Suburban SF-30

[Keystoned]

I guess I just got lucky as the only part I could access was the limit switch. After disconnecting and reconnecting it on both sides, everything worked...except my ducting wants to heat the storage area more than the living quarters. That is my next project...

[BulletOwner1]

In my case when the furnace would not kick on the issue was the relay board, located in the roof AC unit. When I isolated the furnace from the thermostat and shorted the thermostat wires from the furnace, wa la, furnace worked. Got part number off the board, ordered from Amazon, replaced, easy peasy. Well sort of.

[Thoremilly]

The screen is probably rusted from rain water running in there, I had the same problem.

[sonofcy]

Originally Posted by jregalia11

No heat. Now I have watched you tube videos.. repaired the furnace once before and this time I am stumped.
I have a furnace that will bring the blower on,purge,then NO spark and then open the gas valve.
I have a new board and new spark igniter installed to eliminate a failed old part. Not a parts replacer but there can only be 3 things really wrong.
Maybe someone can help me.
I have made sure spacing is correct on the spark ignitor. 1/8 inch and also shined the light into the burner to line it up. Checked 13vdc. Now I am not getting any bolts of of the board where the spark ignitor is.
My last guess is the sail switch but... before I order one as a guess... correct me if I’m wrong and that the gas valve would not even open if the sail switch or high temp limit was OPEN. I do know the sail switches are the most common failure tho.
Btw have gas.. and gas pressure is proper.
At least it appears that way with other appliances.
No tick tick tick before the gas valve opens.

Searched for this issue before so sorry if it’s a repost but no one seems to ultimately ask the question... will the gas valve open even with a failed sail switch ? I don’t think so from what I have read but I could be an idiot. Ha.

Thanks in advanced.

Sounds like a board. Make sure you get a Dinosaur brand, they last unlike the others.
Available on amazon but go to the https://www.dinosaurelectronics.com website first and determine proper model, mine was fan50plus. I ordered a spare because it also works in my water heater after doing a jumper change.

[bspiek]

Originally Posted by JRTJH

DON'T DO THAT HOLDING THE CONNECTOR IN YOUR BARE FINGERS while wearing damp socks...…

Don’t even need wet socks.... but if you really want a good one use the ignition transformer on an oil burning furnace.....it’s like getting hit with a taser.

[bspiek]

What control boards are recommended? My furnace lights but doesn’t recognize the flame. I’ve done all of the cleaning and polishing like I do on a normal house furnace but none have worked.

[JRTJH]

Originally Posted by bspiek

What control boards are recommended? My furnace lights but doesn’t recognize the flame. I’ve done all of the cleaning and polishing like I do on a normal house furnace but none have worked.

You can download the Troubleshooting Guide here: http://bryantrv.com/docs2/docs/subsw.pdf

Page 14 has the LPG ignition sequence listed in full. The "section of ignition sequence" they omitted is the "flame sensor voltage". If the components (thermostat/limit/ECO switch, gas valve, ignitor/electrode and control board) are all working properly, the burner will ignite.

Cleaning a faulty flame sensor might cause it to work but also may not.

The entire process is dependent on having 12VDC at the control board connection and that there is no corrosion on any of the connections on the water heater. I've had several through the years that had corrosion on the thermostat/limit switch "blade plug connection" (under the black plastic cover) and others with corrosion on the electrical connectors on the gas valve and/or on the connectors on the control board on the back of the water heater.

Take a look at the ignitor/electrode assembly. It's also the flame sensor and produces a "microvoltage" that feeds back to the control board to confirm ignition and flame. If it doesn't sense a flame and send that voltage to the control board, the system will shut down.

From what you're saying, it sounds like the water heater is igniting, but then shutting down after a flame starts. It may be the electrode, the wiring back to the control board/gas valve or it could be a bad control board. I'd suspect it's likely to be "in the front part of the water heater where things stay wet and rusty" rather than the control board.

That said, if I were to buy a replacement board, I'd buy Dinosaur Electronics brand. They seem to be much more "robust and reliable" than OEM boards.

[bspiek]

Originally Posted by JRTJH

You can download the Troubleshooting Guide here: http://bryantrv.com/docs2/docs/subsw.pdf

Page 14 has the LPG ignition sequence listed in full. The "section of ignition sequence" they omitted is the "flame sensor voltage". If the components (thermostat/limit/ECO switch, gas valve, ignitor/electrode and control board) are all working properly, the burner will ignite.

Cleaning a faulty flame sensor might cause it to work but also may not.

The entire process is dependent on having 12VDC at the control board connection and that there is no corrosion on any of the connections on the water heater. I've had several through the years that had corrosion on the thermostat/limit switch "blade plug connection" (under the black plastic cover) and others with corrosion on the electrical connectors on the gas valve and/or on the connectors on the control board on the back of the water heater.

Take a look at the ignitor/electrode assembly. It's also the flame sensor and produces a "microvoltage" that feeds back to the control board to confirm ignition and flame. If it doesn't sense a flame and send that voltage to the control board, the system will shut down.

From what you're saying, it sounds like the water heater is igniting, but then shutting down after a flame starts. It may be the electrode, the wiring back to the control board/gas valve or it could be a bad control board. I'd suspect it's likely to be "in the front part of the water heater where things stay wet and rusty" rather than the control board.

That said, if I were to buy a replacement board, I'd buy Dinosaur Electronics brand. They seem to be much more "robust and reliable" than OEM boards.

I’ve had the furnace out 3 times and taken the burner and igniter and sensor assembly out and cleaned them. My holdup on ordering a control board has been me second guessing if it’s a grounding issue causing the flame sense failure.

Water heater works fine on both gas and electric though.

I brought the trailer home from winter storage yesterday so hopefully I can dig into it again this week.

Thanks for the tip on the dinosaur brand.

[JRTJH]

DUH !!!! My apologies... I read your post this morning "with" my first cup of coffee, and somehow I "read into it" that your water heater was the problem....

As for the furnace, If you've done all the troubleshooting, I'd recommend a Dinosaur board as a replacement there too. You can call Dinosaur Electronics tomorrow morning with your furnace model/serial number and they will tell you which board is the correct replacement. Their number is: (541) 994-4344 they are open 8-5, Pacific time.

[bspiek]

thank you Jtomanyletters, I’ll give them a call this week. Take care.