Short WH life...

kcopp

Hi All.
I had a call out to replace a water heater under warranty today.
Typical glass lined tank w/ an anode rod.
I installed it almost 5 yrs to the day.
City water here in NH.
That replaced another water heater that lasted only 3 yrs.
The Di-elec nipple on the hot was severely corroded. The cold looked almost new.
All the std stuff. Potable water extrol, vacuum relief valve. Ran at approx 125F
I looked last time to see if there was an electrical ground issue but noting looked out of order.
I have done plenty of work in this small city over the years and others dont have the same issues.
Any ideas where I should start looking?

STEVEusaPA

What did the anode rod look like?
Did you check for stray voltage on the pipes? H2C, H2G, C2G?

Jamie Hall

First thing I'd look for is stray voltage.

EBEBRATT-Ed

maybe put a copper jumper across hot-cold if you don't find anything else

mattmia2

How did you look for electrical issues? The issue will almost always be with the utility rather than in the house wiring.

hot_rod

The wholesalers and contractors I visit tell me tanks last about or a bit longer than warranty in my area.

Dielectric nipples or connectors used? That should break any electrical currents. I suppose a gas line could transfer stray voltage?

I visited a shop this morning with a metal scrap 10 yard dumpster full of old tanks. Just looking at the labels and jacket you could tell these were not 10- 20 year old tanks.
I believe the metal gauge is thinner, maybe a lower grade import steel? Perhaps a thinner glass coating? New tanks don't seem to be as heavy to lift as I remember.

Water quality, amount of water that goes through them, and operating temperature are some of the common fail factors.

Mad Dog_2

And, as you noted...inferior quality of raw materials and chintzy manufacturing. I know several plumbers that were still doing Lead Shower pans until about 6 or 7 yrs ago.  They are rotting out in a few yrs and when they rip them out its all Orange 🍊 (Ferrous Iron).  Sheet lead was always high quality 99% purity, lead bends too  sounds like China 🇨🇳 and India 🇮🇳 are using Dirty Pig Lead and passing it off as higher grade...Mad Dog 🐕 

Larry Weingarten

Hi, A few more things... is the heater sized for the use they are giving it? If it needs to fire a lot, the likelihood of condensation is higher, if it really is gas fired. Are there any backflow preventers or check valves? Might be good to see if pressure ever gets too high. And the anode will have stories to tell. I'd love to see some photos of it.

Yours, Larry

kcopp

Tank is a 40 gal electric. Has the di electric nipples that come w/ the tank. I did mention to the homeowner about stray voltage and suggested an electrician check this out.
They never did...

Jamie Hall

Fun fact. A dielectric nipple is a wondrous thing. It breaks the electrical circuit between dissimilar metals, and thus at least reduces battery type action. However. If there is a stray impressed voltage on one side or the other of the nipple, a current will flow... through the water... and severely corrode one side or the other (both, if it's AC) of the mipple.

Something isn't properly bonded or grounded.

ChrisJ

EBEBRATT-Ed said:

maybe put a copper jumper across hot-cold if you don't find anything else

I always thought this jumper was required by code?

Jamie Hall

ChrisJ said:

EBEBRATT-Ed said:

maybe put a copper jumper across hot-cold if you don't find anything else

I always thought this jumper was required by code?

If not it should be. In fact, in my humble opinion, all metal piping should be bonded together and grounded somewhere... but that's me.

mattmia2

Jamie Hall said:

ChrisJ said:

EBEBRATT-Ed said:

maybe put a copper jumper across hot-cold if you don't find anything else

I always thought this jumper was required by code?

If not it should be. In fact, in my humble opinion, all metal piping should be bonded together and grounded somewhere... but that's me.

I think technically it is required in a clause in the nec but there are exceptions that allow the appliance to be that bond.

pecmsg

But, there's nothing wrong with grounding the 2 lines as a precaution!

EBEBRATT-Ed

Putting a jumper from hot to cold will not eliminate the problem but for a small cost may reduce the problem, Morestray current will cross the copper jumper, but some will still flow through the water heater although the wh with steel nipples and a steel tank will be more resistant to flow

ChrisJ

EBEBRATT-Ed said:

Putting a jumper from hot to cold will not eliminate the problem but for a small cost may reduce the problem, Morestray current will cross the copper jumper, but some will still flow through the water heater although the wh with steel nipples and a steel tank will be more resistant to flow

So what you're saying is pex is a must if you want to guarantee there won't be an issue, ever.
At least, at some point to break the circuit.

Obviously it's not allowed near drafthoods and some locations don't allow it within a certain distance regardless of WH type.


That said, the resistance through a 4 gauge copper jumper should be substantially lower than through the steel nipples and tank, so it should reduce the issue a lot.

GroundUp

Things like this make me feel fortunate to be in an area where the water quality must be pretty decent. I'm on well water at home and am still running the same cheapo Richmond natural draft LP tank installed when the house was built in 1995. My parents 2 miles away are still on the original 1984 Rheem electric tank. Neither of them have ever been flushed. The nearest town with city water, I removed a 1992 model NG tank that was still operating fine in favor of a mod/con boiler and indirect.

mattmia2

ChrisJ said:

That said, the resistance through a 4 gauge copper jumper should be substantially lower than through the steel nipples and tank, so it should reduce the issue a lot.

The conductivity of copper is higher than that of steel but the cross sectional area of the steel is greater so the resistance of the path through the steel may be less or at least close enough to that of the copper that a significant percentage of the current follows the steel. Dielectric unions will isolate it with plastic inserts but it is still connected to the gas piping and/or the electrical system.

Jamie Hall

and if the circuit is broken, as with a dielectric union, and there is an impressed voltage, the current will flow anyway -- though the water, thus corroding the pipe... dielectric unions are just dandy -- provided there is no impressed voltage from somewhere else.

JUGHNE

Somewhere in the NEC it states that all piping and ductwork that has the possibility of being energized shall be "bonded" to the electrical grounding electrode system.

So attempting to do that in my basement, I have #4 copper (old stock shorts) bonding the hot, cold, boiler hydronic copper supply and return, gas pipe.
The grounding electrode consists of 120' of 1" copper service line connected to iron water mains. The water meter is jumped. Also a ground rod at the house and again at the pole mounted electric meter.

I guess I am lacking in bonding ductwork, the 2 AH's are grounded but the supply duct has canvas connectors.

The idea of the bonding is if any metallic conductive parts become energized then a breaker should trip or carry away any current to the grounding system.
The bonding wire size is determined by what the largest conductor in the area is.
A #6 will cover just about anything.

mattmia2

Corrosion on the outside is from a leak or possibly chemicals from flux or something and condensation.

EBEBRATT-Ed

@kcopp
the first thing i would have an electrician check is for an open or loose neutral. That will cause current to flow through the grounding electrode conductor to the metal water pipe or ground rod and if that ground connection is compromised then it's a crapshoot and any metal water lines could have stray current on them

kcopp

Thanks guys.
This is great info.
I have the homeowner getting an electrician over.

STEVEusaPA

kcopp said:

Thanks guys.
This is great info.
I have the homeowner getting an electrician over.

If you could, let us know what, if anything, was finally found.