Thread: Cat IV condensate

Is there any problem with using a copper drain line for a Cat IV boiler? There was some corrosion at the fitting between the CPVC and the copper.

The plumber told them it was okay, but I thought it would be better to run it all in CPVC. I looked in the Safet T Vent instructions and Weil McClain instructions, and didn't find any specific mention of type of pipe to be used.

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AFAIK, that connection needs to be made with a compression fitting listed for CPVC.

Silicone or rubber tubing with a loop trap. That acidic condensate will eat up that copper just as you see. I've seen condensate drips eat a crater in a concrete floor.

The copper would probably be fine with a proper connector between the plastic and copper connection. The reducing slip coupling over the plastic does not provide proper seal. I didn't notice but if you're going to use copper for that, at least use type L.

Like Bob already said, the condensate is acidic. I know a local contractor who had to repair a ceiling where the copper condensate drain rusted through and damaged the ceiling.

I think I may have mentioned this in another thread recently. A bunch of us HI had a CE meeting one morning a while ago with a local plumbing shop. They are seeing more and more eaten away copper traps in Condo floor drains that 90+ furnaces are run into. They've fabricated their own filter that they sell to customers.
1' section of 2" PVC pipe with a threaded end cap, pipe is filled with gravel and something else (don't remember what) in order to neutralize the acidity before it continues into the drain. Not commenting on the validity of it, just saying that that is what one plumbing outfit is doing here.

Noritz Tankless water heaters has a model that uses PVC venting and it has a built in acid neutralizer as Mr. Keller described that a plumbing shop is fabricating. It just has limestone in it to neutralize the acetic effect of the condensate.

Lots of areas will not allow CPVC used as a drain. So what they do allow is the condensate drain to be CPVC or PVC to an acid neutralizer, then it has to be copper or galvanized pipe from there on.