Suburban furnace issue UPDATE

[joshuajim]

I have a Suburban SF-30-F furnace with Domestic single zone thermostat in my 2011 Wildwood trailer. I'm making a trip to Arizona next week and when checking systems, it is not working.

Tests so far include verifying propane as cook top which is located directly above the furnace burns three burners full on.

When set to heat, blower kicks on and runs for about 10 seconds when I can hear the solenoid click. This would seem to indicate that the sail switch is operative. I can go outside at the exhaust and smell a faint smell of propane.

Furnace does not ignite and solenoid clicks off and furnace tries multiple times to ignite.

Suggestions on possible remedies?

OK, pulled the unit and it seems that there is no spark from the ignitor. Looks like a new board.

Guess it will be an electric heater in AZ. Fortunately 70's in the daytime, 40's at night.

[A1RVTraveler]

chinrv wrote:
Can a sail switch in a Suburban SF-30 be replaced without removing the furnace from the RV?

It all depends on the installation. If you have an outside access door to work on the furnace, you can remove the fan cover and replace the sail switch. If your furnace is installed from inside the RV and only the intake and exhaust pipes are visible from the outside of the RV, you will need to pull the furnace to get to the sail switch.

[chinrv]

Can a sail switch in a Suburban SF-30 be replaced without removing the furnace from the RV?

[joshuajim]

OK, new board and all is well. There is a little sales lot and mobile repair near me. Thought I would give them a try to see if they had a board as the next closest place that had one was 45 miles away.

Showed the owner my old board and he said "yep, I got one". His parts room was about 8 x 10 and every space was crammed with parts. He spends about 15 minutes looking for the board and finds several others that were not correct. Finally he says, "I'm sorry but I guess I don't have one". Then a flash occurs and he says " wait, I have a brand new furnace out in my storage shed, I'll pull the board out of it". He gets it, disassembles the furnace and pulls the board. It was new as it was still in the packaging.

Small town service doesn't get any better than that!

[joshuajim]

OP hers. One last check. I have 13.2v to the board but only 10v at the red/yellow connector. Specs say 12 volts there.

[drsteve]

dougrainer wrote:

joshuajim wrote:

dougrainer wrote:
You disconnect the spark Electrode wire from the Control Board IgnitorPiezo tower. Turn off the LP or disconnect the 12 volt feed to the Gas Solenoid. Start the Furnace cycle. Use a LONG handle screwdriver with an insulated (wood/Fiberglass) handle and holdthe metal end of the screwdriver about 1/4 inch from the Piezo Tower spade. IF you get a strong spark your board is OK and your problem is either a bad electrode(not likely) or most common,anInsect nest on the burner and stopping the electrode gap for the spark. Doug

Thanks for your input. I pulled the cover off the burner/electrode area and the area is clean and the electrode is about 1/8" above it. Out here in the desert we don't have mud daubers. No mud. ??

Mud Daubers are NOT the only varmint/insect that gets into a LP appliance. Doug

Yup. Spiders love propane. They build nests inside burner tubes, or just crawl in and die.

[enblethen]

Second recommendation for Dinosaur Electronics replacement circuit board

[joshuajim]

wa8yxm wrote:
There are several threads around here with a full diagnostic procedure, I worked one up myself and posted it several times. Mine is specificc to a Dometic but for this Surburan is identical.... In fact even teh control board I had to replace... FITS SELECTED SURBURANS.

Since you've done half hte uob

Suspects: Propane flow. Is the orifice clear or clogged, an insect likes to nest there.

Spark gap. often too big no spark = no ignition.

Now in my case Ignition happened but the control board did not sense it.
This can happen due to a very dirty sensor or a bad sensor.

in my case it was a bad control board so I went with Dinosaur Boards replacement

NOTE bad control board can also fail to spark,, Since that's where it comes from.

All good recommendations. It definitely is lack of spark. Even if there was no gas, it should still have spark. The electrode is within 1/8" of the burner and the cable is less than 1 ohm so continuity is good from the board to the electrode.

I'm 99 and 44/100% sure its the board. 😉

[dougrainer]

joshuajim wrote:

dougrainer wrote:
You disconnect the spark Electrode wire from the Control Board IgnitorPiezo tower. Turn off the LP or disconnect the 12 volt feed to the Gas Solenoid. Start the Furnace cycle. Use a LONG handle screwdriver with an insulated (wood/Fiberglass) handle and holdthe metal end of the screwdriver about 1/4 inch from the Piezo Tower spade. IF you get a strong spark your board is OK and your problem is either a bad electrode(not likely) or most common,anInsect nest on the burner and stopping the electrode gap for the spark. Doug

Thanks for your input. I pulled the cover off the burner/electrode area and the area is clean and the electrode is about 1/8" above it. Out here in the desert we don't have mud daubers. No mud. ??

Mud Daubers are NOT the only varmint/insect that gets into a LP appliance. Doug

[wa8yxm]

There are several threads around here with a full diagnostic procedure, I worked one up myself and posted it several times. Mine is specificc to a Dometic but for this Surburan is identical.... In fact even teh control board I had to replace... FITS SELECTED SURBURANS.

Since you've done half hte uob

Suspects: Propane flow. Is the orifice clear or clogged, an insect likes to nest there.

Spark gap. often too big no spark = no ignition.

Now in my case Ignition happened but the control board did not sense it.
This can happen due to a very dirty sensor or a bad sensor.

in my case it was a bad control board so I went with Dinosaur Boards replacement

NOTE bad control board can also fail to spark,, Since that's where it comes from.

[enblethen]

Have you tested the electrode cable?

[joshuajim]

dougrainer wrote:
You disconnect the spark Electrode wire from the Control Board IgnitorPiezo tower. Turn off the LP or disconnect the 12 volt feed to the Gas Solenoid. Start the Furnace cycle. Use a LONG handle screwdriver with an insulated (wood/Fiberglass) handle and holdthe metal end of the screwdriver about 1/4 inch from the Piezo Tower spade. IF you get a strong spark your board is OK and your problem is either a bad electrode(not likely) or most common,anInsect nest on the burner and stopping the electrode gap for the spark. Doug

Thanks for your input. I pulled the cover off the burner/electrode area and the area is clean and the electrode is about 1/8" above it. Out here in the desert we don't have mud daubers. No mud. ??

[ChuckV1]

My symptoms were the same as what you describe, I had a bad Control Board

Safe Travels

[dougrainer]

You disconnect the spark Electrode wire from the Control Board IgnitorPiezo tower. Turn off the LP or disconnect the 12 volt feed to the Gas Solenoid. Start the Furnace cycle. Use a LONG handle screwdriver with an insulated (wood/Fiberglass) handle and holdthe metal end of the screwdriver about 1/4 inch from the Piezo Tower spade. IF you get a strong spark your board is OK and your problem is either a bad electrode(not likely) or most common,anInsect nest on the burner and stopping the electrode gap for the spark. Doug

[Old-Biscuit]

Could just be a bad spark electrode...