HWT Sludge and Dielectric Couplers

[MasterPlumbersKeymaster]

Have a new (second one trying to solve this problem) Hot Water Tank (HWT) that builds up brown sludge on the inlet AND outlet pipes every few months. The entire tank water goes orange/brown every 3 months. As a result I’m constantly flushing the tank (4x/year minimum). The inlet/outlet pipes actually become occluded with this sludge. The Tank is the second one – It was thought a new tank was bad, but it’s something to do with the plumbing.

The old tank did not do this, but was 14 years old, so I replaced it with a comparable electric Sears 30Gal tank. I used new dielectric couplers, the old tank didn’t have them!! Ohm meter readings are about 1.6 Megohms when the tank is full, from the tank, to water-pipe ground with the electric wires disconnected. Is this a normal reading, or is it low enough to allow some kind of electrolysis to occur and it’s precipitating what I’m seeing? Should I be seeing many many MegOhms or does this lower than expected (to me) reading show I have faulty dielectric couplers?

The cold water tap in this house is CLEAN – there’s nothing abnormal about the water entering the house or the cold faucets. I called the town and asked lots of questions and had a sample sent to them – tests were negative for any particulate or bacteria– so it’s not the town water.

I wrote to this board 8 months ago and tried all the suggestions that were made, to no avail.

[hjParticipant]

Ohms is a resistance measurement. If the dielectric unions were not doing their job, the resistance would be zero. Without water in the tank, the resisance measurement should be infinite. Your reading just shows that water itself carries a part of the current and can also bridge a dielectric union. Next time use brass nipples and see if that stops the process. Any change to the outside of the heater is due to environmental causes, not the water inside it.

[Author]

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