My daughter's family has a Jayco TT with an Atwood 6 gallon propane water heater. It has not worked properly since they purchased the trailer new about a year ago. They have had it back to the dealer 3 times without satisfaction (another story).This unit has electronic (spark) ignition. After studying the diagrams I think I know what the problem is, but getting the correct part might be hard. Both the Emergency Cut OFF (ECO) and electronic water temperature switches (equivalent to the old fashioned mechanical thermocouple) have to be on for the burner to ignite. I don't think this is happening. The replacement pair from Atwood look a like and are not marked, so I assume they are identical.I would like an ECO switch that is ON until the temperature is ABOVE 170F. If my understanding of the circuit operation is correct, the gas valve will stay closed until the water temperature switch calls for ignition and the gas valves to be open.Does anyone know where I can buy a high temp ECO shut off switch that would work withe the Atwood water heater ?

Let me ask a couple questions.Use an Ohm meter and measure the ECO and thermostat. Disconnect one of the brown wires. Measure for resistance between the contact and the other brown wire. Should read a direct short. Reconnect wire when done.Next disconnect one red wire and test(ECO). Should read direct short.Next adjacent to the ECO/thermostat is a piece of heat shrink tubing on the wire. Inside is a thermal fuse. Test it for continuity.Amazon is your friend!Amazon

Atwood t-stat (normal temp) controls the on/off firing of propane. It closes when water temp drops to 110*F allowing 12V DC to go thru ECO and to gas valve. It OPENS to shut down propane firing at 140*FThe ECO t-stat (Energy Cut Off) is always CLOSED unless normal t-stat fails to OPEN and water temp goes HIGH.It OPENS at 180*F shutting down propane firing and triggering the 'FAULT LIGHT'IF ECO OPENS it will self reset when water temp drops below 150*F but 'Fault Light' can not be reset until switch is turned OFF then back ON.Thermal Fuse (Clear tubing) connected to t-stat is a 'one time temp fuse'. IF it blows it has to be replaced. When it blows ALL 12V DC power is lost.....nothing will work until replaced.It is a safety device that burns out at 190*F .....it is for flame blow-back out of combustion chamber/burner tube.ECO and T-stat are both just snap disc devices BUT the terminal/spade connectors are different sizes. ECO larger. So the brown wires only fit the T-stat and the Red wires only fit on the ECOECO and T-stat connections need to be clean and tightECO and T-stat must be held tight against tank wall12V DC goes to ECO and then to gas valve solenoids at same time High Voltage DC goes to spark electrode....DC will only remain on gas valve solenoids for 6-8 seconds unless main flame lights off and proves it lit via milivolt signal back to circuit board.Normal T-stat (small terminals).......Opens at 140*F (controls firing and water temp between 110*F to 140*F)ECO T-stat (larger terminals)..........Opens at 180*F (always closed unless temp goes too high)Thermal Fuse (small terminals)........Burns out at 190*F (No DC for anything if it blows)

There is a nice troubleshooting info at "beamalarm.com

Old-Biscuit wrote:ECO and T-stat are both just snap disc devices BUT the terminal/spade connectors are different sizes. ECO larger. So the brown wires only fit the T-stat and the Red wires only fit on the ECO.I won't have access to the TT for another week, but I don't recall that. One of the replacements had a round terminal soldered to the one of the terminals.Old-Biscuit wrote:Normal T-stat (small terminals).......Opens at 140*F (controls firing and water temp between 110*F to 140*F)ECO T-stat (larger terminals)..........Opens at 180*F (always closed unless temp goes too high)Thermal Fuse (small terminals)........Burns out at 190*F (No DC for anything if it blows)Good to know, but not exactly easy to test. I will have to get the tea kettle out !

The thermostat with the round wire terminal soldered to it is for the 16 gallon EXT water heater and is set for about 155 degrees. This is the wrong thermostat for a 6 gallon unit. You mentioned a kit that contained two identical looking thermostats. This is the kit you need. If you look at the back of the thermostats, one will say 60C and one will say 82C. The 82C is the ECO.

Atwood water heater ECO and temperature thermostat

Old-Biscuit
Explorer III
Oct 23, 2016
OK.....

ECO opening is a real long shot.
If it was opening early it would continue to do so.

2 nights of use and 1 non-relight.
That could be spark electrode position....has to be directly in flame (tip should get RED) and gap set at 1/8"
That could be ground issue.......either at spark electrode assembly (bracket/mount screw not tight/clean contact)
That could be loose spade/terminal contact on t-stat/ECO
That could be connector contact issue at circuit board
That could be gas solenoid terminal/spade contact issue
That could be a fluke

Poor or corroded wire connections cause most of the intermittent problems in water heaters.

And no grease or dielectric sprays etc.
T-stat and ECO must make clean constant direct contact with tank wall.
Terminals on the t-stat/ECO should not move and wire spade connectors should go on the terminals tight.

1 non-fire is not a real issue.....if it continues to not fire up --- that is an issue
jetcare
Explorer
Oct 23, 2016
I don't think I have ever found a bad ECO. I do see the thermal fuse breaking down causing intermittent operation. If I have intermittent operation, I change the thermostat and ECO kit and the thermal fuse.
theoldwizard1
Explorer II
Oct 24, 2016
Old-Biscuit wrote:

That could be spark electrode position....has to be directly in flame (tip should get RED) and gap set at 1/8"

Definitely RED and they paid $70 to have the service center "adjust" the position.

All wires and connectors are NEW and appear to be clean. The Temp and ECO connectors have been cycled several times now. It wouldn't hurt if I removed and re-seated the circuit board connector.

Let's hope that one time was a fluke !
theoldwizard1
Explorer II
Jun 21, 2017
Well, my daughter's family just got back from a 5 day trip. Water heater was non-functional most of the trip.

They are talking about going to an instant water heater, but none of the residential gas models will fit and the electric ones require 240V (they have a 30A connection).

They are concerned about their HOA so they don't want to keep it overnight so I can do more diagnosis.

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