Atwood gas/electric water heater question

rockelino · 12-19-2020, 02:18 PM

Rig: brand new Winnebago Micro Minnie 2405RL (fifth wheel, very small and lightwieght).

Issue: Atwood (now called Dometic) 6 gallon water heater won't turn on.

OK, so at first, I tried the electric function of the heater. The light (at the switch area) turns on, so I figured it's working. 1 hour later I tried the hot water - I know the hot water tank is full and all the valves are in the correct position. Only cold water.
I turned the electric water heater off and tried the LP function. No pilot light, no hot water. All circuit breakers/fuses are OK.

Update: I troubleshooted some of the connections/wiring and made the LP function work - after reinforcing a certain wire connection (wire is brown in color) the pilot turned on, now I have hot water!

Question: how do I get the electric function of the water heater work? The model number is GC6AA-10E

I called the dealer (we just purchased it in early November), but no luck, their service department is "too busy to help us right now."

**creativepart** · 12-19-2020, 05:28 PM

Sounds like you improved the Thermal Cutoff's wiring connection - did you remove that cutoff diode?

Here's the detail. There is a brown wire that is a 12v power connection between the circuit board and the water heater at the ECO and T-Stat location. This is a fail safe for when the propane burner has a blockage and heat builds up inside the water heater housing.

The thermal cutoff is like a fuse that breaks the circuit when it gets too hot. Once the cutoff is activated electronically by heat the water heater cannot work in Electric or LP modes.

If you remove the diode section (it's a clear plastic tube with what looks like a resistor inside) everything will start to work again. The system is set up to easily bypass the cutoff by simply unplugging the wire going into the cutoff and reattaching it directly to the tab on the housing. But you should not run the WH on propane until you are sure that there is nothing causing the burner to overheat. It should work fine on electric, but it will take a lot longer to heat the water.

These are common points of trouble. They are sold everywhere RV parts are sold. However, they usually blow for a reason and that reason should be corrected. I say "usually" but not always. On my RV mine has blown 5 times in 3-years and the only fix was to move it further away from that standard location. This was easy to do because when you buy a new one they provide an extension wire in the packaging.

https://www.amazon.com/Atwood-Produc.../dp/B0007XXTVC

Here's of photo of the wire and thermal cutoff.

rockelino · 12-19-2020, 05:37 PM

Quote:

Originally Posted by creativepart

Sounds like you improved the Thermal Cutoff's wiring connection - did you remove that cutoff diode?

Here's the detail. There is a brown wire that is a 12v power connection between the circuit board and the water heater at the ECO and T-Stat location. This is a fail safe for when the propane burner has a blockage and heat builds up inside the water heater housing.

The thermal cutoff is like a fuse that breaks the circuit when it gets too hot. Once the cutoff is activated electronically by heat the water heater cannot work in Electric or LP modes.

If you remove the diode section (it's a clear plastic tube with what looks like a resistor inside) everything will start to work again. The system is set up to easily bypass the cutoff by simply unplugging the wire going into the cutoff and reattaching it directly to the tab on the housing. But you should not run the WH on propane until you are sure that there is nothing causing the burner to overheat. It should work fine on electric, but it will take a lot longer to heat the water.

These are common points of trouble. They are sold everywhere RV parts are sold. However, they usually blow for a reason and that reason should be corrected. I say "usually" but not always. On my RV mine has blown 5 times in 3-years and the only fix was to move it further away from that standard location. This was easy to do because when you buy a new one they provide an extension wire in the packaging.

https://www.amazon.com/Atwood-Produc.../dp/B0007XXTVC

Here's of photo of the wire and thermal cutoff.

Wow, thanks for the awesome reply.
I did not remove the the cutoff diode, all I did was pressing that brown line connection (the second "BRN" from the right, in your image) to the left and that ignited the pilot. After posting my original post, I turned the electric heater (LP function switched off) and long and behold - the electric heater works. I don't know how pressing that brown wire connector fixed it but now both functions work. I just hope it doesn't fail again, knowing that the dealer isn't going to help me with this anytime soon.

**creativepart** · 12-19-2020, 06:48 PM

That other brown wire is from the T-Stat... thermostat. It is also a temperature fail safe. when the water in the tank gets too hot it expands and breaks the electric connection. So, perhaps all you had was a loose wire. Nothing more.

The T-Stat is an inexpensive part and easy to replace if need be. The ECO and TStat come packaged together for something like $30. They simply screw in and touch up against the aluminum tank to perform their operation. And, yes they will "kill" the power to the control board if they sense incorrect temps.

I doubt your problem was anything but a loose wire. You may want to squeeze that connector with a pair of needle nose pliers to insure a tight connection. If need be.

imnprsd · 12-22-2020, 06:42 PM

Sometimes you just need to peal back that black protective square (tape) to inspect for oxidation under the Thermo & ECO spring loaded safety switches... then clean the contact points with sandpaper (metal sand paper is preferred over wood sand paper).

Note: You will also see these spring loaded contacts have an insulation plastic spacer that you need to rotate (precariously under the metal tabs) into proper position it or your switch will not work.

These spring loaded switches are normally closed thermal safety switches that make a serial connection. This means you an use a jumper to bypass the switch in order to diagnose if the switch is bad or not.

All that said, my guess is that when you messed with the "brown wire" you moved the switch just enough so the contact with the tank was improved.

Therefore, you still have work to do -- clean the bottom side of the switch where it meets the tank or you will be without hot water again soon.

This diagram is specific to my Atwood A10-4E (10 Gal) Water Heater, but the function of these to spring loaded safety switches is common to all.

Also, that brown wire thermal-diode fails more often than you think and many people carry a spare, and a spare set of tank sensors, because you know these things will fail while you are camping! (So who you gonna call then?) I.e., having a spare set is not just about making sure your DW gets a hot shower... it's also to make sure you can get a hot shower too!

Note: If you use a jumper to heat your water be careful not to overheat your tank. Just 5 minutes should heat the water enough to take a warm shower. Then turn the power off and remove the jumper. Never leave the jumper connected... unmonitored.

One more thing: Some people think their hot water circuit is faulty if they do not have hot water. And they get really confused when they know there is hot water in the tank as evidenced buy pulling the tank water pressure switch.

Consequently, if you know you hot water in the tank an it has reached a temperature of 140F, then your problem is most likely a stuck check valve screwed into the back of your tank. ...And you may have one or two check valves, but it's usually the hot water check valve ON THE TOP that is the problem.

To fix a stuck Camco check valve - just remove it (if you have a big enough wrench) and then drill out the check valve and turn it into a pipe nipple. Then reassemble.

You do NOT need a check valve for your hot water to work. These Camco check valves are junk and cause a number of owners to end up without hot water for days.

Plus if you drill out the guts of that Camco check valve you will save yourself a $200-$250 repair bill.

A much better place to install a check valve is just before your hot water "T" to the shower line... where the hot water tank water line goes to your bathroom sink.

Read this for more information on where to install a shark bite check valve and why:
https://www.winnieowners.com/forums/...ue-359595.html

rockelino · 12-22-2020, 06:52 PM

Quote:

Originally Posted by imnprsd

Sometimes you just need to peal that black protective square (tape) back to see the two spring loaded devices (Thermo & ECO) that touch your tank... and then clean the aluminum/steel tank contact with sandpaper (metal sand paper is preferred over wood sand paper).

Note: You will see that these spring loaded contacts have an insulation plastic spacer that you need to rotate (precariously) into proper position (under the metal tabs) or your switch will not work.

These spring loaded switches are normally closed thermal safety switches that make a serial connection. This means you an use a jumper to bypass the switch in order to diagnose if the switch is bad or not.

All that said, my guess is that when you messed with the "brown wire" you moved the switch just enough to make contact. So cleaning the bottom side of the switch and the tank is my recommendation or you will have a repeat problem soon.

This diagram is specific to my Atwood A10-4E (10 Gal) Water Heater, but the function of these to spring loaded safety switches is common to all.

Also, that brown wire thermal-diode fails more often than you think and many people carry a spare, and a spare set of tank sensors, because you know these things will fail while you are camping! (So who you gonna call then?) I.e., having a spare set is not just about making sure your DW gets a hot shower... it's also to make sure can as well!

Thanks for the info. You'd think with a brand new RV, I wouldn't have these issues, thanks dealer!

imnprsd · 12-22-2020, 08:04 PM

True, but for over 30 years RV have been using this design and for good reason. There are a few short comings to the Atwood water heater, and we just covered them, but overall when you examine almost RV systems you will find most designs are based on very simple principles grounded in physics... and for good reason. The road is mighty tough on electronics! So sometimes the less solid state the better!

That water heater board is a PITA for this reason and it's not cheap.

Also, access to the back of the water heater is often a nightmare, but some coaches did a good job thinking about this.

As you learn to work on your RV you will find you can afford it. So keep asking questions. It's the only way to learn. ...And it gives some us RV retired enthusiasts something to do.

PS... Anything written by "Old Biscuit" about water heaters or any other subject for that matter on www.IRV2.com is usually golden!

stoney1 · 12-23-2020, 01:37 PM

Quote:

Originally Posted by imnprsd

True, but for over 30 years RV have been using this design and for good reason. There are a few short comings to the Atwood water heater, and we just covered them, but overall when you examine almost RV systems you will find most designs are based on very simple principles grounded in physics... and for good reason. The road is mighty tough on electronics! So sometimes the less solid state the better!

That water heater board is a PITA for this reason and it's not cheap.

Also, access to the back of the water heater is often a nightmare, but some coaches did a good job thinking about this.

As you learn to work on your RV you will find you can afford it. So keep asking questions. It's the only way to learn. ...And it gives some us RV retired enthusiasts something to do.

PS... Anything written by "Old Biscuit" about water heaters or any other subject for that matter on www.IRV2.com is usually golden!

Yep, agreed and in my experience when it comes to RVs, creativepart may be the most knowledgeable person I've seen posting here.

Upinsmoke · 12-28-2020, 01:25 AM

To echo what Stoney 1 said, this is just a (almost) New Year shout out to Creative Part, imnprsd, Old Bisquit vis iRV and the other knowledgeable and giving unsung posters on these forums.
You all have helped me previously a couple of times, and I try to return the favor when possible.

THANK YOU!

chrisking · 12-28-2020, 07:49 AM

I had this problem and the camper next to me told me to light a burner on my stove first & leave on 1/2 minute or so then turn off and retry water heater- it worked. He said it just needed to be Burped!