Latest Discussions : Plumbing

newatthis

08:14PM | 06/10/04
Member Since: 06/09/04
2 lifetime posts
Hi. My first message. Don't even know how to begin to keep it short. (Getting to the point would help I guess.)

Anyway, for my first plumbing project, I'm trying to install a recirc line pump on my water heater's hot line.

I cut the pipe, but have had no luck loosening or even "budging" the 3/4" threaded adapter right at the water heater. Have tried hammering a wrench against it. Then brought in 2 guys with a little more muscle than I have. (And yes, we were all going counterclockwise.) Have tried penetrating spray...even WD-40. Then my ex tried a bit of propane since it looked like solder had "dripped" in when the line was installed. Now it's really a mess. The adapter is just about stripped. Probably have done other damage. Is there any miracle or am I looking at replacing the water heater...which is only 2 years old?

Please help!

tomh

10:28PM | 06/10/04
Member Since: 07/01/03
549 lifetime posts
I guess that someone forgot to install the flex supply lines with a dielectric union. Hot water tanks are notorius for galvanic corrosion that occurs when steel or copper is directly connected to the tank. A dielectric union should always be used. Without it, the tank supply lines essentially fuse (rust) to the tank and you cause damage to the tank connector when you try to remove the supply lines, or eventually have leakage from the top of the tank at the fittings.

I don't know how to advise you once this has already occurred, but if you replace the tank, don't allow the same mistake to occur again. Install the dielectric union first, then sweat the fitting to connect your flex lines to that. Your plumbing supply will be able to provide the unions if you get the old supplies off, or if you end up buying a new tank.

newatthis

07:51AM | 06/11/04
Member Since: 06/09/04
2 lifetime posts
Hi Tom. Thanks for your help. Actually there were no flex supply lines at all, even though the heater's manual recommends it exactly for this reason. And I didn't really see any evidence of Teflon tape at that copper fitting (but I guess he might have used paste?).

Anyway, it looks like a new water heater might have to happen. If it does, does the heater itself have a steel female union? The supply store sold me a brass 3/4 x 2 1/2 RB nipple to seat my Grundfos pump on. I was told that Teflon at each of the connections will be sufficient (and there are quite a few unlike links in this line.). Is this true? And since I want to be absolutely correct about it, does it matter whether it's wrapped once around or several times? Or should I still use a dielectric union right at the heater?

I am concerned about the weight of the pump and the amount of fittings it'll sit on since flex pipe will be above it.

Thanks again in advance.

tomh

08:38AM | 06/11/04
Member Since: 07/01/03
549 lifetime posts
The dielectric unions are installed right at the tank. Without them, the electric differential between copper pipe and the steel tank parts quickly creates the corrosion problem you are now familiar with. The flex connectors attach to that union, and your circulation pump is attached between the flex and house plumbing. The brass fittings can be sweated in place and used, the pump, brass fittings and copper pipe should not require a dielectric union.

Flexible connections are used because of seismic concerns and normal movement of the tank and plumbing. They also allow for pipes to be more easily attached as they are tolerant of imprecision for DIY plumbers like me. They are code in many locations. You should call your local building department to ask, but I always include them because its easier.

Teflon tape or (my preference) teflon paste should be used at all threaded unions and fittings. It prevents leaks and makes dissassembly easier later. We had a solar hot water system that used a Grundfos pump to circulate water to the collectors. So, I have some familiarity with the situation. Someone else may comment here, but a back-flow valve might also be a good idea between the tank and the pump.

BV017479

08:34AM | 09/23/18
On my old gas water heater it has steel pipes on the cold side steel coupling came off with no problem on the hot side the steel coupling was threaded on like cross threading now I can't get the steel coupling loose .....help


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