Hello all,
I have a 2016 Cardinal 3825FL with a suburban furnace SF-42Q. I am having a problem in where it ignites and actually heats about 10% of the time. Now let me explain what happens, the blower kicks on, blows cold air then attempts to ignite, I smell the propane and no flame, it does this three times then goes to lockout mode. Checked fuses, breaker, voltage at the sail switch, board and voltage at the limit switch all are functioning properly. Also checked for debris in ports there is none. Cleared the propane lines and slowly turned them back on “nothing” So I figured maybe it’s the gap in the dsi? But here’s my issue Forest River thought it would be genius to bolt the furnace to 2x4’s to the coach on each side on brackets I can’t reach from inside or outside so even if I wanted to replace I couldn’t? Anyone else having a similar problem? Winter is coming fast and I have heaters but they won’t help me or my tanks from freezing in the snow. Also read the entire service manual for that model and they (Forest River) did a very sloppy and negligent install. Any help would be much appreciated. Thank you!!
Can you hear or see the spark when it's trying to light?
X2
If it is sparking but not lighting you'll need to check the electrode/gap
If it isn't sparking (clicking noise) then you'll have to explore why. (possible control module)
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slap the top of furnace box . this was the first thing i did when mine acted like that ,and it worked ever since. tighten the knob on hose to tank with a pair of chanelocks ,sometimes the safety valve doesnt compress all the way. ic it is windy that wont let it ignite also . cover vent with a 1/2 of a # 10 can or the like.
I also wanted to remove mine to service it myself. I have to tear my cabinets apart to get it out. Furnace was put in and hooked up before cabinets. I just use electric heat now.
Have you checked the propane system psi? Inches of WC. What elevation are you located MSL? Does this do it on either propane bottle?
A "far-and-wide search" should have turned this suggestion up, because I've posted it here at least a dozen times. This is real, practical experience, not theoretical.
The Suburban SF-series furnaces are EXTREMELY sensitive to propane pressure. And the propane pressure regulator (out by the tanks) generally fails after about 10 years +/-.
If you can hear the loud snap of the ignitor, the DSI is fine. I would even say that if it sometimes ignites that the DSI is fine. It sparks multiple times on each of the three tries, so even if it missed a few times, ignition will still take place.
If you're obsessive like me, you may want to really be sure before replacing parts. If that's the case, you can make a manometer, as I did. Pictures attached. Disconnect the propane feed at the furnace and hook this up instead. The lines are labelled as inches but are actually 1/2" apart. This is because the pressure raises one side by 1/2" and lowers the other side by 1/2". The measurement is the difference between the two sides.
Don't be fooled because the water heater and range seem to be working fine. The range has an internal regulator that lowers the pressure even further. This hides the fact that the main regulator pressure is out of spec. The water heater uses convection airflow and is relatively insensitive to gas pressure. The furnace uses forced airflow for combustion and the gas pressure has to be just right to ignite.
__________________
Larry
"Everybody's RV is not like your RV."
"Always take pictures with the button on the right."
"Always bypass the water heater before opening the low-point drains."
Sticks and Bricks: Raleigh, NC
2008 Cherokee 38P: at Ivor, VA permanently
We have a '21 FR E-PRO E19FD, bought 8/1/20. Our first trip this season (in May) we hit a cold snap and tried to use the propane heater with no luck. Clicking, blown cold air, no ignition. Camping World Kernersville NC replaced the igniter under warranty. No problem since.
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Hello all,
I have a 2016 Cardinal 3825FL with a suburban furnace SF-42Q. I am having a problem in where it ignites and actually heats about 10% of the time. Now let me explain what happens, the blower kicks on, blows cold air then attempts to ignite, I smell the propane and no flame, it does this three times then goes to lockout mode. Checked fuses, breaker, voltage at the sail switch, board and voltage at the limit switch all are functioning properly. Also checked for debris in ports there is none. Cleared the propane lines and slowly turned them back on “nothing” So I figured maybe it’s the gap in the dsi? But here’s my issue Forest River thought it would be genius to bolt the furnace to 2x4’s to the coach on each side on brackets I can’t reach from inside or outside so even if I wanted to replace I couldn’t? Anyone else having a similar problem? Winter is coming fast and I have heaters but they won’t help me or my tanks from freezing in the snow. Also read the entire service manual for that model and they (Forest River) did a very sloppy and negligent install. Any help would be much appreciated. Thank you!!
Ok with out readfing other posts i am guessing you have mud dubbers . built a nest on or by the burner . will need to pull unit . if you have an outside access it's pretty easy only one screw bottom center of furnace, disconnect gas and unit should slide out of enclosure be careful of wiring . disconnect gas valve line going to burner then the screws on the cover plate of the burner .
Does everything else work on propane, Fridge, Water heater, stove top, (oven, if equipped) ?
Uhh, did you read post #8 before posting that question? If the regulator is failing (quite common), the range and water heater will work fine, but the furnace won't. Go back and read post #8 to find out why.
__________________
Larry
"Everybody's RV is not like your RV."
"Always take pictures with the button on the right."
"Always bypass the water heater before opening the low-point drains."
Sticks and Bricks: Raleigh, NC
2008 Cherokee 38P: at Ivor, VA permanently
I am so sorry for the late reply to all the responses been working long hours. I checked the propane psi and the wc is 11 which is well within range for the furnace. You are right though the Suburbans are extremely sensitive. So I got it out after work and opened up the area to where the burner is located and it had a significant hole in the burner the dsi rod was 1/8” above burner and located 3/16” away from slat as stated in service manual. Also noticed a good amount of what was likely mud dabbers right in the inlet for the burner. Was unable to see if it starts tonight but will try tomorrow. I ordered a new burner as all other components in the chain seem to be functioning. The amount of help was just awesome though. I really appreciate it and I will keep you updated.
A "far-and-wide search" should have turned this suggestion up, because I've posted it here at least a dozen times. This is real, practical experience, not theoretical.
The Suburban SF-series furnaces are EXTREMELY sensitive to propane pressure. And the propane pressure regulator (out by the tanks) generally fails after about 10 years +/-.
If you can hear the loud snap of the ignitor, the DSI is fine. I would even say that if it sometimes ignites that the DSI is fine. It sparks multiple times on each of the three tries, so even if it missed a few times, ignition will still take place.
If you're obsessive like me, you may want to really be sure before replacing parts. If that's the case, you can make a manometer, as I did. Pictures attached. Disconnect the propane feed at the furnace and hook this up instead. The lines are labelled as inches but are actually 1/2" apart. This is because the pressure raises one side by 1/2" and lowers the other side by 1/2". The measurement is the difference between the two sides.
Don't be fooled because the water heater and range seem to be working fine. The range has an internal regulator that lowers the pressure even further. This hides the fact that the main regulator pressure is out of spec. The water heater uses convection airflow and is relatively insensitive to gas pressure. The furnace uses forced airflow for combustion and the gas pressure has to be just right to ignite.
Wow that was actually really helpful, I didn’t realize that the range has its own regulator and that the furnace used forced induction. I guess the forced induction would be common sense but I honestly didn’t think about it. I will try your setup. I should also mention I am hooked up to a “long stay” tank which houses about 350 gallons of propane. It passes from the companies regulator through my regulator. Wonder if the pressure is to high and the times it did ignite and was left on caused the hole in the burner from increased BTU’s. Now it failed to start at all because of the hole and pressure and bugs. Full disclaimer I have never had to use my furnace until I moved to MO from CA. I used portable heaters for 4 years because it never got below 32 degrees. I think it’s a combination. But am still going to take your advice and test pressure. Thank you so much for your help.
I work on these often and find bugs or debris such as a small spider web or dust in the burner itself. Sadly you have to disassemble the entire furnace with it out of the camper to access this on most models. When you get the burner out wash back-and-forth through it several times in the sink. Check the gap on the igniter. Scrub the other metal rod which is the flame sensor with a scotch Brite so it’s shiny and put it all back together
Yup. Check to make sure your furnace's sail switch is working properly.
If your mud dauber tenants have clogged either/both of the furnace's exterior vents, the sail switch won’t activate when the blower starts and the furnace will shut down.
A couple years back for my issue, I did what Mrbovernan mentioned and also found the sharp corner of my sail switch was getting hung up on the plastic housing. You can see the scratch mark. I filed that edge down. Not sure which thing actually fixed the issue but it worked upon reassembly.
Hello all,
I have a 2016 Cardinal 3825FL with a suburban furnace SF-42Q. I am having a problem in where it ignites and actually heats about 10% of the time. Now let me explain what happens, the blower kicks on, blows cold air then attempts to ignite, I smell the propane and no flame, it does this three times then goes to lockout mode. Checked fuses, breaker, voltage at the sail switch, board and voltage at the limit switch all are functioning properly. Also checked for debris in ports there is none. Cleared the propane lines and slowly turned them back on “nothing” So I figured maybe it’s the gap in the dsi? But here’s my issue Forest River thought it would be genius to bolt the furnace to 2x4’s to the coach on each side on brackets I can’t reach from inside or outside so even if I wanted to replace I couldn’t? Anyone else having a similar problem? Winter is coming fast and I have heaters but they won’t help me or my tanks from freezing in the snow. Also read the entire service manual for that model and they (Forest River) did a very sloppy and negligent install. Any help would be much appreciated. Thank you!!
My Suburban heater has two solenoid valves in the propane delivery system - they operate allow propane into the burn chamber, and will choke off the flow of propane if the ignition system fails. As it turned out, one of the solenoids was hanging up - the spring would not push that solenoid into position. Opening up the innards and manually forcing the solenoid to operate resulted in proper operation. There are a couple of gaskets involved in taking the heater apart in this manner, so treat them carefully.
My Suburban heater has two solenoid valves in the propane delivery system - they operate allow propane into the burn chamber, and will choke off the flow of propane if the ignition system fails. As it turned out, one of the solenoids was hanging up - the spring would not push that solenoid into position. Opening up the innards and manually forcing the solenoid to operate resulted in proper operation. There are a couple of gaskets involved in taking the heater apart in this manner, so treat them carefully.
Not sure what model surburban furnace you have but any that i have seen just have there own gas valve which is not serviceable and not recommended to take apart .
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