Why Copper Condensate line is incorrect

Last fall I called out a copper condensate line from a horizontal furnace in an attic as being incorrect. The home owner had a HVAC Tech inspect it and he said I was wrong and there was nothing wrong with using copper. They wanted me to pay for the service call which I did not. (longer story)
My client purchased the home and called me last week to tell me they saw stains on their ceiling.
After they called a roofer who told them to call an HVAC Tech, they shared with me these pictures of parts of the copper line. You can see the holes that were caused by the condensate.
Note the install is 6 years old.


Good catch, thanks for the share, Joe. :slight_smile:


Great find! Never saw a copper condensate line, much less in the attic. Good pictures.


Wow Joe, so the corrosive condensate from the HE furnace was the cause, looks like there may have been a possible chaffing issue as well. I never would have thought of the copper being such a problem.

Thanks for sharing. :+1:


The HVAC Tech told the home owner if the line has heat tape on it, it must be copper. I called BS.
Self Regulating heat cable only puts out 3 watts which is not enough to melt PVC.


I was about to say, copper freezes faster than PVC.
Regardless of material, they should be insulated.

They also used Type M copper, thus the short life.

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Copper is used in many commercial HVAC applications, but not if the unit is high efficiency.
Many new high efficiency furnaces are being installed in old homes with cast iron floor drains. The acidic condensate will also damage/destroy the cast iron until the condensation is diluted further downstream.

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Not many people realize this David.