DIELECTRICS IN A HOT WATER Heater

mobiledynamics

hi -

I've been hemming hawing on how to plumb the inlet/outlet on my new HW tank.
Year 5, I replaced the anode rod. It had plenty of life left on it.
In April of this year, it would have been year 8.
This was what I discovered on the tank side of the hot water outlet nipple : Brass Nipple I just removed. It's about 85% plugged, 1/4 thick, and I'm not sure if that is from the rod or from the tank.



Regardless, I thought a brass nipple was the better method of install off the tank.

New tank in place, with shark bite hoses for a temp hookup.

Thinking on Ridgid tie in. Stock galvanized nippled, 3/4 brass coupler, 3/4 Bronze Male-Copper adapter (Viega Press Male to CU) . CU tie in to house lines.

Option 2 is just a CU flex line back to the house lines.
Everyone seems to say the flex lines have di-electric built in. When I look at the CU flex line, aside from the brass nut, and washer, it's just a 2 inch pex linining on both ends of the flex line.

Anyhow, was blown away by how much corrosion on saw on the nipple that I'm not sure what is the correct best practice to plumb this thing up


https://www.dropbox.com/s/n0hayg5siq306gd/clog.png?dl=0

Mad Dog_2

I usually do my water heaters with Red Brass unions or Copper x Male or female unions right on to the water heater nipples.  Dialectrics are fine, but aren't necessary in many cases, and they are NOT cheap.  Mad 🐕 Dog

Larry Weingarten

Hi, My preferred method is to use plastic lined steel nipples in the tank, and from there go with copper or stainless flex connectors as long as they have real dielectrics built into their ends. This means the rubber washer inside of the nut and a plastic bushing visible between the nut and tube. If you use an ohm meter between the nut and tube, you should get no continuity.

I'm not fond of dielectrics as they often clog up with rust. Brass nipples into the tank become one more thing for the anode to "see" and protect, so they can clog up in conductive waters. In clean, not too conductive water, brass seems to work just fine.

Yours, Larry

mobiledynamics

In looking at the construction of the CU flex hose I have
Brass Nut
Rubber Washer / Looks like 2" Pex Liner/Bushing on the ends of the flex copper. The water will see the copper flex past the 2" Pex Liner on the end of the nut.

With that said, would this be the same if I did the following

Stock Line Galvy Nipples (lined)
3/4 Red Brass Coupler
3/4 Male Bronze (viega propress) fitting and then ---->Copper Hardline

Larry Weingarten

Hi @mobiledynamics , If I'm understanding right, you would go from galvanized steel directly to brass. Brass will attack the steel once the zinc is gone, so I don't see this as a long-lived approach. Starting with a lined steel nipple in the tank might do it though. It also would put distance between different metals, which matters.

Yours, Larry

mobiledynamics

Sorry, I presume you guys presumed the same. The stock tank nipple is lined. The liner only lines the ID. It doesn't -wrap- cover, the lip of the face of that thread.

I think the only difference I can see is if I use a brass coupler, even though the stick factory nipple is lined - the top of the nipple will be exposed to H20, if I used a brass coupler.

If I did the flex hose route, that would be sandwiched/covered by the washer. Maybe there is some water that may permeate through that washer, but that would be a macro micro level ?

I dunno. Flex just looks so -cheap- to be vs a ridgid tie in.
Maybe that rubber washer is the key to all of this....

When I go searching for info, lotsa recommendations to replace the galvanized nipple with Brass.
Needless to say, my pic speaks for itself though.....

Larry Weingarten

Hi @mobiledynamics , Here's a picture of the bad and the good with lined nipples. You don't want the kind on the left. If you can get the kind on the right, that's what I'd use. So much has to do with water quality. With good, not too conductive water, brass and steel get along peacefully. Not so in more conductive or aggressive waters.

Yours, Larry

mobiledynamics

Oh I see, on the right.....which I honestly don't know how it looks on the new tank....just got it all tied up and fired it up *knowing I was going to revisit the final plumb up as I needed to do research - after seeing the corrosion on the brass nipple I removed off the old tank. However, this nipple was directly on the tank (removed the stock lined nipples on install)

Still wondering the corrosion I see if simply just from the anode or is it from the tank


So if it looks like the right, I think I will go as planned and go with the brass couplers.

Unless I am looking at this wrong, the brass couplers - ridgid tie in, would still be the same die-electrically wise as the flex lines.

Everyone seems to say the flex lines are -dielectric built in-, but aside from brass nut, washer, and just the 2 inches or so of Pex Bushing/Lining on the ends of the fittings, it's nothing more than that

Larry Weingarten

Hi a true dielectric will not pass current. Using an ohmmeter will tell you if it's a true one. That said, a dielectric fitting is real, but the gap between brass and electro-galvanized steel is only about an eighth of an inch. This bridges over pretty fast with rust, so there isn't much benefit. A reason I like to go up from the tank with a lined nipple and then to a flex connector is that the steel in the tank and the copper flex connector are separated enough so there is essentially no bad effect on the steel from the copper. The normal three inch lined nipple is enough. Putting brass into the tank mixes metals. Using a brass union on top of a lined nipple does not give you a true dielectric, but still protects the tank pretty well because of the nipple. Am I making sense or just muddying the waters?
Also, when a brass nipple is put into a tank, two forces come into play. The galvanic corrosion that happens between brass and steel may build up a rust blockage at the joint and the anode will see the brass and try to protect it as it's quite noble to aluminum or magnesium. This will build up a blockage of hardness from the water. Flow gets restricted either way.

Yours, Larry

mobiledynamics

I had to rehash it twice and yes, you are making me second guess if the small *gap* between lined nipple/brass coupler is not as *good* as a flex connector with the washer on direct contact /mating surface.

I'm sure you have seen it -all- to know which one is the better route to go.

Larry Weingarten

Hi, It all depends on the water, and the goals. I try to get fifty years from glass lined tanks, with regular maintenance of course. An exterior leak can kill a tank in about six months, because it isn't protected at all and modern tanks are made with relatively thin steel compared to how it's been done in the past. If the water is conductive/hard, I'd make sure there was no way it could get to steel. Demon rust is persistent!

Yours, Larry

mobiledynamics

50 Years Is that with dual anode rods on a new install or a powered anode rod to start

In my other house, the copper tank heater croaked around 60 years. This was based on roughly how old my neighbor was and the age of the house. My memory ain't as good as it used to be, but now you got me thinking on what its demise was.

Eh, based on the last 2-3 threads, I think I'm going back the flex route. I get the whole washer/bushing on the flex......but call me old skool. Ridgid tie in just look cleaner.