Suburban Water Heater Only Ignites on Shore Power

[Wakesupremo]

Sorry, me again. I have been madly getting my 1989 Sunsport ready for my first race weekend this year. I have tried all of the appliances and have realised that, the suburban water heater will only ignite while on mains power. Is this normal? Surely it should ignite with 12 volts?? The switch on the end of the sink unit will only light up when theres mains power. Where is the 12 volt power taken from? I have no blown fuses unless theres a fuse on the actual unit somewhere.

 

[Chuck v]

The water heater will make hot water when on mains power without using any gas or 'lighting' as its heat source is the electric element. Are you sure the propane is ever actually lit in the suburban heater?? Let us know what you find...

Chuck

 

[Wakesupremo]

Hi again Chuck. It ignites on gas but will only do that while it is plugged in to the mains. The illuminated switch on the end of the kitchen unit will not illuminate unless its plugged in to the mains. I don't know if it even has an electric element!!But, if its not plugged into 'shore power' it does nothing.
I'm guessing that it is a suburban 6 gallon unit because the outside access door was missing and when I researched for another door ,that looked the most likely to fit and it fitted exactly.

 

[Chuck v]

Wake,

Some Suburban 6 gal WH are both AC plus propane, others are propane only. To my knowledge, there were NONE that were AC only... If your coach has a lighted toggle switch that looks like a normal residential wall switch -- it is the AC for the water heater. You can always turn your propane tank main valve off such that the stove top does not light, and verify that you still get hot water being produced by the AC heating element in the Suburban.

Most of the combined AC/propane heaters look like this at teh front of the unit behi8nd the exterior door:

You can view the manual covering a range of these heaters here:

https://myrvworks.com/wp-content/uploads/2020/04/Suburban-Water-Heater-Service-Manual.pdf

Chuck

 

[Wakesupremo]

Thanks once again Chuck. A massive help.

 

[Wakesupremo]

I have printed off the whole manual Thanks Chuck but, I still can't see any reason why mine is doing as it does. I don't think mine has a 120 volt element, I think its gas only, however, today I have turned it on, as said before, Ive had to have the shore power on. It lit as it should with no problem, I turned off the shore power and it turned off as well. I can't see anything in the manual that remotely explains this.

 

[Chuck v]

I know that from your earlier posts here on other parts of your coach that the harness and wiring have been hacked some by a prior owner or two...maybe the heater is another victim. The manual should specify how it SHOULD be wired -- but I would not expect the manual to anticipate all possible hacked outcomes.

Please post a picture of the controls on you heater near the burner...it may be evident if there is an AC option on it...

 

[Wakesupremo]

Thanks again Chuck. I don't think there are any controls at the burner apart from a gas solenoid.

 

[Wakesupremo]

If I went to it right now and switched the coach battery on and then the water heater switch at the end of the sink unit, The red light will illuminate for a few seconds on the switch. From reading the manual that means 'no LPG present'. If I then switch on the shore power supply, It will go click click and ignite. If I then turn off shore power the flame goes out and it doesn't try to ignite. If, however, I keep shore power on it will stay alight.

 

[Chuck v]

Most heaters have two push button resets under a rubber boot, and a "secondary" toggle switch for the AC element...

The rubber boot covers two momentary resets for circuit breakers, the left on being the AC controls and the right one being the Propane controls, I believe...

Your heater appears to be a much older unit.

 

[Wakesupremo]

Im fairly certain that mine doesn't have those.

 

[wildtoad]

Sounds to me like the ancient wh is gas only, and there is a wiring or battery issue. Seems to work when 110v is available, not so when running on battery. When not hooked to shore power or generator (if you have one), what is the voltage on the coach batteries? You say if using coach batteries, the red light will glow, but not start. But on 110v it works fine. If you have a gen, does it work the same? Just guessing but perhaps there is insufficient power to open the gas valves and fire the igniters when on just battery.

 

[Wakesupremo]

Thanks Wildtoad. There are 2 big leisure batteries which are connected to solar panels on the roof and constantly sit at 13.2 volts. From my understanding, the red light comes on when its not ignited. I'm really confused with it. Ive got to go through it all and see exactly whats what but, being tucked right under the sink and behind the drawers it isn't easy to get to.

 

[wildtoad]

Yeah, they don’t make it easy for the DIY folk.

The light does say an ignition problem, no gas being the primary.

Hope you find the cause.

 

[Wakesupremo]

Thank you again. A friend that was over earlier did mention that, when the battery charger is on, it creates a different circuit as the batteries can't be both charged and used at the same time. There must be a changeover relay in that circuit so, it might be possible that its only getting power when the battery charger is on. Thats tomorrows job now!!!

 

[Chuck v]

Lead acid batteries CAN be charged and used at the same time -- this is how all automobile systems work of course. I can't imagine what your friend is talking about...unless there is some voltage conversion going on as might be the case with a 24 volt lithium system and a converter to operate 12 volt RV loads. But even for that possibility, there seem to be systems that work (discharge into a load) and charge simultaneously.

Can you explain what might be the issue your friend was addressing. We are talking about the shore power system charging of the house batteries, correct?

Chuck

 

[Wakesupremo]

Hi again Chuck. We have come to the conclusion that its not a case of the shore power having to be on. Its more that the battery charger has to be on. ( powered via the shore power).Is there a possibility that the switch for the water heater has 2 supplys? one from the 12 volt distribution board and another from the battery charger. So that, if the 12 volt circuitry, for any reason, cant work it, the battery charger circuit would.

 

[Chuck v]

Definitely a high probability of a wiring hack/error considering the history of your coach prior to your ownership...!! Start at the heater itself and trace back with a voltmeter for the conditions where it works and those where it does not -- surely you will find a reason.