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Old 10-27-2020, 01:18 PM   #1
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Hot water heater question

Hi. First post for me, although I've been reading the sage advice from you folks for a couple years now. I have a 24' R-Vision B+ MH.

I "thought" I had a problem with my Atwood GC6AA-10E hot water heater, but then a thread I was reading on this forum led me to double-check my by-pass valves again, and lo-and-behold, I discovered my problem. Duh!

BUT...while I was checking and/or replacing other components in my water heater circuit, I discovered that with my heater switch on, 120V were being delivered to the control box on the back of the tank, but only 99V to the heating element itself. Is this normal? Might I need a new relay or other component? The water is being heated adequately, but I'm still puzzled by this. Any thoughts?

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Old 10-27-2020, 01:34 PM   #2
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Welcome & Good Catch! Your curiosity has saved your from a problem (maybe fire) down the road.

You will need a new control relay - maybe.
You should be able to see the nearly 120vac measured across element if all is correct.

Problems can be in relay itself - burnt / pitted contacts.
Problems can be on black / hot wire going to relay. This is just a spade terminal connection (usually). It may just need cleaning.
Problem can be at breaker box. Bad breaker. You already rulled this out.

I would unplug shore power, turn on switch for water heater electric operation, and use a multimeter to measure resistance - AT THE BREAKER. how? Measure resistance between breaker terminal for water heater and neutral. Water heater element itself will have 10ohms (12amp current, 1440 watts) or 12 ohms (10amp current, 1200 watts). Anything else is something going sideways.

Given relay location is on back of a water heater, subject to frequent heating / cooling, I suspect that the issue is with the spade connection on top of the relay and not relay itself. Start there. Cut it off and put on another 14ga female spade and plug back in. Measure resistance again. if back at 10/12 ohms, then you are good. Otherwise, replace relay.

While you are poking around back there, look for traces of water leaks. Pull foam off if you need to, but in a manner you can put it back. Correct as necessary.
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Old 10-27-2020, 03:06 PM   #3
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Where did you measure the voltage? There will be a voltage drop across the element itself because it is in series at that point. You should be able to measure very-near 120v at the feed to the heater element
Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
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Old 10-27-2020, 03:24 PM   #4
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That DC Relay gets 12VDC via Yellow Wire....closes to allow 120VAC from Circuit Breaker to AC side of relay then from relay to terminal on element
Should be 120VAC at/from Relay and AT terminal on element (Black wires) when measured to ground

With Relay closed and T-stat closed 120VAC being applied to element should measure 120VAC across the Black/White Terminals

Not getting 120VAC thru element then connections are bad or element is faulted
With AC Power OFF check continuity of element
Black to White terminals should HAVE continuity...no continuity element is bad
White terminal to element flange....No Continuity...if you have continuity element is shorted
Is it time for YOUR Medication or Mine?
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Old 10-27-2020, 04:51 PM   #5
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Wow. You guys are great! I'll follow up on your suggestions as soon as I can and let you know what I find.
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Old 10-27-2020, 05:58 PM   #6
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Hi ! Welcome to IRV2! We're sure glad you joined us!

Old-Biscuit gave you excellent advice, as always!

Good luck, happy trails, and God bless!
Joe & Annette
Sometimes I sits and thinks, sometimes I just sits.....
2002 Monaco Windsor 40PBT, 2013 Honda CRV AWD
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