Atwood Propane Water Heater won't light

[Healeyman]

My wife "thinks/but not sure" that she left the water heater on all day.

She shut it off in the evening, but it won't light the next morning.

I tried, but failed, to light it manually. Seems as if there is no 12V power to energize the spark lighter or open the gas valve.

I suspect that the thermostat or Emergency Cut-Off is open.

When it warms up a bit, I'll troubleshoot with my meter.

Any other places to look?

Thanks,

Tim

[tap4154]

How old is it? Mine is 10 years and recently began lighting, then quickly defaulting. Turned out the igniter/flame sensor assembly was shot. Got a new one from Amazon for $14 and it\s working great now.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Persistent]

Fuses are the easiest things to find and fix. Fuses blow for a reason and replacing may be futile, but it is easy to do.

12 volt control boards and temperature sensors are frequent causes of failure of main valve to open. Igniters fail with use and age, but also fail when control boards don't provide power to them.

Old Biscuit knows them inside and out. Post your heater make and model and he will have a good chance of predicting the cause.

[Qwert66]

First thing I would check is for 12+ VDC from the batteries.
Second thing is does the propane stove stay lit.
Second thing would be does the water heater heat on the 120vac option.
Easy things first.........
Then because it is an Atwood, are the 2 ground wires making good contact to the threaded post on the aluminum tank (located on the back of the tank just above the electric heating element)

Wishing you the best. Leaving it on continuously vs turning it on and off when desired should not effect its operation beyond the time it takes to heat the water and the amount of energy it uses.

A temporary jumper wire across the over temp/thermostat may tell you something if you feel comfortable with that approach.

[Old-Biscuit]

Voltmeter and follow the DC Circuits


Following based on your 'Propane Water Heater'----which I take as GAS Only Model

***If Gas/Electric slightly different circuit but DC+ for Propane Side still applies



DC+ from battery to on/off switch
DC+ from on/off switch to T-Stat, thru the Termal Fuse to circuit board (BROWN wires) (T-stat opens when temp reaches 140*F/CLOSES at 110*F)

Spark electrode should be 'firing' then
DC+ from circuit board to ECO to Gas Valve Solenoid (RED wires)
With in 6-8 seconds of gas valve opening flame should light off and PROVE it lit.
Flame generates a milliamp current that circuit board is looking for---no signal/DC gets dropped to Gas Valve (RED Wires)
**Spark Electrode is used as pathway for flame proving signal so tip needs to be clean, wire intact in ceramic insulator, no cracks in ceramic insulator, high tension wire connection at transformer on circuit board clean/tight AND spark electrode assembly mounting screw clean/tight connection (ground)


SO have to have DC+ to circuit board via Brown Wires before DC+ can be sent to SPark Electrode/Gas Valve via Red Wires
T-stat connections/contacts clean/tight
Thermal Fuse (Clear tubing) connections clean/tight and fuse good (Blows at 190*F and has to be replaced)

**Can remove from circuit and connect brown wire from circuit board to t-stat to test if Thermal Fuse is bad---replace ASAP---safety device/blow back of flame from combustion chamber/burner tube!


ECO connections/contacts clean/tight----ECO Opens at 180*F and will trigger the FAULT Light (also triggered by NO FLAME)
Gas Valv e Solenoids ...clean tight connections (Red DC+ and Black Ground)
Solenoids resistance test........S/B 48 ohms each


So follow the DC.......

[Healeyman]

Originally Posted by Old-Biscuit

Thermal Fuse (Clear tubing) connections clean/tight and fuse good (Blows at 190*F and has to be replaced)

**Can remove from circuit and connect brown wire from circuit board to t-stat to test if Thermal Fuse is bad---replace ASAP---safety device/blow back of flame from combustion chamber/burner tube!

Mr. Biscuit,

My Thermal Fuse is located, in series with 12V+) on the right terminal of the T-Stat thermal switch.

There is NO continuity through the T-Fuse. It is a G4A00 - Bright GREEN glass seal. The component is marked 098C (=208F).

Although Amazon and Ebay have a LOT of T-Fuses available, I cannot find a good source for an exact 098C replacement. Since it is used for flame blowback mitigation, might I use one that is close in temperature.

Thanks for your help.

Tim

[Old-Biscuit]

Atwood says they open when exposed to temps above 190*F......Atwood OEM comes 2 to the pack for $16/$23 ........


They are nothing 'special' just heat sensitive so get close to 190*F
Plus the spade connectors are 'small'

[Ray,IN]

Listen to old-biscuit! He advised me correctly last summer. I bought new parts from Amazon for less than half the cost at the local RV parts store.

[Healeyman]

Originally Posted by Old-Biscuit

They are nothing 'special' just heat sensitive so get close to 190*F

UPDATE

The problem was indeed the thermal fuse that resides just outside of the combustion chamber.

The "old" thermal fuse had no continuity. Its melt temperature was 98C (208F).

I bought a 10 pack of 99C (210F) on Amazon for $9. They were delivered tonight.

The new 10 ALL have continuity. The fix goes in tomorrow.

AMAZON wins again. Old-Biscuit wins again!

Tim

[Healeyman]

Moderator,

Please remove the incorrect link to Amazon that is shown in Post #9.

Thanks,

Tim

[Solo_RV_Guy]

Originally Posted by Healeyman

Moderator,

Please remove the incorrect link to Amazon that is shown in Post #9.

Thanks,

Tim

Hi Tim-

I notified mods to check your post for you. To help in the future:

Each post has a little triangle symbol (to the left, under the poster's name and other info). Click on it to bring up a message window that will contact a moderator when you're done.

You can report your own post to request additional edits or other changes; you can report non-compliant posts from other users (things that obviously or likely violate the "community rules").

Good luck and save travels!