Combo wood/ oil boiler issue

[Bing187]

Hi all,
Had an issue recently with boiler at girlfriends house. It's a 25 year old Burnam oil/ wood / coal combo boiler.
Woke up one morning to a lot of gurgling in baseboards upstairs. Figured system needed to be bled, though it was strange that boiler had been serviced two weeks prior, wondered if it was connected... Went to the basement and there was water pouring out of the coal door at bottom of unit.
She called the company that does service, I had to leave for work. Guy came and looked at it, scratched his head and said, "I don't really know anything about these units, but I'm sure I can figure it out..." He proceeds to try to shut off water to unit, water still coming out around the coal door, so he figures the shutoff valve doesn't work In retrospect, it was water sitting in the coal bin, not under pressure, still leaking around gasket, not leaking because there was still water pouring out... but I digress...

He then shuts off water to house at meter, breaks shutoff. Tells GF that she needs to get plumber to replace shutoff and he'll come back to fix boiler.

I call my plumber, he comes and replaces shutoff. Purges boiler, fills system back up, turns boiler back on. He did mention that of the three "High vents" on piping, two aren't working, need replacing. Has no idea where water in coal bin is coming from, but if I find out, he'll fix whatever needs fixed. Of course at this point I'm thinking something has rusted out, or boiler is cracked.....

I open door of coal bin, which is now not dripping. About an inch of water remains in box. Shop vac it out. After a while, box dries out completely, and hasn't dripped or had any water in it since, bone dry.
This was about a month ago, and heat and boiler has been fine since. No gurgling, no water leaking, working perfectly.....

Where the heck did the water come from? and what do I need to do for service on this thing in general? She's never used the wood portion of the boiler. Her ex did years ago, but not for 20+ years. I'm a wood stove guy, burn a lot of wood, but really don't know a thing about combo boilers.

Thanks in advance for anyone that knows what's up... I'm in the process of sniffing out a tech that's familiar with these and can take over the service aspect, but would like some kind of clue to start with....

 

[lknchoppers]

Without knowing the layout of the water jacket of the boiler it's hard to tell. Can you dig up any diagrams of how this boiler is engineered?

 

[Franny K]

There generally is a device that automatically bleeds air out. Probably the high vent things mentioned. They can misbehave intermittently. Could that be the source of the water?

 

[NSMaple1]

Hard to see from here where the water could have came from.

I don't know anything much about your Burnham (pics might help) - but, some old school wood boilers used to direct the outflow from their blow off valves, thru a pipe thru a hole in the side of the firebox, right into the fire. Anything like that going on?

 

[Bing187]

The high vents aren't near the firebox for the coal, and they're sort of on their own at top of piping, so if it were leaking there, it would just run onto the floor.

I don't have a diagram of the configuration of the water jacket or piping; that would probably be my next move. I did take pictures of the tag with serial numbers, and a few of the outside of the boiler, so it wouldn't even require a trip downstairs....

NS Maple, I'm wondering if you're on the right track. I wondered if there could be a blow off or relief valve inside that dumps into firebox. Can't see one, but I didn't exactly stick my head in there. That's about the only thing that would make sense to me, since it hasn't leaked a drop of water since....

 

[NSMaple1]

The one on my fathers is pretty obvious. There is a copper pipe running from the blow off valve on the top of the boiler, over to & down the outside of the boiler towards the front, until it turns & disappears into the firebox.

No idea about coal bins, have never even seen one.

 

[Franny K]

That makes sense, if it overheats cool the fire. Gas or oil the overflow seems to stop a foot from the floor, put a pail. Not unusual to get some liquid after a service, never been that much. To have two professionals come and not jiggle the over pressure thing in this instance??????