Cracked Steam Boiler?

JachL

We recently had our plumber in to service our Weil McClean steam boiler. Just before he was getting ready to leave he noticed a small amount of water on the floor near the boiler. He said, "I'm sorry to tell you this, but your boiler is cracked and you're going to need a new one." The boiler was not leaking any water before he came. After he left, the boiler continued not to leak any water. When I called him several weeks later to ask about this he said the boiler is only going to leak when he fills it all the way up to the top to test it and that the water level is low enough so that its not leaking. So my question is, if the boiler only leaks when its filled up to the top, and its not normally filled up to the top, do I really need a new boiler? It is continuing to run fine and not leak. Thanks very much for any advice.

nicholas bonham-carter

Is the system losing water, and needing to be refilled?
If there is a leak higher up in the sections, then steam will exit the boiler into and up the flue, and you won't see a puddle on the floor.
As more and more fresh water is introduced into the boiler, the rusting will accelerate. Have the plumber do the overfill test again to determine the size of the leak, to see if you can get through the winter.
When replacing the boiler, do not choose another based solely on the rating plate of the old one. The radiators must be measured, and the EDR calculated to size the new one.
Post a picture of the present boiler piping, so we can advise on the repiping.--NBC

Jamie Hall

NBC is right, and the key question -- which you can answer fairly easily -- is do you need to add too much water to the boiler to keep it at the right level? The way to do this depends on how water is added. Some boilers are fitted with automatic water feeders, and these come in two varieties: with and without a water meter. If it has a water meter, it's really easy -- anything much over a gallon a week is too much, and it's leaking. If it doesn't have a meter, then you will need to turn it off and close the valve to it. Then keep an eye -- at least daily -- on the water level in the sight glass. If it goes down fairly quickly, so that you need to turn the feeder back on in less than a week, then you probably do have a problem. The same thought applies to a fully manual feed: if you need to add water fairly frequently to keep the water level where it belongs...

Otherwise, you don't have a problem. And in this instance, I would be exceptionally wary for one simple reason: being gently (?) paranoid, I'd be inclined to wonder how that water -- near, but not at -- the boiler got there. Leaks in the upper part of a boiler usually either go into the firebox, where you won't see them, or drip down the side of the boiler and appear -- if at all -- right under it. Just sayin'.

Fred

You can also do what he says he did??? If you want. shut the boiler down for a couple hours to cool a bit. Fill it up until you can feel the cool water up to the riser pipe(s) and let it set for an hour or so. If you see water leaking sooner, you'll have your answer. If not, and it doesn't leak in an hour, it likely is not leaking and maybe, just maybe the guy is trying to sell you a new boiler. When you're done, drain the water down to the normal level in the sight glass and fire the boiler up again. What the guys above have said is the easiest way to tell if something is leaking, even though that might be anywhere on the system/piping and not just the boiler.
How old is the boiler?

JachL

Thank you everyone for all of the good advice. I'm not sure how old the boiler is and it does have an automatic water feeder without a meter on it, so I'm not sure how much water is being added. I'm going to explore all of these suggestions- thank you.

nicholas bonham-carter

You could turn off the water supply to the feeder, and see if the boiler runs out of water in a short period of time.--NBC

David Sutton_6

while your boiler is making steam , go outside and see if there is white smoke coming out, if so you either have a high crack or electing a new pope .