Community Forums

jvannghi · 09-29-2024, 05:15 PM

Hey Guys,

First off, wanna say thanks always for the ppl here, I don't come on often and so many always willing to help my disaster of an RV. thank you so much!

So last time out, my pressure relief valve was leaking, it was just dribbling out. Obviously it could be just bad and need replacement but problem is, I tried turning it off at the control panel inside and it would NOT turn off. I could hear/see it on, heating the water. Only way to shut it off was to turn off at the circuit breaker.

So question is, why didn't it turn off at the console panel above the driver? Is the thermostat bad or is it cuz the heater wouldn't shut off causing it to continue creating pressure and started to release at the pressure valve?

I could change the valve no problem but I figure it's cuz it won't shut off and I don't know/understand the circuitry for this.

I haven't done any maintenance to it except change the anode. Open to doing whatever needed to maintain/fix it. I seen this, not sure what I would need.

https://pdxrvwholesale.com/products/...tune-up-kit%20

It's in my 01 Fleetwood Expedition 36T if that matters.

Thanks again!

Old-Biscuit · 09-29-2024, 08:40 PM

A few questions:

The AC doesn't shut off?
*How do you know it didn't turn off? (monitor Amps etc)

What anode rod -----Atwood has never used one. They use aluminum tanks that do not require an anode rod
Atwood uses a 1/2" Nylon Plug (not that anode rod with pet cock)
*Suburban does due to the Steel glass-lined tank

Unable to turn off
Could be the control switch

Both t-stats would have to FAIL closed to overheat on your standard model
T-stat Opens at 140*F/ECO (Hi Temp) trips at 180*F and locks out all heating
**On Gas the ECO triggers Fault Light
**On AC the ECO has to be Manually Reset (hole in cover on backside of tank)

T&P Relief valve can 'weep' due to:
*Loss of air pocket in top of tank
*Old and/or build up on valve seat/disc
*Temp reaching 210*F or pressure reaching 150 PSI

Loss of Air Pocket:

2001 Vintage........Relief Valve is 23+ yrs old
Replace it
Could be 1/2" NPT Relief Valve OR 3/4" NPT Relief Valve
*Atwood used both sizes (remove yours/take with to Hardware Store/Big Box Store----4" temp probe)

PDX is good place to shop/compare parts
Except for the T&P Relief Valve----All components in your pictures are for GAS Functions ONLY on the 3E Version (outside compartment)
*AC components are under cover on backside of tank

Atwood 3E Version was last used in 2003
It used 12VDC for Gas Function and the Electric was separate with 120VAC direct (own set of 120VAC T-stats)
*Sounds like the RV MFG installed a Control Switch inside RV for the AC as the OEM switch is on backside of Tank

DFord · 09-29-2024, 11:06 PM

I had the same thing happen to me while my MH was sitting in the driveway. I wasn't even using the water heater! I leave it plugged in to keep the batteries charged. I did some work inside (nothing to do with the water heater!), went inside for supper and when I came back out, I heard water boiling in the water heater right next to the entrance door! I opened the cover to find the relief valve wide open because of the heat. I checked my switches and both the gas and electric were off and had been off for a couple of weeks since our last outing. Good thing I'd forgotten to drain the water heater! Like you, I had to turn the circuit breaker off to stop the runaway heating element.

What I found was the itsy-bitsy relay on the back side of the water heater had welded its contacts closed. That's the only thing that interrupts power to the electric heating element. The control board sends 12 power to the coil which closes the contacts - until the weld themselves together.

I also found one of the wires to the heating element must not have tight enough and overheated burning back a couple of inches and ruining the electric element.

There should be a thermostatic safety switch in the 120v wire to the heating element. Shame on Attwood for not doing that. They're out of business now so you can't fuss with them anymore.

I forget where I bought the parts to fix it but it wasn't Attwood. I replaced the relief valve, the relay and the heating element. Using the numbers off the relay, I was able to find it and everything else I needed on Amazon I think.

I had an old thermostat from an electric water heater laying around so I used some J-B Weld to stick it on the top of the tank and ran the 120v wire through it for safety's sake.

jvannghi · 09-29-2024, 11:12 PM

Thx for the reply, lots of info, will take me some time to check all this

I didn’t try and turn off AC or main switch, I needed it at the moment while in the desert, I have a water heater switch, I turn on/off as I use it to shower. I knew it didn’t turn off cuz it’s blowing out the pressure valve, I turn off switch and still hear the burner going and continues to dribble out of valve. I guess it may have been weeping as u called it, it wasn’t blowing out really hard, more of a decent amount of dribble.

There a rod on the bottom of the tank, just got a small aluminum one to replace the existing that was corroded to nothing. Straight swap.

If parts are old and easily replaced, I’ll just do it to eliminate and narrow down the problem.

Can I change control unit, pressure valve and both t stats easily? Anything else to change while at it?

Thx so much!!!

Quote:

Originally Posted by Old-Biscuit

A few questions:

The AC doesn't shut off?
*How do you know it didn't turn off? (monitor Amps etc)

What anode rod -----Atwood has never used one. They use aluminum tanks that do not require an anode rod
Atwood uses a 1/2" Nylon Plug (not that anode rod with pet cock)
*Suburban does due to the Steel glass-lined tank

Unable to turn off
Could be the control switch

Both t-stats would have to FAIL closed to overheat on your standard model
T-stat Opens at 140*F/ECO (Hi Temp) trips at 180*F and locks out all heating
**On Gas the ECO triggers Fault Light
**On AC the ECO has to be Manually Reset (hole in cover on backside of tank)

T&P Relief valve can 'weep' due to:
*Loss of air pocket in top of tank
*Old and/or build up on valve seat/disc
*Temp reaching 210*F or pressure reaching 150 PSI

Loss of Air Pocket:

2001 Vintage........Relief Valve is 23+ yrs old
Replace it
Could be 1/2" NPT Relief Valve OR 3/4" NPT Relief Valve
*Atwood used both sizes (remove yours/take with to Hardware Store/Big Box Store----4" temp probe)

PDX is good place to shop/compare parts
Except for the T&P Relief Valve----All components in your pictures are for GAS Functions ONLY on the 3E Version (outside compartment)
*AC components are under cover on backside of tank

Atwood 3E Version was last used in 2003
It used 12VDC for Gas Function and the Electric was separate with 120VAC direct (own set of 120VAC T-stats)
*Sounds like the RV MFG installed a Control Switch inside RV for the AC as the OEM switch is on backside of Tank

DFord · 09-29-2024, 11:18 PM

As Old-Biscuit says - Attwood does NOT use an anode rod. Throw it away and get the standard 1/2 inch plastic plug.

Old-Biscuit · 09-30-2024, 12:39 AM

OP's 3E version does NOT have the relay/set up like DFords 2004 Vintage which was 1st year Atwood combined the AC/Gas to DC controls

You stated I turn off switch and still hear the burner going and continues to dribble out of valve

Gas uses 12VDC for control...........burner not shutting down when you turned switch OFF
Suspect the Switch is BAD
As I stated earlier........both the T-stat AND the ECO would have to fail CLOSED in order for DC to go to Gas Valve solenoids keeping them open so gas continued to flow/burner and cause T&P Relief Valve to weep (dripple)
Your water temp would have been scalding!

The rod at bottom of tank........someone (previous owner?) changed out the OEM Nylon plug to that anode rod

PDX Warehouse has all the parts ----- easy DIY

jvannghi · 09-30-2024, 03:58 AM

Thx for all the replies, will have to check all that.

I’ve seen lots of posts in this heater but not totally clear. Is there an exact straight swap available for the setup I have or just better to fix it?

If it’s not horribly costly and direct replacemn is available , I wouldn’t mind just replacing and calling it done.

Greatly appreciated!

DFord · 09-30-2024, 11:06 AM

Attwood was bought out by Dometic. They do not offer a similar size replacement. Dometic's new model is not a good fit as a replacement. I've heard Suburban may have something that's a better fit.

Old-Biscuit · 09-30-2024, 11:47 AM

Dometic redesigned their new line on 6 & 10 gallon models
Narrower/taller/deeper then the Old Atwood

Atwood GC10A-3E cutout dimensions
16" H x 15-1/2" W x 20-7/8" D

Suburban SW10DE
16 3/8" H x 16 3/8" W x 20 1/2" D

Dometic WH-10GE dimensions
Cut-out: 15-3/4"H x 16-1/4"W x 20-10/16"D