I currently have galvanized plumbing throughout the majority of my home. I had the valve for my shower replaced with copper (due to a problem) and am having the hot and cold vertical pipes replaced with copper today while the wall is open. I have a few questions regarding copper and galvanized pipes:
1. If the shower valve is copper and it connects to galvanized pipes (such as the pipe from the valve to the shower head) could this damage the copper?
2. If the pipe that goes to the shower head is not rusted is it necessary to replace it with copper? (I am changing out the other pipes while the wall is open – I don’t want to have to open this wall again when I replace the balance of the house with copper).
3. If the plumber uses a filtration system (a nipple) between the copper and galvanized pipes, will there be a build up of rust between the two pipes where the nipple is located?
4. If I can’t replace all of the galvanized pipes now, does it make sense to do change any of them?
1. If copper is attached to the galvanized piping it is the galvanized piping that will corrode. 2. Change the riser pipe to the shower head now while the wall is open. 3. Definitely have the plumber install a brass nipple in between the copper and galvanized piping. This will help prevent deterioation of the galvanized piping. I have had a similar situation in use for 5 years without any problems. 4. I would definitely change the pipes in the wall while it is open.
Wherever you connect copper to galvanized, you need a dielectric union to prevent galvanic corrosion.
If you cannot change all of the galvanized now, try changing the last 10 feet of galvanized, this is the section that will have the highest corrosion pluggage. Make sure you put dielectric unions at every junction of copper and galvanized.