Copper finned heat exchanger turning green in boiler
Copper finned heat exchanger turning green in boiler
(OP)
On several low mass copper finned boilers, the heat exchanger corrodes with a green exfoliate. Is this due to over heating or what other mechanism?
Thanks
Thanks





RE: Copper finned heat exchanger turning green in boiler
RE: Copper finned heat exchanger turning green in boiler
Next time you see a copper roof of any age at all, note that it is green.
RE: Copper finned heat exchanger turning green in boiler
With most low mass copper finned tube boilers and water heaters, the copper finned tubes do not corrode to an exfoliated green flaky 'stuff.' Of course all copper like aluminum, reacts on the surface with atmospheric oxygen to form an oxide, which is technically corrosion, but this is not what I'm concerned with.
One look at the corroded tubes I'm talking about and you would know instantly that there was a serious problem with the boiler. The question is: Has low stack temperature / condensation caused this condition, or has low flow / over heated tubes caused the problem?
And thanks for the response to my question. I love this forum. I need to visit it every day.
RE: Copper finned heat exchanger turning green in boiler
RE: Copper finned heat exchanger turning green in boiler
RE: Copper finned heat exchanger turning green in boiler
The top pic is what a copper finned tube from a boiler heat exchanger should look like.
The middle pic shows what a typical 'green' tube looks like,
The bottom is interesting and I see it a lot. The heat exchanger is a 2 pass. Water flows to the right in the first 6 tubes, turns around and flows to the left and out of the boiler. The metal temp in the first 6 tubes will be lower than the back 6 tubes.
Steve
RE: Copper finned heat exchanger turning green in boiler
Typically condensing boiler heat exchanger is therefore of stainless steel construction.
I hope the reason why the first pass is green(third photo) is clear now
RE: Copper finned heat exchanger turning green in boiler
As to the return water temperature... it varies but is usually less than 140°F (60°C) so there is likely some condensation taking place.
RE: Copper finned heat exchanger turning green in boiler
The quality of natural gas also can be a cause for tube corrosion for eg high sulphur content or presence of H2S
RE: Copper finned heat exchanger turning green in boiler
My question is, 'would flue gas condensation' accelerate such corrosion.
Steve