New Hot Water Tank

[RAKocher]

This nipple is NOT a dielectric nipple. It simply a plastic lined nipple.

It doesn't make sense, but that's what the manufacturer calls them.

If you want to connect rigid copper pipe directly to the water heater you need to use a section of brass between the steel and copper.

Although I do believe you're probably right and have the fix for this, it still doesn't explain how the cold water side can be completely unaffected or why the manufacturer doesn't require a non-copper fitting be used in their install instructions so they can tell people like me, "You did it wrong, and we can't help you!"

 

[hbiss]

A long time ago I had a water heater inspection done. The inspector gigged me for not having flexible lines, possibly for the reason you are stating. It was too cheap of a fix to ask for an explanation.

I have never seen flex lines on water heaters around here. Neither water nor gas lines. Always hard piped. When you do see them it's always a sign of a DIY job. Flex lines are not used because they deteriorate over time. Granted, with the short life span of water heaters, that may not be an issue if they are replaced each time the WH is replaced. But that never happens.

Maybe it's a requirement in seismic areas?

-Hal

 

[hbiss]

1

 

[curt swartz]

There is no way the nipples supplied with the water heater can be considered dielectric since they do not electrically isolate the pipes.

I just looked up the installation instructions for one manufacture of water heaters and it states to use dielectric unions when connecting directly to copper pipe.

605.24.1 of the International Plumbing Code

Joints between copper or copper-alloy tubing and galvanized steel pipe shall be made with a brass fitting or dielectric fitting or a dielectric union conforming to ASSE 1079. The copper tubing shall be soldered to the fitting in an approved manner, and the fitting shall be screwed to the threaded pipe.

 

[synchro]

...The 3/4" copper female adapters were both sweated onto about 12" of pipe while held in a vise and then washed in a laundry tub. I then used both a couple of wraps of Teflon tape and newly bought pipe dope.on the tank nipple threads and using a 12" crescent wrench made them tight, real tight.

It's possible that you may have overtightened the NPT to tubing adapter since it's made of copper and so is relatively soft compared to the galvanized nipple. Over-tightening could deform the threads so they don't seal as well. They often have a caution on the teflon tape warning against overtightening, because the lubricity of the teflon makes it easy to do. One advantage of having a union above is you can loosen it and then tighten the adapter joint a little more if it leaks, or even completely remove and re-do the threaded joint if necessary.

 

[RAKocher]

Also, how does this setup work if that unpowered water heater is plumbed in parallel with your boiler mate? Won't cold water be diverted through it or do you have it valved off? Water sitting in that thing is ripe for cultivating Legionaries by the way.-Hal

I've done this for 30 years. The cold water supply is tee'd to both tanks and the hot water output is tee'd to both tanks and all valves are kept open. Whichever tank has the colder water (the piggyback tank) it will cause a gravity circulation though the other (the energized, maintaining tank) until the temps of both tanks are near equal. As you use hot water the draw from both tanks is as equal as the resistance to the flow from the tanks is equal. I know it works as I describe because if the primary tank is set to maintain say 120 degree water, the water temperature at the sink or tub is 120 degrees while being supplied from both tanks.

 

[hbiss]

I'm always cautious when using copper female adapters on anything because they do have a tendency to leak even if tightened properly. Doubly so if they will be concealed and pressure test first just to make sure.

-Hal

 

[hbiss]

I know it works as I describe because if the primary tank is set to maintain say 120 degree water, the water temperature at the sink or tub is 120 degrees while being supplied from both tanks.

But have you actually monitored the temperature of the water in and out of the primary heater and the secondary heater while drawing water by measuring the temperature of the pipes? That's the only way to see if your setup is working properly, especially after a drawdown.

-Hal

 

[StarCat]

I would have to agree with the idea that the factory style DE unions are questionable. Take a look at this link which shows both at the Rheem websight. You should notice the copper flex connector has a dielectric member in it:
https://parts.rheem.com/OA_HTML/xxR...tion=18609&section=18609&sitex=10165:52926:US

 

[RAKocher]

It's possible that you may have overtightened the NPT to tubing adapter since it's made of copper and so is relatively soft compared to the galvanized nipple.

I know the cardinal rule of plumbing, "Never tighten a joint all the way, so there's always room to tighten more later if you have to." All that I meant by, "real tight", is just a little more than my normal initial tightening just to be sure, since tightening later won't be possible. I'm the kind of person that will check my plumbing 20 times before I'm convinced that it's fine. Believe me, there is no leak!

 

[RAKocher]

This is what I have on mine. It's a brass Pro Press fitting, done by a plumber only because I let him have the pleasure of humping the old one out of the basement and the new one in.

-Hal

Nice! I bet whoever Rheem sends out will do the same thing to mine... blue dope and all.

 

[RAKocher]

But have you actually monitored the temperature of the water in and out of the primary heater and the secondary heater while drawing water by measuring the temperature of the pipes? That's the only way to see if your setup is working properly, especially after a drawdown.

-Hal

Not very scientific, but I just turned on the hot at the laundry room's utility sink then went around the corner to the hot water tanks and held a hand on the hot water output pipes from both tanks and the primary tank is a little hotter. Which means that the piggyback tank is slightly tempering the combined hot water temperature, but not noticeably.
Also, I used to have a houseful of people living here and the one thing that had always surprised me was how fast the recovery is for the two tanks.

 

[RAKocher]

There is no way the nipples supplied with the water heater can be considered dielectric since they do not electrically isolate the pipes.

I just looked up the installation instructions for one manufacture of water heaters and it states to use dielectric unions when connecting directly to copper pipe.

605.24.1 of the International Plumbing Code

Joints between copper or copper-alloy tubing and galvanized steel pipe shall be made with a brass fitting or dielectric fitting or a dielectric union conforming to ASSE 1079. The copper tubing shall be soldered to the fitting in an approved manner, and the fitting shall be screwed to the threaded pipe.

It's a wonder that the manufacturer doesn't mention that in their installation instructions, especially since they're the one paying for it to be repaired.

 

[LarryFine]

I know the cardinal rule of plumbing, "Never tighten a joint all the way, so there's always room to tighten more later if you have to."

I also routinely do that with conduit. You can always tighten an assembly of pieces more as a group if you need to point in a specific direction. The joint with the least resistance will be the one to turn first, eventually ending up with all of the joints at roughly the same tightness, and not have to loosen any.

When I took SCUBA lessons at a summer camp as a kid (physically, that is), one of our "water aptitude" tests was to assemble pipe parts underwater while holding our breath. The assembly was a 1/2" pipe cap, 1/2" nipple, 1/2" x 3/4" reducer, 3/4" nipple, 3/4" x 1" reducer, etc. all the way up to a 2" pipe cap.

My "secret" to always completing the entire assembly was to only screw each joint together just enough to engage threads, and then twist the entire assembly together with whatever time and breath I had left. The instructor watched me one time, smiled, and agreed to keep my "secret" from the other kids.

 

[synchro]

I also routinely do that with conduit. You can always tighten an assembly of pieces more as a group if you need to point in a specific direction. The joint with the least resistance will be the one to turn first, eventually ending up with all of the joints at roughly the same tightness, and not have to loosen any.

That's certainly a good way to do it. With plumbing there's the added constraint that you don't really want to back-up on any joint after it's tightened or it can be more prone to leaking after tightening again. Usually with conduit you don't have to worry about the electrons leaking out, I don't think.

 

[hbiss]

Nice! I bet whoever Rheem sends out will do the same thing to mine... blue dope and all.

Only if he has a $2000 Rigid Pro Press tool and genuine Viega fittings. (There are a lot of Chinese fitting knockoffs.) And that's blue teflon tape.

I've been drooling over the Pro Press system for a long time, wishing that I could justify the expense of the tool. This plumber I know was happy to give me a hands-on demonstration. No more sweating, no more problems with pipe that won't drain.

-Hal

 

[hbiss]

I would have to agree with the idea that the factory style DE unions are questionable. Take a look at this link which shows both at the Rheem websight. You should notice the copper flex connector has a dielectric member in it:
https://parts.rheem.com/OA_HTML/xxRP...10165:52926:US

The plastic lining in those nipples looks like it's to keep the steel inside of the nipples from corroding and hopefully lasting as long as the water heater. Certainly would nave no dielectric function. I think that's only what they call them.

-Hal

 

[infinity]

The plastic lining in those nipples looks like it's to keep the steel inside of the nipples from corroding and hopefully lasting as long as the water heater. Certainly would nave no dielectric function. I think that's only what they call them.

-Hal

The plastic inside the nipple is a check valve to keep the water flowing in only one direction. There are usually two types flapper and ball style.

 

[ptonsparky]

The plastic inside the nipple is a check valve to keep the water flowing in only one direction. There are usually two types flapper and ball style.

Is that fairly recent? If not, the water heater that was plumbed backwards in my house for 20 years also had failed check valves.

Yes, we never enough hot water.

 

[kwired]

Those short nipples on the WH ports are "heat traps".

Though they claim to also be "dielectric" that is to protect the tank from copper to steel connection, you can still have galvanic corrosion if you connect copper directly to this fitting.