Can I use teflon tape instead of a dielectric union?

[bjrubble]

I have a friend who says that a thick wrapping of teflon tape around the threads is perfectly adequate for joining copper to galvanized steel. I've also heard various people claim that dielectric unions are practically useless anyway, and that a segment of brass is the most effective measure. On the other hand, I've also heard that brass mated to galvanized steel also needs a dielectric union.

I'm planning to replace everything in the house with copper, except the pipes in the bathroom walls and the line from the street. I figure I'll get to the bathroom eventually, but I'd rather not dig up my front yard. What are my best options?

Also, all my wiring is new, and as far as I can tell none of it is grounded to the existing pipes. Do I need to worry about grounding the new stuff?

 

[Cass]

Are you talking about a water heater or something else?

For the water heater I like dialetric nipples or a brass nipple.

If you are transitioning a peice of water pipe I would use a brass nipple with teflon tape on the threads.

 

[Sponsor]

 

[hj]

tape

Dielectric unions are COMPLETELY worthless. Teflon tape is intended to "disappear" when the joint is made and just fill any voids in the thread. The actual threads are in metal to metal contact so electrolysis can still occur. Brass, being between steel and copper on the Nobility scale acts as a transition, which is why we can install brass valves on copper OR steel lines without dielectric provision.

 

[Jimbo]

Over-wrapping could lead to a leak, but almost surely would not completely isolate the nipple electrically.

 

[Fubar411]

I have a friend who says that a thick wrapping of teflon tape around the threads is perfectly adequate for joining copper to galvanized steel. I've also heard various people claim that dielectric unions are practically useless anyway, and that a segment of brass is the most effective measure. On the other hand, I've also heard that brass mated to galvanized steel also needs a dielectric union.

I'm planning to replace everything in the house with copper, except the pipes in the bathroom walls and the line from the street. I figure I'll get to the bathroom eventually, but I'd rather not dig up my front yard. What are my best options?

Also, all my wiring is new, and as far as I can tell none of it is grounded to the existing pipes. Do I need to worry about grounding the new stuff?

If you see wires coming from electrical boxes, that means they're using an old method of achieving ground. It is no longer code to do that. If you have wires that are are bonding the pipes to ground, those need to stay.

 

[Mike Swearingen]

bjrubble,
Have you seriously looked into PEX instead of copper?
Mike

 

[bjrubble]

Thanks

Thanks for all the prompt replies.

I have copper in a bunch of the existing lines (including to and from the water heater), and I already bought a bunch of the materials, so I'm pretty committed to copper. I'm replacing the main mass of pipes, from the main line and into all the fixtures (there aren't many, it's a pretty small house).

It sounds like brass nipples are the best way to go. I'm guessing that this would maintain a conductive path, eliminating the need to worry about grounding -- is that accurate?

 

[frankthetank]

I replaced this Rheem hot water heater the other day (It was 17 years old and i thought i was pushing it). There was no dielectric unions of any sort connecting to the tank and as you can see by this picture, the cold was pretty rusty (not leaking or anything) and the hot looks brand new. A little sandpaper and some new teflon and it'll probably go another 17 years



I say they are worthless. I used copper directly on my pressure tank because i figure the it'll last longer then the bladder will!

 

[Geniescience]

.... It sounds like brass nipples are the best way to go. I'm guessing that this would maintain a conductive path, eliminating the need to worry about grounding -- is that accurate?

yes, conductive path maintained. over and out.

david

 

[Kordts]

In my area, dielectric unions are pretty much worthless. Brass to galvanised lasts a little longer, but the best way is to use stainless as a dielectric connection.

 

[Dubldare]

I replaced this Rheem hot water heater the other day (It was 17 years old and i thought i was pushing it). There was no dielectric unions of any sort connecting to the tank and as you can see by this picture, the cold was pretty rusty (not leaking or anything) and the hot looks brand new. A little sandpaper and some new teflon and it'll probably go another 17 years




I say they are worthless. I used copper directly on my pressure tank because i figure the it'll last longer then the bladder will!

You're joking right? Those are dielectric nipples with heat-traps on that old rheem. Probably what helped it last this long.