Replacing Furnace Drain Valve
I have 4 "lines" from my oil furnace in and one of the lines has a severely corroded black iron T pipe fitting that connects to a drain valve. 2 of the other lines show no corrosion, and 1 line shows minimal corrosion. The fourth line is really corroded and drips water. Copper pipes connect to the iron t fitting. I have baseboard heat with basic copper fins.
I'd like to understand why this happend so I can properly fix the issue.
1) Why did this corrode so much? Is there some galvanic corrosion going on? See picture attached
2) If it is some sort of galvanic corrision, should I put some type of dielectric union in between the copper and iron? I've read some mixed reviews about this on the forums.
3) To replace the iron t-fitting, I am assuming I should just cut the copper pipe and replace with the iron t. Is there an optimal place to cut the pipe? See picture in link below-option1 or 2 or is there a third?
Full pictures here: http://novosandbox.zenfolio.com/p789709638
I've been a part time lurker here-but this is a great site. Thanks,