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Kind of random; but troubleshooting on an RV water heater?  RSS feed

 
Jen Fan
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I had no idea where to put this, hopefully I'm not too far off!
Instead of going through the bother of making new forum accounts on random RV forums and such (which I've DONE and received no input or help) I figured I might just be able to ask here, as I imagine many of my fellow permies have lived in RVs!

I live in my 5th wheel.  My water heater began lighting intermittently last winter.  Turn it off and back on enough times and it would eventually kick on.  Sometimes I'd have to let it sit a few days then try again.  Not convenient, but we got through it.  And also too much below zero to want to work outside when I could just boil water instead :P  The water heater worked stellar all spring, magically, and was good through the end of July.  Then it stopped working again.  It kicked on ONCE in early August for about 5 min then stopped working again.  Haven't been able to get it lit since.  Back to boiling!

I know, I know, I've been on google trying to trouble shoot but I get sick of going through one dozen, two dozen, three dozen sites and not finding what I need.  This is new to me and I'm not familiar with the parts yet.  Bah!

Basically, as far as I can tell, I'm not getting any propane to the unit.  I smell no propane while it's 'trying' to light.  It tries to spark but no flame lights.  It will always try to light 3 times before it gives up, so I have time to go outside and observe what's happening. 
Yes, I have propane hooked up.  No there's no leak in the line.  I cleaned out the tube (the gas burner tube I believe?) and it didn't seem clogged or particularly filthy.

The RV is an '06 Nash, built pretty solid, no other issues.

THANK YOU IN ADVANCE, I miss my hot water :B
 
Denise Kersting
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Is there a shutoff valve between the tank and the heater? (I know, sounds silly, but sometimes easy wins) If there is propane in the tank, the valve has been cleaned, and there is spark, you should be good to go. The only other thing I can think of is if the thermostat for the tank is blown (or dialed down too low), it isn't calling for heat when it should.
 
Jen Fan
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Denise Kersting wrote:Is there a shutoff valve between the tank and the heater? (I know, sounds silly, but sometimes easy wins) If there is propane in the tank, the valve has been cleaned, and there is spark, you should be good to go. The only other thing I can think of is if the thermostat for the tank is blown (or dialed down too low), it isn't calling for heat when it should.


Hm...  No shut off valve that I'm aware of.  It is quite odd, yes.  The intermittent climax of the issue says more of 'something's gotten clogged' to me.  But I don't know what!
I don't think it's a thermostat issue; if the thermostat was blown and not calling for heat, it wouldn't bother trying to light.  Unless I'm mistaken?  I've only dealt with (and built) electric water heaters before, my logic stems from that experience.

My next step was going to be replace thermocouple and see what happened...
 
Denise Kersting
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First is this a piezzo ignition water heater (ie no pilot light?) Ok, is anything else hooked up to the propane? If so, are those working correctly? If there isn't anything else, (or they are they are acting up too) then I'd go after the pressure regulator on the propane tank. You can try to reset a propane tank reg., but to reset you have to disconnect the propane line (and open the demand side to any appliance). You are trying to remove any pressure differentials on any side so the check valve resets. Then reconnect and see what happens...(don't bother with this if you have another propane appliance working fine off the system). Edited to state that if you do open the system to air, then it will take several attempts to relight as air will be in the line and not gas. If you have a stove connected it's easiest to bleed the air out of that first and then try other appliances.
Also, you are right that it wouldn't light if the thermostat wasn't calling for heat; I was thinking thermocouple. The thermocouple is a common failure part, and even if the tank did light, if the thermocouple wasn't working it will shut the tank down. Can you view if the tank actually "lights" or not, even if momentarily? If it lights and then shuts off it is probably the thermocouple, which is a cheap part to replace.
 
Jen Fan
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Denise Kersting wrote:First is this a piezzo ignition water heater (ie no pilot light?) Ok, is anything else hooked up to the propane? If so, are those working correctly? If there isn't anything else, (or they are they are acting up too) then I'd go after the pressure regulator on the propane tank. You can try to reset a propane tank reg., but to reset you have to disconnect the propane line (and open the demand side to any appliance). You are trying to remove any pressure differentials on any side so the check valve resets. Then reconnect and see what happens...(don't bother with this if you have another propane appliance working fine off the system). Edited to state that if you do open the system to air, then it will take several attempts to relight as air will be in the line and not gas. If you have a stove connected it's easiest to bleed the air out of that first and then try other appliances.
Also, you are right that it wouldn't light if the thermostat wasn't calling for heat; I was thinking thermocouple. The thermocouple is a common failure part, and even if the tank did light, if the thermocouple wasn't working it will shut the tank down. Can you view if the tank actually "lights" or not, even if momentarily? If it lights and then shuts off it is probably the thermocouple, which is a cheap part to replace.



Hm.  I'm honestly unsure what type it is.  There is what I believe is the thermocouple coming in from the propane line, it outlets into a hooked tube about 12" long, and the spark occurs on the other end of that tube.  There is no continuous pilot light, it only ignites when needed.  Is that what you mean?  If so, then yes, probably a piezzo ignition.

Yes, heat and stove run off propane and work flawlessly.  I've got a new pressure regulator on the tank as of January 2017, it's working wonderfully.

No, there is no flame, it is absolutely not lighting.  There is no propane being released to the spark.

Thank you
 
bob day
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I was vaguely watching this thread and you got lots of good questions and answers, and with the history of running and then stopping and now stopping altogether sounds like it could be a thermocouple type flaw. Since I know next to nothing about electronic controls like this I can only imagine the traditional thermocouple control has been incorporated into an electronic valve,  of course all this is really just idle speculation.

The real key to this question lies in finding out make , model and serial number.  It will all be there somewhere.    Did you ever look for the name and model number, likely a schematic is available on line which could identify the possible other parts that might be involved.  Being able to search for the precise parts can probably save you money over calling the dealership which will likely add 100% to the actual cost of the part. You may even find a utube video showing you how to replace the part.

But it all starts with looking for and finding the name plate that has all that information on it. Even just the name on the water heater would be a start

Some heaters may have an access panel inside the rv, some maybe outside, or both. Usually it's just a couple screws holding a cover, check around where  the air filter is replaced.  expose the area where you looked for the pilot light  That nameplate should be fairly accessible wherever it might be. You shouldn't have to really meddle in the guts of the thing to find the information

It may be stamped into an inside cover, but usually it will be a little rectangle metal plate riveted somewhere covered by a piece of trim with a serial number, company name, model number, basic specs, btus, etc

Failing that, you may be able to identify the type of water heater from the year,make and model of the rv--or at least narrow it down to a few types instead of a few hundred. Then some quick visual comparisons may give you  the true identity of your heater.

But really, until you do that basic step everything will just be speculation.

 
bob day
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owners manual


The manual did not specify which water heater you might have, so if you got any literature with your rv, you can probably find the make at least in that.
 
Leeon Kirby
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Likely the regulator or the gas valve. Check pressure with a manometer at the valve. You should have 11" of Water Column for propane.
 
bob day
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The test for regulator and main gas valve would seem to be satisfied since all your other appliances are working off that same line. If you have traced the wh supply line back to the main gas line, there may be a manual shutoff valve  in that line which you could check for, although I think we were all assuming that you had not turned off any valves and at one point the unit was working  and slowly stopped functioning altogether on its own.

btw the thermocouple in a pilot gas water heater is a little probe that is kept hot by the pilot light and keeps the gas flowing.
what you described was likely the burner assembly

The thermocouple is likely over the end where you see the spark, where it would be at the top of the flame coming out of the burner assembly and should go into a heater control box somewhere between the gas main line and the burner assembly

Of course, like I said, without the model number this is still speculation. One thing I've learned is people are always trying to build better mousetraps, and there may be some other sensor taking the place of the thermocouple.

Or the thermocouple may have a different name, or?

I don't know if anyone has asked if there are any kinks in the gas supply line to the water heater, That seems unlikely, since usually those tubes are protected from random sorts of everyday injury but it is something you could check when looking for the model number
 
Denise Kersting
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If you can see a spark, it should not be the piezo ignitor.
If there is no flame, it's not the thermocouple, the thermocouple will cut off the gas if no flame is sensed after x-amount of time and then it will pause to vent unlit gas and try again and after its set amounts of re-lite attempts it will stop.
Since other appliances are running off the same supply, it is probably not the regulator.
It must be something in the supply side possibly the gas control valve for the burner. The gas control valve should automatically open and let the gas through when there is a call for heat, if it is malfunctioning, it may not allow the gas through to get to the spark. Have you attempted to light the gas (by the piezo where it would normally take off with flames) with a long match or a grill type lighter to reach it. There is a slim chance that the gas outlet and the igniter have become mis-aligned. If it lights, you will probably need to look at correcting a mis-alignment. Best guess is the automatic gas valve is stuck or broken, and fixing that would hopefully fix your issue.
 
Jen Fan
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Thanks for the replies.  I will search for some info on the model and I will also get a photo of it.

I cannot "see" a spark, but I can clearly hear/detect where the spark is coming from.

Yes, the water heater worked flawlessly for the first 4 months, then started acting up.  It stopped misbehaving on its own and worked great again for a couple more months before it stopped lighting all together.  Nope, never messed with any shut-off valves.  Also, taking it in to a shop is not an option, I'm living in it and have no way of hauling it at this moment. 

Hopefully I'll get the photo and info tonight!
 
Jen Fan
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Jen Fan
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Burra Maluca
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Some heaters need a battery to create a spark and will cease to work if the batteries go flat.
 
Jen Fan
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Burra Maluca wrote:Some heaters need a battery to create a spark and will cease to work if the batteries go flat.


Are you referring the the RV batteries or a battery on the unit itself?

I don't think it's a lack of spark issue.  It seems to be a lack of propane issue.  I should be able to smell a whiff of propane if I'm outside while it's igniting (I hate that smell, very sensitive to it).  I smell nothing when it's clicking/sparking, attempting to light, and nothing is igniting.
 
Walt Chase
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Most likely culprit with the direct spark ignition type water heaters is going to be something going on with your valve.  In the last pic you posted it is the weird box of a thing between where you circled where the gas comes out and the inlet LP line.  Something is not letting gas go through the valve to the burner.  Sensor??  I'm not totally sure how those type WH work, but something should, with a lack of a thermocouple, be telling the gas valve that the WH is calling for heat and letting the gas flow through the valve to the burner.  The ignitor should time itself out after three failed attempt to ignite the burner.  IF the ignitor is sparking then it is getting the info that the WH is calling for heat, but the gas valve isn't letting the gas through.  Faulty valve or an electrical problem. 

One other thought.  Is there any way that the supply line or burner nozzle is clogged?
 
Burra Maluca
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Jen Fan wrote:
Burra Maluca wrote:Some heaters need a battery to create a spark and will cease to work if the batteries go flat.


Are you referring the the RV batteries or a battery on the unit itself?


On the unit itself.  I only mention it because it's such a simple fix if this turns out to the case, if not for you then for anyone else reading this thread.
 
Jen Fan
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Walt Chase wrote:Most likely culprit with the direct spark ignition type water heaters is going to be something going on with your valve.  In the last pic you posted it is the weird box of a thing between where you circled where the gas comes out and the inlet LP line.  Something is not letting gas go through the valve to the burner.  Sensor??  I'm not totally sure how those type WH work, but something should, with a lack of a thermocouple, be telling the gas valve that the WH is calling for heat and letting the gas flow through the valve to the burner.  The ignitor should time itself out after three failed attempt to ignite the burner.  IF the ignitor is sparking then it is getting the info that the WH is calling for heat, but the gas valve isn't letting the gas through.  Faulty valve or an electrical problem. 

One other thought.  Is there any way that the supply line or burner nozzle is clogged?


I figured propane should be coming out of the circled spot ('nothing coming out').  But none is. 

So does anyone know what this kind of WH is called?  Still struggling to find a schematic or diagram to lend a hand. 

Something like a sensor is a possibility for sure.  Like I said, it sparks for a few seconds, rests for 10-15 seconds, then tries sparking again.  It will do this three times and then give up.  I smell absolutely no gas, I'm certain no gas is getting to the unit.

The only other thing I can think of is a clog.  A very tiny spider?  I don't know how to clean this little pipe out!  The opening is very tiny.  I didn't want to disassemble anything unless I knew what I was doing  
 
Jen Fan
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I did find a bit of literature!  Woohoo!  Thank you JustAnswer.com and following random links!  :P

And I just learned that this unit is dual LP and electric.

From what I'm reading, the ONLY cause for these symptoms would be poor propane pressure.  I'm starting to think my dilemma may be as simple as s tiny little spider dead in that little tube.  That's the only explanation for no gas coming out since it's coming directly off the propane lines.

I will experiment with the electric side of the unit and likewise try finding a way to clean out the culprit tube (still don't know what it's called!)
 
chad Christopher
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No gas is more than likely the gas pressure regulator solenoid. The thingy above  the "no gas" circle. Most units are unserviceable. Another option is that there are tiny heat sensing buttons much like the top of a canning jar lid. That pop when overheated. But fluctuations in moisture and temp can temporarily cause the sensor to contract, if not triggered from extreme heat. Both pretty cheap fixes. Since I can't dig around, you have to do the research and look for yourself. The capillary fuel tube, is a possibility. But unlikely. Since it's dual fuel. The jet port that expands the gas pre burner, could be clogged up with the high carbon content that most propanes carry
 
Jen Fan
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chad Christopher wrote:No gas is more than likely the gas pressure regulator solenoid. The thingy above  the "no gas" circle. Most units are unserviceable. Another option is that there are tiny heat sensing buttons much like the top of a canning jar lid. That pop when overheated. But fluctuations in moisture and temp can temporarily cause the sensor to contract, if not triggered from extreme heat. Both pretty cheap fixes. Since I can't dig around, you have to do the research and look for yourself. The capillary fuel tube, is a possibility. But unlikely. Since it's dual fuel. The jet port that expands the gas pre burner, could be clogged up with the high carbon content that most propanes carry


Hm...!  Would you happen to be able to doodle on a photo of the unit and point out the parts you are referring to?  I've got the owners manual .PDF open but it's not terribly helpful.  There's nothing mentioned about no LP gas to unit outside of "check the tanks".   Anyways, I can try some diagnostics with a little more research, and knowing which thingamajigs are what would be very helpful!  Thank you
 
Walt Chase
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I think Chad and I are talking about the same "thingy" just using different terminology.  It would be what I called the weird box of a thing above your red circle that says gas comes out here.  It is the control box for the WH.  It is between where your LP comes from the tank and where your red circle is that says gas comes out here.  That is the "brains" of the system for lack of a better word.  They are not generally user servicable.  Most are user replaceable and I have replaced several over the years in different RV's. You might be able to replace the selonoids on the valve, but I am unfamiliar with your type WH.  Should be able to source one at just about any decent RV center with a repair shop or online.  Online may be less expensive.

It is also possible that the jet is completely clogged with carbon.  What I am talking about is the burner jet.  The silver pipe bent in a circle below your control valve that goes into the burner has a brass end.  You have it circled as "no gas comes out". That is the jet.  It has a TINY orifice and can get clogged.  You would have to remove it and clean it out.  I've used single strands of copper electrical wire with success before.  There are special little tools made for the job, but for the life of me I cannot remember their name.


ETA:  Found this and it might answer, or help answer your questions.  Someone else seems to have had a similar problem as you.  Link: https://www.justanswer.com/rv-motorhome/4n9vf-suburan-water-heater-sw10de-electric-propane.html
 
bob day
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Hi Jen, sorry I didn't get the notice of new posts.  But it looks like you have had lots of good advice.  I will second or third the idea of that gas control--or it could be the orifice (gas comes out here)

I have always been told not to fool around with these trying to clean the orifice with a wire since altering the dimensions of this tiny hole could be a safety issue. the orifice is probably replaceable, usually  fairly small roughly pea sized with a threaded end that simply unscrews from the tube-- a socket will usually fit over it to remove it from the end of the tube. At any rate that tube will end up coming out of the control unit more than likely, so taking it out for an inspection could do two things--give you a jump start on the replacement of the control box, and give you a chance to test and see if it was the problem.



Just for fun I looked up your model on ebay,

heater parts

While i didn't see your specific gas control there is an ad lower on the page of results for suppliers --often they can help you troubleshoot things and may have specific knowledge of common failures
 
Jen Fan
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Good info here. 

I'm leaning towards a clog- I feel like symptomatically the strange intermittent nature of the issue indicates a build-up that eventually got too thick to push through.  I was thinking of taking the piece off and blowing it out with an air compressor.  But I'll see what tools I can find for the job.  Maybe even a plain old pipe cleaner would work!  Either way, it's the most practical first step to take before replacing parts or servicing :)  I'll keep ya posted, thanks guys!  I appreciate it!
 
Jen Fan
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Thuogh I should note that the manual says to flip the black switch on the unit to "on" for electric mode.  The switch does nothing.  On or off, it still attempt gas ignition.  Hm...
 
bob day
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that switch may just control the blower since I doubt there could be an electric heater element
 
Walt Chase
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bob day wrote:that switch may just control the blower since I doubt there could be an electric heater element


That particular unit can be a dual heating unit.  Electric element and lp gas.  Or at least thats what google said when I googled the model number looking for info on the unit searching for answers to the question.  That said, it doesn't look like this one is equipped with an electric element.  The switch may be  to turn on the electric spark ignition.
 
bob day
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sorry, you're right,--I was writing about something else and  didn't catch the mistake,  thanks.
 
Jen Fan
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Yes, I believe this unit should be dual source, but it doesn't seem to switch out of gas mode.

I cleaned the propane valve thing; the curly Q.  It was definitely clogged shut.  Still not propane to the spark though :/  I keep trying it every now and again to see if the lines need to be charged or something, kind of like when you run out of propane and it takes a litlte bit to get the air out of the lines.  Something tells me that's not what's going on though, I'm just being hopeful. ..
 
bob day
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Did you try checking gas flow without the "curly q " attached

Think that there is a possibility the same stuff clogging the orifice might have also fouled the gas control?

 
Jen Fan
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bob day wrote:Did you try checking gas flow without the "curly q " attached

Think that there is a possibility the same stuff clogging the orifice might have also fouled the gas control?



Hm...  No I did not. I could give that a go.  Though I think it's safe to assume that the propane is not coming out because the part I cleaned is free and clear now.
 
bob day
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I know that a new gas control unit could be expensive.

you could try disconnecting the tube leading to the unit (there should be an immediate release of gas, so be ready to turn off the propane (or tighten everything back up right away.)

obviously if the gas line to the unit does not leak gas when disconnected there is a shut off or clog somewhere else

The only thing I can think of that might free the unit is to blow compressed air through in reverse. that would mean disconnecting the gas line and then turning on the heater so the valves open inside.

Then if you are able to get air through that way, you might try hooking it up to the gas again and see if gas flows through.

I would not hold out a lot of hope for that, but it is the only other thing I can think of short of replacing that unit

Also, I'm not an expert at the inner workings of those controls, so be on high alert for any malfunctions if the unit seems to start working again. I have only started to look inside one of those units, and the number of places things can go wrong are beyond my poor experience.

Again, there are times when things are just expensive, and the peace of mind from having a new control unit might be worth the expense
 
Walt Chase
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I am going to suggest that you  look up your WH and the control valve and see if the solenoids are replaceable.  The solenoids are what the wires are plugged in to on the control valve.  They are what allows gas through to the burner when the WH calls for heat.  I would compare the cost of replacing those, if replaceable, against the cost of a completely new valve.  I would hazard a guess that the valve will need replacing. 
 
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