I'm replacing my old water heater and all the water lines in the house are CPVC. I'm wondering why there are unions on both the cold and hot lines near the water heater with CPVC running into and out of the unions. I thought unions were used to join different materials like copper and galvanized pipe because of the reactions between them. Is there some reason for them when all the lines are CPVC?

I use unions to make replacement easier with a valve on the side away from heater.

Shut of valves, disconnect unions and remove heater.

Put stubs from old heater into new heater. Reattach unions and turn on valves.

Good to go.

Chuck

Unless you have a special for wanting unions on your line they aren't needed. If you wish to join two lengths of CPVC a coupling is all you'll need. Good luck, Tom

Unions are commonly used to join sections of threaded pipe since the threads oppose. Don't usually see them on CPVC but it is easier to open the line.

Unions are on both hot and cold water pipes to make water heater easier to remove. With unions installed, you don't have to cut pipes when replacing water heater. Hope that explains. Milo

I agree with using unions but I think the poster is talking about dielectric unions which are more expensive and unnecessary in this case

Maybe they are heat traps, not dielectric unions?

All this is moot since the OP is piping in plastic. Unions of any kind aren't needed. And heat trap nipples will never be mistaken for unions. Regards, Tom

Hi Tom,

I agree with you that unions are not needed, but they do make replacement easier

Chuck

Nope, he said "join different materials like copper and galvanized pipe because of the reactions between them" those are dielectric but still totally unnecessary