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We cut open our Atwood hot water heater

A few weeks ago, we replaced our 2-1/2 year old Atwood electric / propane hot water heater with a new GC10A-4E unit.  Our old unit had developed a leak that messed up the back side and electric heating element, so we decided to replace it.  This time we moved the 120-volt relay that controls the heating element away from the back of the tank, so it could be accessed without removing the tank.  This model uses a 12-volt thermostat to control propane gas valve and 120-volt heating element.

We cut open the 2-1/2 year old tank to learn what happens to the inside in two years, how the gas burner heats the water, how the cold water enters at bottom and hot water leaves at top and how much space is below the drain plug.  Aluminum tank is round and made of sturdy metal thickness.  I was surprised how much debris is in the tank, even though we flush it out every few months.

We plumb the tank hot & cold lines to the water manifold so the lines can easily be closed off and tank bypassed if desired.

Re: We cut open our Atwood hot water heater

Reply #1 –
Very instructive! Our old water heater was still working, so I was hanging on to it intact even though I am installing a new one. Our old one didn't use the relay and the thermostats were in the back. I was happy that the new one has the thermostat in the front and planing to run a new wire to control the relay near the other water heater switch. So there will actually be two switches that need to be on to use the electric side of the water heater. The one on the bed platform and the new relay control. Please explain more about moving the relay away from the back of the water heater, both how and why if you don't mind. Sounds like timely information as I approach that part of my project...

That is a lot of "stuff" in the tank after just two years! Did you ever use vinegar to flush the tank? Thanks for the pictures!
Thanks, Don
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: We cut open our Atwood hot water heater

Reply #2 –
Very interesting, and neat to see what the inside looks like.

I once had a problem with a Toyota Celica running poorly, and was looking for the problem.  I was at the parts counter and was told I had bad fuel.  I said nope, that I had taken the fuel filter apart to check for debris and found nothing in the filter.  The parts guy said, "the filters don't come apart".  I said sure they do, "with a hack saw".  He was speechless, and then smiled and we moved on the other options and ideas.
Dave Cobb
Buckhorn Lake Resort The Club, #6202, Kerrville TX
check the map.  I do rent it out when I am traveling!
2001, U320, 36' #5887, in Kerrville, FT Club #17006, (7/23 to present)
2024 Jeep Grand Cherokee L, Summit, white
EX: 98 U295, 36' #5219, (mid door), (4/13-10/23)
EX: 93 U225, 36' (4/11 to 4/13)

Re: We cut open our Atwood hot water heater

Reply #3 –
Thanks for posting Barry! Interesting that they are so low tech on the inside. :)

see ya
ken
The selected media item is not currently available.ken & dori hathaway & Big Agnes
🍺1992 U300 GrandVilla WTBI #4150 FOT FBP 2011
✨6V-92TA DDEC Parlor Coach 350HP Series 92
🏁2011 Nissan XTerra Pro-4X

Re: We cut open our Atwood hot water heater

Reply #4 –
Barry, what was the cause of the leak, bad weld or bad fitting.
The selected media item is not currently available.Bill&Doris 97 U270 36'
University of Parris Island Class of 66
Semper Fi  Build# 5174 MC#17094

Re: We cut open our Atwood hot water heater

Reply #5 –
Don,

We found the best price ($550) with inexpensive shipping for our water heater at PPL 2-1/2 years ago and last month again.
http://www.pplmotorhomes.com/parts/rv-water-heaters/lp-gas-electric-water-he ater.htm

It uses an electric heating element that screws in from the rear of the tank.
http://www.ebay.com/itm/RV-Water-Heater-Atwood-Heating-Element-Screw-In-Gask et-Included-120V-1400W-/370566314640

The 'new' style Atwood electric hot water heater has a plastic electric connector box on the back of the heater (next to the heating element) that contains a 12-volt relay to control the element. We cut the female end off of a #12 extension cable and used wire nuts to make connections. The heater's control board runs a 12-volt yellow wire to the backside to turn on the relay. 2-1/2 years ago, the ground side of the relay coil was connected directly to the aluminum tank. The extension cord's white neutral was connected to heating element, green ground to aluminum tank & black hot to relay. The normally-open 120-volt relay point was connected to heating element.

The other end of the extension cord's molded male plug is plugged into a bay outlet not on our inverter. Our coach was not built with a 120-volt hot water tank heating element so we did not have the front of bed switch and Romex to tank area. Since you have the Romex, you could hard wire, but we prefer putting an outlet at the end of the Romex so you have a positive disconnect when draining or flushing tank. If heating element is turned on without water in the tank, the element will be destroyed in a moment.

We wanted to have access to the relay without having to remove the hot water tank, so when we replaced the tank last month with the same model tank, we removed the relay from the rear plastic connector box. Running a power cord directly to the heating element also allows us to easily meter the ohms to be sure element is not blown. I also connected a small Radio Shack 120-volt neon lamp in the bay that lights when heating element has power.

I cut a piece off my extension cord, soldered ring terminals on the three wires and connected hot & neutral to heating element and ground to aluminum tank. We could have relocated the relay anywhere, so we chose an open space near our water manifold. I ran the yellow 12-volt relay wire from control board to our new relay location along with a 12-volt ground wire. We made our own electrical connection box from a small snap top clear plastic box we found at Container Store. Cable ends from extension cord & heating element are wire-nutted together in our connection box, hot wires to relay common & normally-open, neutral wires together, ground wires together. Yellow board & ground wires control relay.

This water heater comes with a white inside low-voltage control panel that has gas on switch, electric on switch & gas fault light. We added two small 12-volt LED lamps that indicate when propane gas valve is open & when electric heating element is powered. We use these add-on lights to know when tank is being heated. (When lights are off, we have hot water for a shower) We also changed the original two switches to lighted switches for a better indication when they are on. We ran new wires from tank to the kitchen sink area control panel.

This water heater comes with a different control board than most other water heaters, because of the 12-volt electric heating element relay control.

We used 90-degree Sharkbite fittings & flexible water heater connections for hot & cold tank connections with PEX pipe to water manifold.

http://www.sharkbite.com/usa/product/push-fit-products?page=shop.browse&cate gory_id=3

Re: We cut open our Atwood hot water heater

Reply #6 –
Bill,

As you can see in our photos the top hot water connection leaked where we had a 90 degree fitting. The leak was not cause by a weld at the tank. It was our fault.