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

Chris Lyons wrote:Did the new part fix it?

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Thanks for checking in  Yes, I replaced the gas valve and it's been working perfect since!  I guess that repair guy at Northwood doesn't know they can blow out on you

That's great!  Sometimes the experts are not the experts.  Could you please share where you found the part?  I have a similar water heater and I see the gas valve listed at $179 which I think is too much.

Chris Lyons wrote:That's great!  Sometimes the experts are not the experts.  Could you please share where you found the part?  I have a similar water heater and I see the gas valve listed at $179 which I think is too much.

I found the part searching on Amazon, using the heater model# and filtering through parts until I found it.  Once I found the part and figured out what it was properly called I took the name and part# over to ebay and found a good deal.  $45 I think I paid.  It was more expensive on Amazon.  You might find a better deal yet searching the bowels of the internet, but usually someone's got the best price on ebay somewhere!  

I want to add that in retrospect I think the problem originated with a clog.  The gas pipe was definitely clogged shut when I cleaned it out.  I image the unit trying to regulate gas through a clogged pipe was taxed and it ended up burning the part out.  Just a guess, but it seems likely to me!

Thanks, I ordered the gas valve and an anode.  Mine won't shut off completely.  Always a sooty flame dancing at the orifice.

Chris Lyons wrote:Thanks, I ordered the gas valve and an anode.  Mine won't shut off completely.  Always a sooty flame dancing at the orifice.

Oh my!  Sounds like it could definitely be the same problem I had with the gas valve  malfunctioning.  Though, have you checked the thermostat?  If the thermostat isn't registering that the tank is up to temp is wouldn't be signaling to shut off the gas flow.  

As far as I know the thermostat is working.  When it clicks on the burner roars.  When it clicks off a little bit of gas leaks through the gas valve.  It looks like a sooty candle flame.  I did some banging on the heater and the leak is much smaller now.  This tells me the gas valve is sticking inside.

Chris Lyons wrote:As far as I know the thermostat is working.  When it clicks on the burner roars.  When it clicks off a little bit of gas leaks through the gas valve.  It looks like a sooty candle flame.  I did some banging on the heater and the leak is much smaller now.  This tells me the gas valve is sticking inside.

That makes sense- hopefully the new part works!  Keep us posted!

Fixed!  New gas valve installed and replaced the anode.  The bottom of the tank was covered in sludge from the aluminum anode.  I replaced it with a magnesium one.  I also cleaned out the burn chamber which had lots of rust and debris.  

Hm...  Well, now my furnace has stopped working!  Of course it happens 2 days after my space heater stopped working.  I haven't torn it apart yet, but when it attempts to ignite there's a "mini propane explosion" sound- you know, like if you let the stovetop prime too long before sparking and the flames pop and roar through the air for a brief moment.  But then the pilot goes out.  It does it over and over; ignite, WHOOOSSSHHHH, then die.  The fan will kick on and it will run like it's working but it will produce no heat, as there is no flame.  

It was having no troubles or unreliability leading up to this.  Any ideas are welcome!  I might not tear into it until spring but I will post here when I do.  It's warming up and my back-up space heater keeps the trailer plenty toasty.

edited to stress that there's no actual explosion and I'm not implying that I leave the stovetop on until flames fill the air xD  I worded that badly.  But you know what I mean, right?

What is the make and model number of your furnace?  

Jen Fan wrote:

I have the same problem (propane in the mainline to other appliances but none at the pilot on the water heater)... can you mark the gas valve that you replaced on the pic?

Li El wrote:

I have the same problem (propane in the mainline to other appliances but none at the pilot on the water heater)... can you mark the gas valve that you replaced on the pic?

If you look at the photo, the unit with the two red wires and two blue going into it is the part I replaced.

Well I never dug into my furnace.  Didn't live in the trailer this year so it's been off the radar.  Possibly a next-spring project!

Chris Lyons wrote:What is the make and model number of your furnace?  

I was going to put the furnace thing off but it's back on my radar now, ironically, just as I decided I wasn't going to mess with it!

I'm not certain of the model number but it's a Suburban Propane heater, and the Northwood manufacturer I spoke with said it should be a 25,000 BTU furance.  They don't advise on furnaces.  I called Suburan Propane and they're not allowed to encourage home-repairs.

Any thoughts?

> "propane explosion..." [when trying to start]

Not lighting off properly. May not be getting enough gas from the control (a trickle vs. a flow) or the burner may be rusted and dirty and not flowing properly. Too little gas flow will not reach the pilot and instead will "leak" out and accumulate in the bottom of the combustion chamber until it rises to the level of the pilot. At that time there can be a _lot_ of propane sitting there and when it does light off...

Or. The pilot may not be positioned right or it may be too small. I think what you're experiencing is called "rollout" because flames roll out of the combustion chamber through the intake slots.

Or. Fuel contamination may be causing problems for your control. The below is just one link referencing (in this case) a propane engine with fuel problems - there are many more links to be found especially on RV sites.
https://www.eng-tips.com/viewthread.cfm?qid=377784

The situation is potentially dangerous.

Rufus

Rufus Laggren wrote:> "propane explosion..." [when trying to start]

Not lighting off properly. May not be getting enough gas from the control (a trickle vs. a flow) or the burner may be rusted and dirty and not flowing properly. Too little gas flow will not reach the pilot and instead will "leak" out and accumulate in the bottom of the combustion chamber until it rises to the level of the pilot. At that time there can be a _lot_ of propane sitting there and when it does light off...

Or. The pilot may not be positioned right or it may be too small. I think what you're experiencing is called "rollout" because flames roll out of the combustion chamber through the intake slots.

Or. Fuel contamination may be causing problems for your control. The below is just one link referencing (in this case) a propane engine with fuel problems - there are many more links to be found especially on RV sites.
https://www.eng-tips.com/viewthread.cfm?qid=377784

The situation is potentially dangerous.

Rufus

I really appreciate the response, thank you

All other gas appliances are working perfectly.  It's probably not the propane nor air in the lines.  The furnace also ran beautifully for over a year.  It stopped working after it had been sitting in one spot for 4 months. So I don't think the pilot is misaligned or too small in light of this?

The mention of propane trickling in and building up sounds like it explains what I'm experiencing.  I tried busting into this thing and I don't see much access to it.  I guess my next/first step is figuring out how to open it up!  I'll have to start doing some digging on a model...

Check the easy/quick/cheap stuff first.

- light the pilot and observe it for healthiness
- got plenty propane in tank?
- other stuff (like stove) working?
- tap the control smartly w/the handle of a kitchen knife (that administers about the right level of violence...) and try again
- open/close the shutoff valve for the furnace a couple times
- twist the control knob on/off a couple times
- using a good light and maybe a mirror, look closely at the burner to make sure something didn't dirty it up, all the little holes are clear
- check the slider or twister on the primary air supply (on the larger tube that feeds the burner); the type of adjustment varies but there's usually one there; prolly s/b "medium"

All the above can be done w/out dismantling anything much. If  you can observe the problem w/out getting singed, lie down so you can see into the combustion chamber and turn the control to "on" while watching what happens. Does the pilot remain healthy when the gas first comes on (b4 the pop when it gets blown out)?

The issue sounds like gas delivery and the above can indicate where to start looking. If there's no other appliance (that's working ok) on that propane tank, try switching tanks.

Best luck

Rufus

Rufus Laggren wrote:Check the easy/quick/cheap stuff first.

- light the pilot and observe it for healthiness
- got plenty propane in tank?
- other stuff (like stove) working?
- tap the control smartly w/the handle of a kitchen knife (that administers about the right level of violence...) and try again
- open/close the shutoff valve for the furnace a couple times
- twist the control knob on/off a couple times
- using a good light and maybe a mirror, look closely at the burner to make sure something didn't dirty it up, all the little holes are clear
- check the slider or twister on the primary air supply (on the larger tube that feeds the burner); the type of adjustment varies but there's usually one there; prolly s/b "medium"

All the above can be done w/out dismantling anything much. If  you can observe the problem w/out getting singed, lie down so you can see into the combustion chamber and turn the control to "on" while watching what happens. Does the pilot remain healthy when the gas first comes on (b4 the pop when it gets blown out)?

The issue sounds like gas delivery and the above can indicate where to start looking. If there's no other appliance (that's working ok) on that propane tank, try switching tanks.

Best luck

Rufus

Thanks for the tips!  I'm back to the prospect of fixing this... again.  lol.  It comes and goes on the priority list.  But I 'am' fixing a few little nickle and dime things so I wanted to revisit the furnace issue.

- light the pilot and observe it for healthiness < There is no 'constant pilot', it ignites when turned on.  Does this mean there is no pilot at all?  Or is it just a pilot that isn't constant?  Not sure on the terminology here
- got plenty propane in tank? < Yep!
- other stuff (like stove) working? < Perfectly!
- tap the control smartly w/the handle of a kitchen knife (that administers about the right level of violence...) and try again < will give it a go
- open/close the shutoff valve for the furnace a couple times < I have no idea where the shutoff valve is.  The furnace is under the propane stove in a cubby about 8" tall, 18" wide, and 24" deep (roughly).  It's basically a little silver box with a face plate that screws off.  There's no other access to it that I know of.
- twist the control knob on/off a couple times < no idea where this is either
- using a good light and maybe a mirror, look closely at the burner to make sure something didn't dirty it up, all the little holes are clear < Good advice, if I can find the pilot and burner
- check the slider or twister on the primary air supply (on the larger tube that feeds the burner); the type of adjustment varies but there's usually one there; prolly s/b "medium" < Where would the primary air supply be?

I will get some photos in the next day or three if anyone's interested in digging into this more

Hi Jen,

You say there is a pilot that lights--presumably while you are pressing the gas button,  but then turns off when you let go of the gas  starting button?

That sounds like it could be a problem with the  heat sensor in the pilot assembly, and that problem might be fixed by as little as moving that metal prong around that senses when there is a flame so it tells the valve to stay open, or close down because the pilot flame is out.

I have corrected this problem in different ways on different appliances, sometimes the sensors are sort of spring clipped in place and the clip has slipped out of it's notches so the sensor is actually not in the flame enough and just tells the valve to shut down because it never heats up enough to open the regular supply..

On another appliance I had to manipulate the gas sleeve that delivers the pilot gas so that the pilot  flame slightly shifted position and contacted that sensor more directly.

Those adjustments will require access to the back of the unit though, so if you can't even look in there how would you adjust anything?

Some way or another you need to get access to  where the pilot and burner assembly are so you can see more clearly what is going on.

Whatever else might be wrong, this would seem to be a first step.

bob day wrote:Hi Jen,

You say there is a pilot that lights--presumably while you are pressing the gas button,  but then turns off when you let go of the gas  starting button?

That sounds like it could be a problem with the  heat sensor in the pilot assembly, and that problem might be fixed by as little as moving that metal prong around that senses when there is a flame so it tells the valve to stay open, or close down because the pilot flame is out.

I have corrected this problem in different ways on different appliances, sometimes the sensors are sort of spring clipped in place and the clip has slipped out of it's notches so the sensor is actually not in the flame enough and just tells the valve to shut down because it never heats up enough to open the regular supply..

On another appliance I had to manipulate the gas sleeve that delivers the pilot gas so that the pilot  flame slightly shifted position and contacted that sensor more directly.

Those adjustments will require access to the back of the unit though, so if you can't even look in there how would you adjust anything?

Some way or another you need to get access to  where the pilot and burner assembly are so you can see more clearly what is going on.

Whatever else might be wrong, this would seem to be a first step.

The furnace is fully automatic and thermostat controlled.  So the only way to turn it on is to set it to "heat" on the thermostat, then set it to a temp below ambient temp.  There is no starting button or constant pilot.  When the thermostat calls for heat, the furnace fan immediately kicks on, then the furnace primes, sparks, and ignites.  And the heat begins.  So what's happening is when the thermostat calls for heat, the fan kick on, the furnace primes, sparks, and SOMETIMES ignites.  You can hear the spark and you can hear it when it does ignite.  Most of the time it sparks over and over and over but can't ignite.  Sometimes it does ignite, stays lit for a short period (like under 1 minute) then you hear a WOOOOOSH like a sudden burp of propane igniting and then the pilot goes out and no more heat.

So something is obstructing propane flow.  It might be a clog or it might be a regulator, like the gas valve on my water heater.    And the things you've suggested are good starting points :)

I don't know how this furnace works though.  The pilot for the water heater (which is also auto ignite, not constant) is accessible from the outside of the RV; it's the system photographed earlier in this post.  But unless the furnace shares this same system (I don't think so?  But maybe I just never noticed?) I think all of its functions are self-contained in the unit?

guess I'm showing my age suggesting there is a constant pilot, so most of what I said is probably not worth much. although there is still likely a sensor to tell the gas supply if there is a flame or not, it is probably somewhere near/ above the actual burner unit.  I remember this thread vaguely, and must have added something to it many moons ago, but don't remember that much of what was said earlier.

from what you just said, it could still be either thermostat or sensor or valve/ regulator, all those things are possible--without really knowing much about auto ignition, it might also be something like a power supply , loose wire, short,  or simply a bad computer /circuit board. It might even be something in the main electrical  fuse box if the circuit breaker  supplying the heater is starting to fail, those intermittent effects in the heater might be a symptom of something else altogether

sorry I don't have more experience with those systems, but at least I'm keeping the post front and center for others to see :-)