Dielectric Unions

Dielectric unions

PostBy: gregsmit On: Sun Aug 03, 2008 8:09 am

I'm using a combination of black iron and copper to pipe out my new KA6.

Are dielectric unions required between the iron & copper? As best as I can determine from a search on the Web they are not needed on boiler piping but I'd like to understand why not.

Thank you,

-Greg Smith
Stove/Furnace Make: Keystoker
Stove/Furnace Model: KA6 direct vent

Re: Dielectric unions

PostBy: Freddy On: Sun Aug 03, 2008 8:28 am

You can directly go from copper to iron. If there's an electrolisis problem you won't know it for 75 years or so. I think it's not an issue because you're not changing the water every day.
Stoker Coal Boiler: Axeman Anderson 130 (pea)
Hot Air Coal Stoker Stove: Reading piece o' junk in the barn (rice)
Coal Size/Type: Pea size, Superior, deep mined

Re: Dielectric unions

PostBy: traderfjp On: Sun Aug 03, 2008 11:54 pm

I asked this question too when I was doing my coil and a few people in the trade told me what Freddy already said.
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing 3

Re: Dielectric unions

PostBy: e.alleg On: Sun Aug 10, 2008 10:17 pm

The trouble is when the water cools down the copper will contract faster than the iron, and similarly when things heat up the iron heats up slower than the copper. In a threaded joint copper-to-iron you might get a leak, it is inevitable. It will seal itself up with rust within a couple months. The dielectric union will help out in this case, but they are expensive and probably not necessary.
Stove/Furnace Make: EFM
Stove/Furnace Model: 520