Suburban NT-16SE furnace won't ignite

[Ruck_and_Roll]

I have a 2008 Hawk with a Suburban NT-16SE Furnance

This appears to be a new problem although since July when I've owned the Hawk I've never had a need for a furnace....well now its September and I'm in the Colorado high country often....and I'm starting to get cold.....furnace would be nice

Turn the propane on, thermostat is on, furnace fans turn on, and then the igniting click cycles begin. I see a spark, but a flame doesn't establish.

Consulted the troubleshooting manual http://www.bdub.net/manuals/Suburban_Service_Manual.pdf
but not overly helpful. Before taking it out and cleaning or adjusting the electrode it I want to make sure I'm not missing an easy fix.

1. Electrical- I don't believe it to be electrical, when I turn the thermostat on, the fans kick in and it goes through the ignition cycle - so I don't think it is the sail switch. Have tried with both AC and DC, and fan/ignition cycle still occur.
2. Gas pressure- I did recently get the tank topped off. I ran gas through the stove fine. Stove does not auto fire on "light" (is it supposed to?). Fridge on propane works (that is another story). Tried the "bleed trick" I read about on another post- didn't work.
3. Electrode positioning?

Thanks,

Luke

 

[RickD]

Is this a new install or a furnace you haven't used before? This may be the same problem I ran into last spring on a new install. Turned out to be the sail switch. My brand new one actually had the wrong one in it from the factory. You can test the switch by removing it but leave it hooked up outside the fan box and closing it manually. You can try adjusting it by bending the arm a small amount. These things are really fussy.

Rick

 

[CougarCouple]

Hello Ruck n Roll
Another post had the battery cables reversed, also might be the safety check in the propane bottle. Shut off, open stove and wait 5 min. Shut off stove and slowly open valve on bottle.

Hope this helps.

 

[Old Crow]

Hi, Luke--

I see page 29 of the manual has these troubleshooting steps...

-----

2. Electrode sparking, but gas not coming through burner:

a. Check to see if voltage is coming out of module board to gas valve after the 12 - 18 second delay. Check the wires in the molex connector to be sure they are intact and making contact with the module board. Check wire from the module board to valve for continuity. Wire and connections check OK - replace module board.

b. Voltage is coming out of module board to gas valve, but gas valve does not open - replace gas valve.

3. Electrode sparking and gas valve opening, but burner will not light:

a. Check to see if gas is coming through to the burner. This can be accomplished by using a flow meter in the gas supply line. If no gas is coming through the burner, check for obstruction in gas line, in main burner orifice, or in main burner.

b. Gas is coming through burner, but spark will still not ignite burner - check gas pressure. Line Pressure - Min. 11" W.C.*, Max. 14" W.C. To properly check pressure, first determine the line pressure, cycle furnace and check pressure drop on demand. The drop in pressure should not be more than ½" W.C. A drop of more than 1/2" would indicate a faulty regulator, a restriction in the gas line, or a pinched gas line. Excessive pressure drop could also be due to moisture contamination.

-------

I'd first try to determine if the gas valve is opening or not. When I had an electrode problem on my Atwood, I noticed I could both hear and smell when the gas valve opened during the ignition sequence. With the outside cover off, I had my wife turn the thermostat up while I listened and timed the sequence. I heard the gas valve open and could smell gas there near the burner.

Also- I'd pull the board and clean the contacts with a pencil eraser and (if you have it) electronics cleaning spray (DeoxIt or similar) (and while you're at it, clean and check wiring connections)

Also- you say your stove works. If you turn on multiple burners, do the flames look normal or is there more yellow than you normally see? And do the flames sound right?
.

 

[Ruck_and_Roll]

Hello Ruck n Roll
Another post had the battery cables reversed, also might be the safety check in the propane bottle. Shut off, open stove and wait 5 min. Shut off stove and slowly open valve on bottle.

Hope this helps.

will try this

Is this a new install or a furnace you haven't used before? This may be the same problem I ran into last spring on a new install. Turned out to be the sail switch. My brand new one actually had the wrong one in it from the factory. You can test the switch by removing it but leave it hooked up outside the fan box and closing it manually. You can try adjusting it by bending the arm a small amount. These things are really fussy.

Rick

just a furnance I haven't used before

Hi, Luke--

I see page 29 of the manual has these troubleshooting steps...

-----

2. Electrode sparking, but gas not coming through burner:

a. Check to see if voltage is coming out of module board to gas valve after the 12 - 18 second delay. Check the wires in the molex connector to be sure they are intact and making contact with the module board. Check wire from the module board to valve for continuity. Wire and connections check OK - replace module board.

b. Voltage is coming out of module board to gas valve, but gas valve does not open - replace gas valve.

3. Electrode sparking and gas valve opening, but burner will not light:

a. Check to see if gas is coming through to the burner. This can be accomplished by using a flow meter in the gas supply line. If no gas is coming through the burner, check for obstruction in gas line, in main burner orifice, or in main burner.

b. Gas is coming through burner, but spark will still not ignite burner - check gas pressure. Line Pressure - Min. 11" W.C.*, Max. 14" W.C. To properly check pressure, first determine the line pressure, cycle furnace and check pressure drop on demand. The drop in pressure should not be more than ½" W.C. A drop of more than 1/2" would indicate a faulty regulator, a restriction in the gas line, or a pinched gas line. Excessive pressure drop could also be due to moisture contamination.

-------

I'd first try to determine if the gas valve is opening or not. When I had an electrode problem on my Atwood, I noticed I could both hear and smell when the gas valve opened during the ignition sequence. With the outside cover off, I had my wife turn the thermostat up while I listened and timed the sequence. I heard the gas valve open and could smell gas there near the burner.

Also- I'd pull the board and clean the contacts with a pencil eraser and (if you have it) electronics cleaning spray (DeoxIt or similar) (and while you're at it, clean and check wiring connections)

Also- you say your stove works. If you turn on multiple burners, do the flames look normal or is there more yellow than you normally see? And do the flames sound right?
.

looks like I will pull the board and check things-

flames look completely normal as far as I can tell, but I don't have much context to go by. I probably have camped in it 10-12 times since I got it in July but have only used the stove burners about half the time.

 

[Stan@FourWheel]

If you are getting fan and getting spark, it will NOT be the sail switch.

If you get fan and spark, but no ignition, for some reason you are not getting propane to it.

Try pulling off the front cover, finding the small reset switch, and resetting it.

That probably won't work, but I always do that first.

Then check your propane supply.


.

 

[Vic Harder]

Old Crow, gotta say I love your posts. Very helpful!

 

[ClimberRob]

Great post by Old Crow.

Are you positive you're getting spark? I have the same furnace. Mine is very picky about voltage, as well as gas flow. I have to run the stove before I use mine, or I have a similar problem. Also, if the voltage to the furnace is too low, which can be caused by either a low battery OR other draws at the same time (lights, fridge, etc. on) my heater will go through the startup cycle, but then shut down without actually firing up. Once I changed over to a LiFePo battery, I no longer had that issue.

 

[Ruck_and_Roll]

Thanks to all. Turned out to be an easy fix. I removed the burner access door and just tried changing the orientation of the spark electrode more drastically that I had previously. I was able to eventually get ignition. It may be a little finicky going forward but definitely maintained ignition. It must have gotten bumped around and dislodged from its proper orientation somehow.

Now my only question is that there where was some sort of thin material that was used to seal the burner access door. I am guessing this is used to get a real solid seal. It was pretty flimsy and frayed and just sort of fell apart when I accessed the door. I am sure it is some sort of flame retardant material. Anyone have any idea what this is? (pic attached) Seems like a good thing to replace/reseal...



Best,

Luke

 

[Old Crow]

This Amazon listing says this gasket is for some of the NT series models including NT-16S so I'd think that would be the one you need...


Suburban 071076 Electrode/Door Burner Gasket

I see they also have the electrode for that model if there was any question about the condition of yours.


Suburban 231931 Electrode

Glad to see you found the problem!

.

 

[Ruck_and_Roll]

Thanks Old Crow. Easier to find than I thought! There was a significant amount of play with the electrode w/in the gasket assembly, which to me doesn't seem normal. I am going to order both. I am wondering if the spark electrode became misshaped or distorted somehow or if a new gasket does a better job maintaining the electrode in the optimal position....again, tough for me to say, as I don't have much context into what these look like new.

This Amazon listing says this gasket is for some of the NT series models including NT-16S so I'd think that would be the one you need...

Suburban 071076 Electrode/Door Burner Gasket

I see they also have the electrode for that model if there was any question about the condition of yours.

Suburban 231931 Electrode

Glad to see you found the problem!

.

 

[patrkbukly]

Altitude.

 

[Ruck_and_Roll]

It ended up being the sparker electrode. I put the new one in and it fires up perfectly. It fits snug now, and does not freely rotate. The new one looked to be secured by a washer/gasket type assembly that did not allow it to freely rotate. The old one did not have this washer and had a lot of play in it. Nice to have heat!

Altitude.