Water Heater will not start

[AccessMaster]

Over that last year or two on occasion the hot water switch would have to be recycled to get started. Recently it became almost every day. Now it no longer will start. The light control switch indicates that it has been turned on but that it has failed to ignite. The electric element quit years ago. It has been running on propane just fine until now. It is in a Travel Supreme motor home.
Visually the unit looks OK. What are the trouble shooting steps I can go thru? I know how to use a multimeter.

[aether_one]

Is it trying to light? Can you hear it sparking?

Is the gas valve opening (solenoid clicking)?

Several things to investigate before you need the voltmeter.

[Old-Biscuit]

Brand/Model would be very helpful


Providing some answers will be also
Does it SPARK (CLICK, CLICK, CLICK)?
Does Gas Valve clunk (solenoids energizing) even of it doesn't spark?


NO
Then you need to start back at On/Off Switch and verify (multimeter) that you have 12VDC TO the Switch and FROM the Switch


NO....then Locate/ID which main supply fuse it bad....DC Dist Panel
YES...then need to check for DC to t-stats


But w/o Brand/Model that is where they differ.


Year of RV could matter also





So POST Back.

[AccessMaster]

Update. It would not start for a good hour or more earlier today. It just started and is heating as it should. What could be causing this behavior. The unit has not moved. Nothing has changed. The unit is currently inside in storage not subject to any outside influence. It is plugged into shore power.

[AccessMaster]

2002 Travel Supreme. I cannot determine the model of the water heater but it is still the original. Guess I should be glad it works at all, but hey if not broke ...

[Old-Biscuit]

Go thru each connection and make sure they are CLEAN & TIGHT

[rarebear.nm]

Can you at least provide a couple of pictures of the heater?

Does it have a plastic drain plug or an anode rod at the bottom?

There's only a limited number of electrical parts to these systems. If it just came on without doing anything, I'd start to suspect a sticky switch or solenoid valve. It could be something else equally well, like a T-stat or control board.

To help you we need more information.

[baraff]

Usually it's the flame sensor or igniter. Sometimes the porcelain insulator develops a hairline crack which can cause the spark to short. A classic symptom is sometimes it works, and sometimes it doesn't. This happened to me at about the 10 year mark. A new flame sensor solved the issue. I always carry a spare now.

Another issue could be dirty or corroded connections, easy to check.

[AccessMaster]

Maybe this picture will help. What / where is the flame sensor?

[AccessMaster]

The picture is upside down. The anode rod is at the top. The insulator was pushed back to expose the electrode.

[Ljwt330]

Suburban water heater. Metal drain plug (with anode), burner vent on the upper right (with picture correctly oriented), electric heating element under a cover behind the burner tube.


All recommended remedies apply.

[Alpine36]

Yes, that's an Suburban gas/electric model.
Consider this a good time for a little preventative maintenance.
Purchase a new anode (or three) and electric heating element.
Give the tank a good flush out, replace the heating element and anode.
Fill the tank and test heating element operation. Typically you need to turn on the outside rocker switch at HWH, and turn on a breaker on main panel. Not sure about the intermittent gas operation but that's where I'd start.

[Old-Biscuit]

OK so now it has been ID .....Suburban


Above the gas valve under the 'Pus to Reset' cover is the dual set of t-stats
120V electric is on Left side---Black Wires
12VDC propane is on Right side---Red Wires
Hi temp t-stat is at top and has a push button manual reset




Electric Element

120VAC comes from Main Panel Circuit Breaker ------- AC Junction Box (backside of tank) to OEM ON/OFF Switch in lower left corner of outside compartment
120VAC then goes from AC Junction Box to OEM switch then to the set of t-stats and then to element
Common issues.....
*Bad On/Off Switch
*Bad wire nuts in junction box

*Tripped Hi t-stat
*Melted wire between Hi/Normal T-stat
*Chaffed wire at t-stats
*Burnt out/shorted element






Propane System

12VDC comes from a FUSED source to the On/Off Switch
12VDC goes from switch to DC Junction (backside of tank) then to set of t-stats----from t-stats to Circuit Board (backside of tank)
Circuit Board then sends 12VDC to SPARK electrode and Gas Valve at same time. SPARK ignites gas....flame heats water
Common Issues---
*Blown supply FUSE
*Bad wire nuts in junction box
*Tripped Hi T-stat
*Melted wire between Hi/Normal T-stats
*Chaffed wiring at t-stat
*Circuit Board wire connection
*Spark Electrode-----bad wire, cracked ceramic, bad ground
*Gas Valve solenoids.....BOTH have to work to Open Gas Valve







Got a Voltmeter?
Follow the Voltage-----AC or DC
Find where it is and then ID where it is NOT


Water in tank needs to be below 100*F in order for T-stat to Close (if Open no DC past t-stats)
Normal opens at 130*F
Hi Temp trips at 170*F/180*F (vintage depentent)

[baraff]

Originally Posted by AccessMaster

Maybe this picture will help. What / where is the flame sensor?
Attachment 271887

It is actually with the spark electrode. See Old Biscuit's schematic post above. On the schematic look for the electrode. Note the two probes, one is the sparker and the other is the flame sensor. Inspect the porcelain insulator. Actually I would just replace it because if it is original I can almost bet that's your issue.
I highly suspect it is the electrode because it works intermittently. That said, check and clean all electrical connections first.

You should be able to find a replacement on Amazon if you put make and model into the search. They are not expensive. (at least mine wasn't, but I have an Atwood).