My power direct-vent water heater has a red-letter warning label that says:

VERY IMPORTANT!
WARNING!! CAUTION!!

DO NOT USE DIELECTRIC UNIONS
WHEN HOOKING UP THIS GAS FIRED
WATER HEATING APPLIANCE!
THIS WILL VOID THE WARRANTY!

I did not use dielectric unions, but why would this be a problem?

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Links to the State of Wisconsin Plumbing Code:
[docs.legis.wisconsin.gov]
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I am not a plumber.
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1. They are just cosmetic in the first place
2. The heater probably already has dielectric provision already
3. NOTHING 'voids' the warranty, because when the heater fails NOBODY looks at it to see if there is any reason to "void" the warranty. The heater is replaced and the old one goes DIRECTLY to the scrap yard.

it is that specific?? nothing about any connection with a rubber washer in it? Im curious too. could be a grounding issue?

I forgot to mention it's a stainless tank. No anode rod.

I thought about grounding. But the 120 VAC power provides ground, and the gas line is bonded to the power ground. That is in addition to the hot and cold being bonded to the power ground.


**I edited this to make it clear that the gas, hot and cold are merely bonded to the power ground, not considered part of the grounding system. **

*******************************
Links to the State of Wisconsin Plumbing Code:
[docs.legis.wisconsin.gov]
*******************************
I am not a plumber.
*******************************



Edited 1 times.

but, the gas pipe is(or should be) "bonded" to the grounding system.

Are they still allowing, or requiring that plumbing share electrical system ground? It just brings to mind what has been discussed here before. The danger to plumbers in the event of a Main Neutral Open.



Edited 1 times.

The plumbing is "bonded" to the ground system, but is NOT part of that grounding.

any metallic piping system must be 'bonded' to ground

NOT act as the ground, but, be bonded to ground

a fine point perhaps, but, the point none-the-less

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

So any reason why a manufacturer would say dielectrics void warranty?? Always learning.

Not really, unless he misread the instructions.

I would assume it is because the water heater already has dielectric nipples installed. if you put dielectric unions on top of them, they will eat each other. in nj the hot and cold must be bonded (jumped accross hot to cold), and bonded to ground. it will only take one time of replacing a main valve with an open neutral to know why.... yeah I got that lesson..