Do I have a leak on my heat exchanger?

[Tom walsh]

i have a gb-142 that I maintain, or try to because no one around me will touch it. Not even the installer, but that’s another story.
Recently I noticed a wet spot on the floor. Found water dripping from outside the case way up in the back where it mounts to the wall. Someone told me the exchanger was leaking. If that was true wouldn’t it be in the case and dripping into my condensate collector? I’m talking about the aluminum case that surrounds the heat fins.

Started when it got really cold. Only drips when the boiler shuts down as far as I can see. Pressure is still up.
Figure maybe exhaust condensation is freezing in the flue pipe and flowing back down and getting hung up by something and leaking somewhere back there. Does that sound slightly logical?

 

[Dana]

You're right that the leak water would likely end up in the condensate collector if the HX were leaking. Turn off the isolating valve ahead of the system's auto-fill valve, see if the system loses pressure over a few days. If it doesn't lose pressure, it's not leaking.

Another possible (even likely) scenario that shows up more often during very-cold weather is condensation of boiler-room air on the exterior of the combustion air intake ducting.

Test the acidity of the drip water (or taste it, for a quick check). Natural gas and propane exhaust is somewhat acid, and distinctly tangy, and would be an indication that it's exhaust condensate, not leak water, and not room-air water condensing on the intake duct.

 

[Sponsor]

 

[Tom walsh]

You're right that the leak water would likely end up in the condensate collector if the HX were leaking. Turn off the isolating valve ahead of the system's auto-fill valve, see if the system loses pressure over a few days. If it doesn't lose pressure, it's not leaking.

Another possible (even likely) scenario that shows up more often during very-cold weather is condensation of boiler-room air on the exterior of the combustion air intake ducting.

Test the acidity of the drip water (or taste it, for a quick check). Natural gas and propane exhaust is somewhat acid, and distinctly tangy, and would be an indication that it's exhaust condensate, not leak water, and not room-air water condensing on the intake duct.

Thanks Dana. I will have to check that out.