exhaust from condensing boiler

Xmytruck

Silly question but I am assuming white steam (cloud) exhaust from the flue is normal during the winter? If so is too much steam a bad or good thing? i notices a house in my neighborhood with pvc flue and I do not see steam from that exhaust.
Thx

bmwpowere36m3

It depends on the exhaust temp and the fire rate of the boiler… so high exhaust temps and fire rates will result in lots of steam. You could infer that the less steam visible, the "better" the boiler is operating (lower exhaust temps and fire rates).

For example: if it's 40* out, my boiler flue temp might be ~110* and be on low-fire… I can see steam clearly (not like a locomotive, but noticeable).

Xmytruck

Thank you.

Mark Eatherton

What you are seeing is energy and money being wasted. In a high efficiency appliance, there is little to no energy left in the flue gas stream. In some cases (steam) there may be a hole in the heat exchanger at or above the standing water line, and when the boiler is steaming, it is losing a LOT of paid for energy up the chimney.

That kind of leak rarely shows as water puddling below the appliance, and require the vessel to be "flooded" in order to show the fault.

As with any hydronic question, the only correct answer is "It depends..."...

ME