Boiler slowly leaking

[NJC]

I have had my 20 or so year old Burnham RSM/98 boiler off since April. Now I am seeing some water on the floor. Not much - about a cup a day.

I have heard that there is cast iron in older boilers that may leak when cold. Is my only choice to turn it back on or is there a gasket or something I can replace. Or since it is leaking now, am I now required to replace something?

I have not had it on because I have been practically out of oil since April (Live in NH) and oil company wants a min of 150 gallons ($600). I couldn't shell out the cash just to have it sit in the tank all summer so I am not planning to get a delivery until about Sept/Oct.

[RBM]

It's leaking between the sections. Keeping it warm should stop the leak. You could drain it for the off season, but then you'll have to fill and purge it for the winter

[ransley]

There might be stop leak products as used in auto radiators, but plan on a new unit. Find the leak, it could be a pipe fitting rusting out. Take off the cover you should see it.

[ransley]

Dont allow any fresh water to enter now, new water is full of oxygen.

[Paul Flansburg]

RMB has the answer. The sections of a cast iron boiler have O-Rings that expand when hot/warm and contract when cool. This is why your leaking. Just for a test, start the boiler up for a few days and see if the leaking stops.

-paul

[ransley]

I have had 50 yr old section boilers that didnt leak in summer, you cant generalise a leak, it is an old boiler. He needs a pro out.

[Big_Jake]

Is it possible that the overflow (pressure relief) is leaking? They are a common failure part.

JK

[Paul Flansburg]

Not always the case. If the boiler is considered a warm start boiler then if turned off they can leak due to the O-Rings shrinking when cold. As for a cold start boiler, this is not the case.

Anyways, was looking for OP to perform the suggested test.

-paul