Alternative to dielectric union

I've heard that a brass nipple can be used to join copper to galvanized pipe instead of a dielectric union. Is this true? How long does the nipple need to be? (.5" and .75" pipe are at issue.)

Thanks

Reply to
Bennett Price
Loading thread data ...

On 11/8/03 Bennett Price snipped-for-privacy@itsa.ucsf.edu writes in part:

While it will NOT meet UPC code requirements, in my experience a brass nipple does a pretty good job of electrically isolating the black tank of a water heater from copper tubing.

I suppose it would work just as well for a galvanized to copper connections as the material in galvanized or black you're trying to isolate the copper from is iron.

Doug

Reply to
PLUMBGURU2

Perhaps I should have added that the question came to mind since I'm planning a changeout from galvanized to copper in the basement/crawl space of my house but intend to leave the galvanized in the walls.

I'm having trouble getting homeowner's insurance (in California) because of the old galvanized plumbing and am told that a 'substantial' replumbing to copper will satisfy the insurance companies. Water heater is in basement so it will go pure copper; house is 1 story high and the galvanized vertical sections left will be about 4 to 5 feet long.

And as I asked > I've heard that a brass nipple can be used to join copper to galvanized

Reply to
Bennett Price

usually when doing a basement changover and leaving the galv. risers I'd either use a diletric union, a brass ips valve or a min 3" brass nipple. I haven't had any problems over the last 30 years. A simple brass break between the copper and galv. slows down the reaction enough that will out live the existing galv. pipe that is left.

Reply to
kenny b

Reply to
Dale Wilcox

"Dale Wilcox" wrote

Hey guys, the one common thing to all water heaters regardless of the type of plumbing and anode rod materials, or the manufacturers, is the water quality. I've only seen it mentioned what, twice in the whole thread? All water is wet and most of it is clear but that's where the similarities between one location and another cease. Unseen differences in water quality ranges all over the board and you'll find that dictates how well the plumbing/appliance materials it contacts do in regards to their service lives.

Since the EPA changed the acceptable pH range of potable water in 1991 from 6.9-8.5 to 6.5-8.5, most 'city' water has been more acidic. A water with pH 6.0 is 10 times more acidic than a water of 7.0 (neutral) pH. That's not the only thing that will shorten heater and plumbing material life. Things like bacteria, DO, CO2, chlorides, sulfates and TDS content plus chlorine etc. all have a negative impact on material life. Also, electrical grounding and grounds do too.

Take a look here for more info on water caused corrosion:

formatting link
Gary Quality Water Associates

Reply to
Gary Slusser

Like the first gentleman so eloquently stated: Brass is an excellent conductor. So wouldn't it stand to reason that a nonconductive material would break the electrolytic circuit?? how 'bout that PEX! The current will still travel through the water but the intensity of the current is dependant upon the density of the disolved solids in the water (mainly minerals), but its definately better than a metal connector. Make sense?

Reply to
Pipeline9000

If I understand all of this correctly, the issue is not how well a pipe conducts but how electrochemically reactive it is when placed in contact with a pipe of different composition.

I found the following URL's helpful - though they don't directly address the question I posed initially.

formatting link

Pipel>

Reply to
Bennett Price

Dielectric union

My water heater contains galvanized steel inlet water pipes. The house water pipes are copper.

For a test, I did this: - Turned off the gas input valve. - Temporarily disconnected the gas line from the water heater. Then I measured the open circuit voltage and short circuit current across the dielectric union.

Copper Iron ======||||======

Reply to
stan.logue

ross the dielectric union.

emical battery.

ero. A battery "short circuit".

ects across it.

the union indicates that condition.

pipe" into the heater's input gas line.

. No "short", so no current flows.

on water pipe lasts much longer.

s not needed.

per year. It's chemistry.

What a great post this takes away all the hand waving, and gives a real exp lanation why dielectrics don't work in the real world. Virtually all gas l ines are grounded; therefore virtually all dielectrics are short circuited.

So the other way to break the galvanic cell (stop the corrosion) is to inhi bit the conduction through the electrolyte (water), which is done in practi ce by having a several inch plastic lining inside the pipe known as a diele ctric nipple. This effectively makes electrolyte (water) a much poorer con ductor. Hence most water heater manufactures build these in or supply thes e.

Now the other unanswered question is why DOES brass seem to work when put b etween Copper and steel? Theoretically brass should corrode iron almost as fast as copper, but plumber after plumber says putting in brass nipples wo rk, to the point that it has become code in some areas.

Perhaps this just moves the corrosion to just inside the thick large anode protected tank. Since there is no "nipple" failure it appears there is no acute problem. Under this explanation a dielectric nipple would still be preferable and would help the water heater itself last longer.

Does anybody have experience with putting brass between a copper pipe and g alvanized pipe, then opening up some time later? In this scenario the galv anized pipe should still readily corrode.

A more out there idea is perhaps brass forms some natural surface oxidation or other surface layer that acts as an inhibition to the electrolyte simil ar to a plastic liner?

Any other ideas?

Reply to
SandySans

It should be at least 6 inch min.

Reply to
tmansfield1411

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.