Electric Element in Water Heater Running Wild

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Moonwink
Posts: 14
Joined: Sun Oct 27, 2019 7:46 pm
Location: Near St Louis, MO

Electric Element in Water Heater Running Wild

Post by Moonwink »

Atwood GC6AA-10E in a 2004 Trek acting up

On the last morning of our 3 month winter getaway in the same spot as we were eating breakfast I thought I smelled something electrical burning. As I was outside readying to pull out, the wife discovered it coming from the cabinet with the water heater in it. I flipped the switch off over the door and finished getting ready to go. On the way home we used the propane burner without any issues. It turns out the wire on the electric element burning wasn't the only problem - I haven't pinned it down yet but somehow the element heated up after about 2 weeks sitting in the driveway at home for no reason at all. I caught it running wild one evening (I keep the MH plugged into a 15a extension to keep the batteries charged). I'd been inside making the bed a couple hours earlier and didn't notice anything wrong - good thing I went back out later on when I remembered I hadn't drained the water heater. The WH is right next to the door and as I unlocked the door, I heard water boiling and felt heat coming from the water heater. There was no pressure on the system because I had the low point drains open. The water was boiling without building up any pressure. I raised the relief valve right after I flipped the circuit breaker off (which I should have done right at first). I noticed there was no tension on the relief valve meaning the heat had raised it off its seat. When I drained the rest of the water out, it burned the grass where it hit the ground. I've got a new element although on inspection and testing, there was nothing wrong with the old one except for were the wire with a bad connector attached had it melted the insulation back about 3 inches. I also bought a new relay because I suspected the old one had welded contacts (upon testing, the relay is good). Something was letting power through to the element when I found it overheating and the relay is the only thing I can think of that would have done that. The switch over the door should have killed power to the relay coil.

So now, I'm worried about why there was power to the element when the water heater was so hot. Looking at the 2003 service manual (attached) it appears the relay is controlled by the control board. The thermostat and ECO feed into the control board instead of directly breaking the circuit to the relay. If that's the case, I think I'd better replace the control board because it clearly didn't stop power from getting to the relay when it should have unless someone else has better advice. Anyone ever seen anything like this before?

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Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System

stuplich@ymail.com
Posts: 918
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Re: Electric Element in Water Heater Running Wild

Post by stuplich@ymail.com »

Don
From your description methinks that the HI-LIMIT/T'STAT failed in the closed position.
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HI-LIMIT/T'STAT

OR that the water remaining in the water heater, (after draining the via the open low point drains), still covered the ELECTRIC ELEMENT... but no longer reached the level of the HI-LIMIT/T'STAT.
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Mel
'96 Sahara 3530, mine since '01
250 hp 3126 Cat, MD3060 Allison

Moonwink
Posts: 14
Joined: Sun Oct 27, 2019 7:46 pm
Location: Near St Louis, MO

Re: Electric Element in Water Heater Running Wild

Post by Moonwink »

Mel, thanks for your response. The wiring for my WH is like the diagram I included in my post. I wish the 120v power went through a T-stat and ECO limit but my relay connects power straight to the element and relay coil gets its power from the control board. Neither of the switches over the door were turned on and the water heater was hotter than I've ever seen it - top to bottom I could feel the heat radiating from it. I pulled out the relief valve yesterday and see it's shot - pulling up the lever can't raise the stopper off the seat anymore. So I put a new one on order along with a new thermostat and ECO kit. With those parts and the element and relay - all that's left is the control board. The thing that puzzles me is why there was power to the element when there shouldn't have been. The contacts in the relay tested open on the bench but had to have been closed for any power to get to the element - see the wiring diagram in my post. I figure I had two problems. One, the bad connector on the black wire at the element caused 2 inches of the insulation to melt back and turned the copper black. The heat also melted the plastic around the screw on the element. I'm thinking the reason the water heater was running wild had to be a signal from control board to the relay when it shouldn't have. I think I"ll order a Dinosaur Electronics UIB64 board through Amazon ($108) to finish replacing all the controls involved with the electric side. If I hadn't gone back out to drain the tank when I did, I might have lost the MH and the house so I'd rather error on the safe side.
Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System

Moonwink
Posts: 14
Joined: Sun Oct 27, 2019 7:46 pm
Location: Near St Louis, MO

Re: Electric Element in Water Heater Running Wild

Post by Moonwink »

I managed to get the relay apart without destroying it and found the contacts had overheated and melted some of the plastic. Here's a close-up of the contact points:
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The contact points look like they're pitted and may have welded themselves together. The must have separated a little bit by the time I put my meter across the connectors but they weren't separated by much. The connector that caused the wire to burn was screwed to the heating element. The end on this relay shows no signs of damage.

It's a pretty cheap little relay to be as critical as it is.
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I haven't figured out how to mount a thermostat/ECO to the back of the water heater but I'd feel a lot safer with a safety device in the power going to the heating element.
Last edited by Moonwink on Tue May 12, 2020 2:37 pm, edited 1 time in total.
Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System

Moonwink
Posts: 14
Joined: Sun Oct 27, 2019 7:46 pm
Location: Near St Louis, MO

Re: Electric Element in Water Heater Running Wild

Post by Moonwink »

I wish the amp ratings were higher but I've ordered a second Thermostat/ECO limit kit to paste on the back side and run the 120v power to the element through. They're rated at 15 amps and the element is a pure resistive load (no surges) so they should work. I'll used insulated connectors on the wires and cover the area with some sort of shield. I might end up replacing the 20 amp Atwood relay with a 30 amp headlight relay so the contacts should last longer.

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Thoughts?
Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System

Safaritoonces
Posts: 127
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Re: Electric Element in Water Heater Running Wild

Post by Safaritoonces »

The circuit was designed for 20 amps, this cannot be changed to 30 amps safely, you will have a fire hazard. Something else imaybe wrong if the circuit is drawing more than the rated amps and must be found. The system worked for years and if it now does not, I would advise against bypassing the problem.

This is a resistive load, if the new heating element is good, measure the resistance of the original and new. If they are the same there's a problem elsewhere- You may have a short to ground in the power feed on that circuit. Possibly a screw thru the installation of a wire or the insulation rubbed off. Use a meter to measure the resistance to ground with the wire disconnected and so on. Something is drawing the extra current.

If you can a clamp on current meter, measure the working amps. If it's 80% or less of the breaker rating you don't have a problem. The system may have failed due to age. As the contact points pit over time they cause faster pitting in the remaining surface area until they fuse. You may no longer have a problem. The only way to really know is to measure the current.
Robert and Bev Lewis
2000 Safari Continental, since 2017
3126B Cat, 330hp
MD3060 Allison
Bowen Island, BC

https://safaritoonces.org/

Moonwink
Posts: 14
Joined: Sun Oct 27, 2019 7:46 pm
Location: Near St Louis, MO

Re: Electric Element in Water Heater Running Wild

Post by Moonwink »

Thanks for your reply Robert,
Both the old and new elements are 1400 watts. I'm not looking to drawing more power through the circuit. The problem must have been with the original OEM relay. The contacts were pitted and mush have welded themselves when I closed the door and went in the house for supper. Because Atwood doesn't have any safety device in the power to the element, there was nothing to stop the water heater from overheating. I thought about using a relay with 50% more capacity than the OEM relay to add a little cushion. Putting the limits in the power going to the element would mean that even if the malfunctioned in the future, power would be interrupted to the heating element and prevent the water heater from overheating. I feel this circuit needs a safety device in it. I replaced the original picture of the old relay with one alongside a dime to show it's size.

If you follow the "115v hot" black wire in the diagram I included in my first post. the relay contacts are the only thing controlling power to the element. If it was a 20 amp contactor like the ones in air conditioning units controlling the compressor, I'd feel more comfortable (I realize that's an inductive load but it's still carries a 20 amp rating).
Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System

Safaritoonces
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Joined: Sat Nov 02, 2019 9:51 am
Location: Bowen Island, BC
Contact:

Re: Electric Element in Water Heater Running Wild

Post by Safaritoonces »

If you are looking for a safety disconnect based on temperature there is another way. You can use a temperature controller called a loop controller. You mount the sensor on the tank, a proper epoxy would work, then you can control the opening of the relay for Power to the water heater based on a setpoint. I think the controller was about $20. If you look thru my signature link and go to the project menu for the Inverter upgrade all the information is there. The project video describes how the controller works. I use the controller to turn on a 120V fan when the temperature rises above the setpoint, there is a numeric display showing the temperature that the probe senses. It is very simple to connect. These are often used to control heaters for people making beer. The controller has internal relays and may have a high enough amp rating to work without a external relay. There are a lot of variations, you have to carefully read the specs.
Robert and Bev Lewis
2000 Safari Continental, since 2017
3126B Cat, 330hp
MD3060 Allison
Bowen Island, BC

https://safaritoonces.org/

TDJohn
Posts: 87
Joined: Sun Oct 27, 2019 11:34 pm

Re: Electric Element in Water Heater Running Wild

Post by TDJohn »

One simple and easy way to make sure the heater is off when you want it to be off, is to install a house hold heavy duty light switch some where between the circuit breaker and the water heater. My coach is setup like that, simple and no issues.

BTW, if you connection on the overheated wire was not loose, it is likely that the heating element partially shorted out, causing more draw than the wire could handle. What Mel mentioned of the water heater partially draining and not allowing the temp sensor to shut the heater down, sounds very plausible.
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.

Moonwink
Posts: 14
Joined: Sun Oct 27, 2019 7:46 pm
Location: Near St Louis, MO

Re: Electric Element in Water Heater Running Wild

Post by Moonwink »

My disconnect for the water heater is a 115v plug at the end of the HD extension cord coming from the cover over the heating element. The receptacle is a single outlet and the only thing on a 20 amp breaker. And yes, this is the way Monaco put it together. I've been researching the options mentioned by everyone. The contacts in the Elitech-STC-1000-controller that was recommended aren't rated near heavy enough to carry the heating element meaning I'd need to add another relay.
The Kilxon thermostat and ECO are rated for 15amps each. The 1400w element would draw 11.7 amp at 120v and I might be able to get by using one of them. I've got the bottom thermostat from an electric water heater that had a 4500w 240v (18.8 amps) element that should work if I can figure out a way to stick it to the tank. The label on J-B Weld says it's good for up to 550 degrees F. That should work. The highest setting is 150 degrees F. The original thermostat is fixed at 140 degrees and the ECO is set at 160 degrees. I'd never want anything over 140 degrees and if it got over that, there would be something wrong (like the contacts in that cheap little relay welded together again). The control I'd add would break the 120v power wire to the heating element preventing the element from running wild. I think that's the way I'll go.
I wonder how many water heaters they made like this? Can't believe Atwood thinks this design is safe.
Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System

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