pressure testing boiler and tankless coil problems

[Carl Webber]

I recently picked up a wood boiler with a domestic hot water coil in it. Before i go to all the work of putting this thing in my basement i wanted to make sure it was all set. I decided i was going to pressure test it with air, and then flush it with water to make sure its clean. I plugged all the holes in the boiler and i tried to apply pressure to the boiler. Every time i give a burst of air, all the air comes back out the connections for the DHW coil. I can't get the boiler to build up pressure without plugging the lines coming out of the DHW coil. From what i know, this means that the DHW coil is bad and rotted through internally somewhere. Am i correct? I do not plan to use the DHW coil. I plan on installing a superstor and running a zone for it. Can i just plug the holes in the DHW coil and use the boiler as is, or is my boiler completely useless with the coil leaking? The connections to the DHW coil are 3/4" threaded connections so my plan was to just put plugs in them and use the boiler like it is, but i'm not sure if that will work. Can anyone shed some light on the subject? Thanks in advance.

 

[maple1]

What kind of boiler?

My old tankless coil unit had gaskets around the coils. Those would leak after a few years & require replacing. If I was certain I would not be needing the coils, I would be tempted to take them out & have the holes plated & welded over. But if you don't have gaskets to worry about, I don't think it would hurt to plug & run like that - unless the corrosion was real bad & almost worked out to the connections. With the boiler sealed up & running the way closed pressurized boilers are run, it shouldn't corrode any more - chances are it corroded from the inside from the oxygen rich fresh DHW going thru it.

 

[Carl Webber]

The boiler is a Tarm OT-50. The coil in these things is huge. I had someone help me remove it. It appears like when the boiler was disconnected the guy tried to drain all the water out but couldn't because the coil is vertical and not horizontal. It appears to me like the little bit of water he couldn't get out collected in the bottom of the coil and froze. At the bottom of the coil there are 2 or 3 spots where the copper tube has burst. I could be all wrong about this though. It is entirely possibly that the coil just corroded through as the boiler was manufactured in 1979. The cover for the coil appears to be good to me. I just wanted to make sure i could put plugs in the cover and not have to worry about blowing anything up.

 

[BoilerMan]

I would remove the coil for the scrap copper. Just cut it off behind the plate that bolts into the boiler, and ust two 3/4 pipe plugs in the plate and reinstall with new gasket, or high temp RTV if the mating surface is badly pitted.

TS

 

[Carl Webber]

Thanks for the help. I think i'll just plug the holes and get a superstor as a new coil for one of these is $500 and the superstor will make the boiler more efficient.