Join Date: Mar 2008
Location: Newport, TN
The agony & the ecstasy pt.2 - repairing our suburban sf-30 furnace (again!)
My original post on this topic was quite a popular post the last 3 years and I got some great feedback on this, as many have struggled with Suburban furnaces.
This post is here because the problems we thought we were having with our SF-30 not firing up were not resolved after all. And, by after all, I mean after doing all these things:
1. replacing the electronic controller with the Dinosaur Electronics upgraded version (a great product)
2. Removing the unit multiple times, even installing 12V automotive-style quick disconnects on the four main wires. At one point, out of desperation, we even took our furnace to a local RV shop for repair, only to have it returned as "it works fine for us" - when in fact they had not re-assembled it correctly and it squeaked like mad on the re-install, which required me to re-uninstall it for the umpteenth time and take it apart to find the squeak in the blower motor housing, re-assemble and reinstall.
which led to the Final Solution:
3. We Replaced the original dual pressure gas regulator at the tanks, which increased system gas pressure and improved the performance for a few seasons only. But, at this point, it was working so we THOUGHT the problem was solved.
We were SO WRONG!
This winter season the problems came back to roost again. Same symptoms, same problem. The burner would try to light, go tick-tick-tick, you could smell propane being vented out the exterior vent tube, but nothing happened. Maddening.
Based on my lesson learned from last time, I assumed (as I dont own a manometer) that the new Camco dual pressure regulator must have stopped producing the correct gas pressure. I bought another new one on Amazon - a super nice Italian made model with true visual gas level gauges and installed it. $50 and 1 hour later the furnace still would not light. Sigh. That meant that it sure wasnt the gas pressure!
So, I went back to the manuals for a review, as I was dreading the whole neck-straining, back-breaking furnace removal process, and tried to decide what parts to buy in advance so the repair would go quickly and smoothly (HA! -that never happens with a furnace repair!)
I bought a new ignitor w orange cable, a burner gasket and a sail switch - the later just in case, since you have to take it all apart anyway. I studied the manuals to remind myself of how the unit works and comes apart.
This weekend we did the dirty work. It was a super tedious job as everyone who has ever attempted it knows. Bleed off the gas line, remove the cover, remove the inner sheet metal cover and hold-down screws, then go under the fridge to disconnect the wires. Luckily I have the 4 quick disconnects, so this part was easier.
To get to the infamous Suburban electrode to check it with a flashlight LOOKS EASY IN THE MANUAL. It is anything but. Perhaps there is a way to dismantle the entire SF-30 that I am missing, to get to the area where the electrode assembly is located, but on mind, this simple task meant also removing the entire wheel blower motor cover and motor, several wire connectors and more, so that the entire stainless steel gas line and regulator can come loose, then removing the screws on the gasketed plate on the burner assembly where the ignitor lance lives. It was almost like brain surgery with much risk of breaking some part or not being able to figure out how to get it re-assembled.
Tip: we took lots of pics as we disassembled the unit on our workbench (which came in handy later) and used 3 seperate coffee mugs for the different sets of screws, so they did not get mixed up (one for the blower motor assembly, one for the burner gasket cover, etc.). I think I ended up using damn never half the small tools I own, so I hope you have more than just a screw driver and pliers when you attempt this.
Long story short, we finally got to the heart of the beast. We were able to remove the SS gas line assembly and regulator and the burner cover and its gasket (which definitely needed replacing anyway) and could see inside the infamous burner itself. The heart of darkness.
Surprisingly, there was a lot of soot inside there, even though I regularly try to vacuum it out via the outlet tube. I guess my idea is only half effective, as there were at least 2 teaspoons of black silt in the corner inside. But, we did find the problem. AS YOU MIGHT EXPECT, it can best be blamed on POOR QC at the SUBURBAN FACTORY in Tennessee. I have to call them as i see them and the RV dealer never dissembled this unit, as it had the original gasket on it. AND, here's the rub: The tip of the lance was not positioned correctly height-wise, nor horizontally either. It was quite obvious, on seeing this, WHY we have had so much trouble with this furnace since we bought our FR Wildwood from the original owner, who had only used it 6 times (so it was nearly brand new when we got it).
In fact, I did not need the ignitor I bought on Amazon, and returned it unopened. The original factory OEM ignitor was not corroded, it just needed to be bent into the correct position. (For the geeks out there, the tip of the lance as 0.250" above the face of the burner, rather than 0.125" and the tip of the lance was nowhere close to the holes in the burner where the gas comes out, so I am not sure how it ever worked right).
Anyway, replacing the ignitor lance assembly looked like a bear, as it is tightly wound in there and has grommets and such and is a job best avoided if not needed. Instead, we measured carefully and repositioned the ignitor lance, checked the gas orifice to be sure it was not clogged (it was fine), then cleaned up some minor rust on the burner (and learned that all burners likely get this minor rust over time), vacuumed up the black silt, installed the new burner access cover gasket, and then went through the 30 minute process of carefully reinstalling all the parts and pieces and wire connectors, back where they went originally, checking that the dual squirrel cage motor assembly was properly seated so it would not squeak, reattached the wire connectors, re-installed wire tires, and made sure every single OEM screw was back in its original location.
The re-assembly portion of the surgery went well, so with high spirits, we re-installed the SF-30 in our trailer, checking alignment with the internal air distribution duct, hooking up connections, and re-installing/re-caulking the outside vent hole cover and screens with its six screws. This took my wife and I another half hour to do. Wow, was that the job from Hell.
GREAT NEWS! After all this, it worked like a charm. Fired up on the first try! Fired up each and ever time thereafter. No leaks, no issues, no problems. We were nice and toasty warm all weekend long, and it was quite cold this weekend, so this was great!
LESSONS LEARNED: the position of the lance tip inside the burner can be very critical if your furnace will try to start, but not start, and you can hear the tick-tck-tick and smell the gas valve opening and can smell the propane. You have no spark and the lance tip of the ignitor creates that spark. If it is not the pressure from the regulator or a low tank, then you could end up needing the same repair.
And, this repair is not for the faint of heart. I recommend it only to appliance repair techs, propane techs, mechanical or electrical or robotic engineering graduates or Stephen Hawking. Everyone else should steer clear. This is not a user servicable item, really.
I say that as if you were to, for example, not buy a new gasket and try to get by on the cheap and reuse the original gasket, and if it leaked you would never see it, but you could be exposed to carbon monoxide inside your trailer. (Of course, we have a new CO sensor mounted at floor level within 2 feet of our unit, but I am not sure if this is standard for all RVs.)
Still, if yours is broken, and you have good tools and you have lots of time and patience and want to save the $120 you will probably have to pay, it is possible to do this job. It's just anything but easy or fun. Satisfying when its done and done right, though.
Its a shame that Suburban did not do a recall of the 2004-2005 SF-30s as might was clearly not set up at the factory, and since its installed as a unit, I dont see this as a FR screw up. This is all on Suburban.
While we had it apart, I snapped a few pictures of the burner, lance and probe, as the one in the Suburban manual is pretty useless and hard to interpret.Hope this helps someone else, even if just to decide to take the unit to the shop.
Pictures shows the dissembled SF-30 facing with the burner cover open, with the old gasket still attached. A 2nd pic shows the venturi that feeds the burner - it looks like a miniature space shuttle nozzle. A 3rd shows the actual lance itself, the tip of which is directly over the burner, which lies underneath the cover that is open. A 4th shows the stainless steel gas orifice and cover (the orifice looks like a brass pencil eraser).
Pretty amazing device really, and once the lance is set to 1/8" instead of 1/4" and is positioned as shown over the holes of the burner, it fires like clockwork! I expect that this will finally end all of our SF-30 troubles and we saved hundreds by not having to buy a NEW unit when there was nothing wrong with ours but an adjustment.