dielectric Unions

Deano

Are dielectric needed or required on hot water heating systems?

bob_46

No

Snowmelt

NO, but you have to having a grounding strap from what I hear, thats what the dio do from my understanding

SWEI

Not needed in a closed system (and adding one to an open system won't help anyway.)

hot_rod

Here is what dielectric unions often do. This was probably a domestic water system.

unclejohn

Dielectric unions all only needed to help find the leaks in a system. The leaks are at the dielectric unions.

jumper

Depends. On conditions and what sort of dielectric is used. Look at the opposite point of view. Those fancy copper shower bath fixtures which include overflow and drain.Works of beauty.But an evil plumber will substitute one little ferrous piece somewhere.To create work for his grandson's generation? Drain piping is dry 99% of the time. But that little ferrous piece will plug up the copper over the decades.

So how do we join dissimilar metals? Is that pipe in HotRod's picture galvanized on inside? How hot was the water? And so on.
Maybe the crud is in spite of dielectric? Depends.

SWEI

jumper said:

So how do we join dissimilar metals?

For potable water? A foot or two of PEX or Aquatherm works nicely. We used to use a threaded Schedule 80 PVC nipple on wells (cold water), but it's not code approved.

hot_rod

jumper said:

Depends. On conditions and what sort of dielectric is used. Look at the opposite point of view. Those fancy copper shower bath fixtures which include overflow and drain.Works of beauty.But an evil plumber will substitute one little ferrous piece somewhere.To create work for his grandson's generation? Drain piping is dry 99% of the time. But that little ferrous piece will plug up the copper over the decades.

So how do we join dissimilar metals? Is that pipe in HotRod's picture galvanized on inside? How hot was the water? And so on.
Maybe the crud is in spite of dielectric? Depends.

On a closed loop piping system there is no need to have any separation between metals. It becomes an O2 free system after a few days and no corrosion is possible without O2.

Unless of course you connect non-barrier tubing into the system

A brass nipple is a good isolation between copper and steel, like the water heater port.