boiler so it will drain.
If no success there, you can unscrew the hose drain and install a 3/4" pipe with ball valve and hose adaptor.

Then, with the ability to drain down the boiler later, over fill the boiler to where you feel the cold water rising up the steam riser on the boiler.

Leave it sit to see if any water then leaks out, if so plan on a new boiler for sure.

A crack or hole in the boiler cannot be repaired.

It is pretty hard to over fill a boiler that makes it leak onto the floor. Water would come out of the air vents first. All other piping including the boiler should be water tight.

The water you saw could have been from the blow down connection which may have started leaking before it broke off.

Price the replacement LWCO, that may make you then consider a new boiler.

Figure the EDR of you connected radiators and use it for sizing a new boiler.
Yours may well be over sized.

Come back with and for more info.

109A_5

If that is the only problem, I would say No it is not time to replace your boiler. To me that black cast iron assembly looks like a McDonnell & Miller #67 Low Water Cut Off. At the bottom of that LWCO there is a plate held on by 4 screws called a Dirt Pocket that your valve was attached to. It can be replaced, sometimes the screws come out with some difficulty. The screws may be straight slotted or Hex Key head type in my experience. Some LWCOs have a whole Blow Down valve assembly attached with the 4 screws. Both the Dirt Pocket and the whole Blow Down valve assembly are available on eBay, maybe other places too. Don't forget the gasket if the new part does not come with it. A handy home owner should be able to make the repair if they have the right tools (don't forget to clean off the old gasket), it should be no problem for a seasoned Plumber. I keep a spare valve assembly since they start leaking every 10-20 years. I was thinking of changing over to the Dirt Pocket version like yours since a common ball valve like yours is cheaper to change if it leaks. On eBay check out these as a reference;

315450 replacement Dirt Pocket Cap for McDonnell Miller 309510 (47-171, RM-889)
https://www.ebay.com/itm/265294564087

McDonnell & Miller 14b blow down valve L38-713 (47/ 67/ 70B replacement valve
https://www.ebay.com/itm/313830459856

"but I noticed the water level on the tube going up a little higher even though both valves to add water were closed" Your fill valves may be leaking.

"After about an hour I went back down to switch laundry to the dryer and noticed water all over the floor. "
This may be an issue, a boiler should hold water even if it is full to the top, just don't run it that way !!!

The LWCO should be Blown Down on a regular basis to keep the LWCO float from getting stuck. When fresh water is added run the boiler to get the oxygen out of the water.

MyAncientBoiler

Thank you both very much for the info. I'm hoping to be able to get away with just replacing that dirt pocket cap. It sure seems like maybe that initial leak could have come from that part starting to fail, except that I always keep a bucket under there so it doesn't seem like water should have been on the floor. I'll see what my plumber says when he's able to look at it. Thanks again.

pedmec

yes you can replace the blowdown plate provided you can get the screws out

MyAncientBoiler

Update: He replaced that blowdown plate. Last one in stock at his local plumbing supply. No real answer on the leak situation (seems like it could have been a leak from that plate the more I think about it), but he just said to keep running this as-is if I'm happy with it. Thanks to everyone who answered.

ethicalpaul

My opinion: don't trust that plumber with your steam system

mattmia2

Someone should flood it to make sure it isn't leaking above the water line, but you would be adding water frequently if it were leaking.

Hap_Hazzard

Consider replacing the LWCO with a probe type unit. They don't require blowdowns. You can probably put it where the lower trycock is installed. (That's the thing to the right of the lower glass gauge fitting.) You don't need trycocks if you have a glass gauge.

I don't think you should think about replacing the boiler either, especially if it's working well and there's asbestos involved. The rule of thumb for asbestos is to leave it alone unless you absolutely have to remove it, and then have a licensed professional deal with it. I'm a big advocate of DIY, but asbestos is the exception. Mesothelioma is a horrible way to die.

Hap_Hazzard

MyAncientBoiler said:

It sure seems like maybe that initial leak could have come from that part starting to fail, except that I always keep a bucket under there so it doesn't seem like water should have been on the floor.

Water escaping from a crack in a pipe under pressure could go anywhere and everywhere.

Chris_L

Too late now, but I don't think you needed to replace the plate at the bottom of the LWCO. Assuming, that is, it was the nipple that broke as it appears in the photo. You just needed to clean out the threads in the plate.

I've had this same failure. A few weeks ago, when I was scraping out the inside of the LWCO, I decided to remove the replacement steel nipple to inspect it. Here is a photo:

Fortunately, I caught this one before it broke off. Not sure why these nipples have such a short life, but I'd recommend a brass nipple for adding the ball valve to the LWCO.

(I used a brass male x female ball valve, and now I've started getting a blast of blue in the initial blowdown water. I am hoping that doesn't mean this connection will have a short life, too.)

109A_5

@Chris_L, To me it looks like the nipple above the valve has a Hex on it and all the expected threads are still there (just junk in the threads), so I think it is brass so the Dirt Pocket cap plate rotted away. Also @MyAncientBoiler you should verify that your fill valves are not leaking. Constantly adding fresh water to the boiler will kill the boiler !!! With Asbestos as an issue I would make that boiler last as long as possible.

MyAncientBoiler

109A_5 said:

Also @MyAncientBoiler you should verify that your fill valves are not leaking. Constantly adding fresh water to the boiler will kill the boiler !!!

In the two days the cap plate was off, no water dripped out beyond the initial water. Pretty sure that means they're okay, right? Or else there would have been constant dripping those two days.

EBEBRATT-Ed

@ChrisJ Black

Black

nipples don't seem to do well on a boiler unless they have flow going through them. They seem to suffer under lukewarm temps.

As far as I am concerned Low water cutoff fittings, pressure gauges, pressure controls should all be brass

ChrisJ

EBEBRATT-Ed said:

@ChrisJ Black Black nipples don't seem to do well on a boiler unless they have flow going through them. They seem to suffer under lukewarm temps. As far as I am concerned Low water cutoff fittings, pressure gauges, pressure controls should all be brass

I didn't comment but you're probably right.

Chris_L

ChrisJ said:

EBEBRATT-Ed said:

@ChrisJ Black

Black

nipples don't seem to do well on a boiler unless they have flow going through them. They seem to suffer under lukewarm temps.

As far as I am concerned Low water cutoff fittings, pressure gauges, pressure controls should all be brass

I didn't comment but you're probably right.




That was me.

Thanks @EBEBRATT-Ed. Better to learn that here than when boiling hot water is rushing out of your boiler after you do a blowdown to test your LWCO and the valve falls off in your hand.

109A_5

MyAncientBoiler said:

In the two days the cap plate was off, no water dripped out beyond the initial water. Pretty sure that means they're okay, right? Or else there would have been constant dripping those two days.

@MyAncientBoiler As you did, you would have to ask the question where is the extra water coming from. No dripping when the Dirt Pocket cap was off seems to eliminate the fill valves. I may have the timeline wrong but it appeared the water rising was over the course of a few days before the valve fell off. To me condensate should return almost as fast as water going down the drain of a sink. It warms up my wet return rather fast. In my opinion if condensate takes days to return something is very restricted, wet return, dry return, bottom of the boiler. Or the fill valves intermittently leak. Where else could the water be coming from? I would monitor the situation, any long term continuous rise in the off season to me is a leaky fill valve. If condensate is being trapped at the far end of the system it may cause issues in the future.
A condensate return water flow video https://youtu.be/97jhq7fSTuU

mattmia2

Is that @ethicalpaul 's video?

109A_5

Yes @mattmia2 I believe you are correct. I think it is an excellent visual aid to part of what I was trying to explain to @MyAncientBoiler. Thanks to Paul we all can now see what was once rarely seen.

pecmsg

EBEBRATT-Ed said:

@ChrisJ Black

Black

nipples don't seem to do well on a boiler unless they have flow going through them. They seem to suffer under lukewarm temps.

As far as I am concerned Low water cutoff fittings, pressure gauges, pressure controls should all be brass

Actually, some stainless is cheaper that brass today.

ChrisJ

pecmsg said:

EBEBRATT-Ed said:

@ChrisJ Black

Black

nipples don't seem to do well on a boiler unless they have flow going through them. They seem to suffer under lukewarm temps.

As far as I am concerned Low water cutoff fittings, pressure gauges, pressure controls should all be brass

Actually, some stainless is cheaper that brass today.

The only thing I'd warn about stainless is where brass is soft and conforms well, stainless steel threads will not be as easy to seal especially if there's imperfections.

ethicalpaul

The condensation does return pretty quickly...but it does take a few minutes after the end of boiling for it to all come back (well most all)