Condensation in Boiler Flue

Jim Walters

I'm getting quite a bit of condensation it the double-wall boiler flue of my in-floor heating system. Am I running the boiler wrong at 16psi and 120 degrees F?

kf_2

condensation

16 PSI is probably not the problem, but depending on the type of boiler the 120 F. temp certainly could be. If it is a cast iron or steel boiler I would be more concerned with the condensation you are, no doubt, forming on the fire side of your heat exchanger.

What kind of boiler is it?


kf

Unknown

Any idea what your

return water temperature is. If it is very low and I assume it is if you are running at 120 degrees then you are probably also condensing in the boiler.

You need to run the boiler at a higher temperature and then temper water to the system, then in turn the return water will still be low but you can have a bypass connected to the system to take care of that.

Some of the pro's here on the Wall will give you a possible set up for what to do. Please give a little more info about your boiler and system to help them help you.

hr

You need

to address that soon. Those temperatures will quickly eat away the aluminum liner in you B-vent system.

Conventional (non condensing) boilers need to operate above the fuel dew point. Somewhere in the 130°F range, foe natural and LP gas..

Damage to the heat exchanger will also occur, the flue pipe seems to take the brunt of condensing temperatures first.

You need a method to run the boiler temperature up, mix down for you system requirements. AND provide a means to watch and respond to low return temperatures to the boiler.

Sounds complicated, but doesn't have to be

Plenty of electronic and mechanical means to get there

hot rod

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