The agony & the ecstasy pt.2 - repairing our suburban sf-30 furnace (again!)

[walk_the_walk]

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.

[Bama Rambler]

I read through that entire thing, and am I glad I did. Good job on finding and fixing the problem. It will no doubt help someone in the future (Including me).

I am going to tackle my BIL's furnace in the next few weeks because it won't fire.

[B and B]

This post should be pinned. Great explanation and good tech skills on your part to take this on!

[walk_the_walk]

Thanks for your comments and compliments.

I was able to find the Suburban parts I needed (burner gasket, sail switch and replacement electrode) on Amazon.com at a great price and returned two of those parts unopened for a refund. Since its hard to know what you will need in advance in this scenario, (and my trailer is way out in the sticks) Amazon came in really handy.

Also keeping the different screws separated and taking lots of pictures as you take it apart, are essential.

[youroo]

If someone knows how to attach this to the Member in Ca. For Ref! Thanks,Youroo!!

[fonzie]

Originally Posted by youroo

If someone knows how to attach this to the Member in Ca. For Ref! Thanks,Youroo!!

done

[youroo]

Originally Posted by B and B

This post should be pinned. Great explanation and good tech skills on your part to take this on!

I totally agree,this should be under Suburban furnace! Youroo!!

[Webgypsy]

Thanks to the folks that sent me to your thread. I too have had a brand new Rockwood 5th wheel with a heater that functions rarely. I posted my problem last night and was sent to your thread.
I am a 61 yr. old woman that lives alone in my Forest River Rockwood 5th wheel. I have done everything to repair this Suburban furnace that I am physically capable of. Pulling the entire unit is unfeasible alone.

I am freezing and at my wits end. I suppose if the only problem were the heater I could continue but this was a lemon off the lot.

I have been told it cannot be pulled and bench repaired by one technician and told by another he will pull it and bench test it.
$120.00 would be cheap cheap cheap. I am getting quotes from $300. to $850.

I continue to throw money at this thing with no positive results. I have looked for alternatives and can't find anything legal in CA.

So far I have:
*Dealer replaced three times but never reported failures to Suburban so they told me to fly a kite.
* Dealer replaced sail switch and never reported to Suburban
* Dealer replaced PC board and never reported to Suburban
* Dealer replaced limit switch and may have reported to Suburban
Dealer's technician walked away, said it was repaired and I went another winter with no heat.
* I found that the igniter was too far from incoming propane so I took it apart and bent it down and it started lighting
* Runs 5 minutes and shuts down. Wait ten minutes, play with thermostat and it might come back on.
*I replaced limit switch and thermostat quit working
*I replaced thermostat with exact Coleman-Mach model
*Heater now lights and warms. While running it randomly clicks as if it is trying to light again. It shuts off long before room temperature is up and will stay off unless I wait ten minutes and play with the thermostat.

I have concluded I am unable to fix this myself. Do I choose the person that says you should not bench test the heater and only work on it in the RV or do I hire the guy that says he will pull it and bench test it?

[Herk7769]

Much thanks to Walk the Walk.

I merged and edited his posts into a complete thread to add to the FAQ section.
This way anyone looking for Furnace repair help can see the entire flow of his troubleshooting in one place.

http://www.forestriverforums.com/for...ce-100883.html

[MNtraveler]

Wonderful news and report. I believe you have earned a cape after this kind of adventure and success!


Land of 10,000 Lakes
2016 Forester MBS 2401R

[walk_the_walk]

EPILOGUE: If all of this Agony and Ecstasy were not enough to warrant me a CE credit in Suburban RV Furnace repair at the very least, we went camping again last weekend, and believe it or not, it was cold in North Florida, and got down into the upper 40s.

So, I went to light up the newly repaired (or is it re-re-re-repaired) Suburban furnace, and I'll be damned if I COULD NOT GET IT TO FIRE UP. Click, click, click, click.... reset... click, click, click, click.

The thought of having to PULL this unit and take it apart again made me want to vomit, but I calmed myself and started troubleshooting the issue. I recalled reading somewhere online a tip from a fellow RVer who said that if you can hear the clicking and smell the propane at the exterior vent pipe, that it helps sometimes to partially cover the intake pipe with your hand (like you would do to a lawnmower carburetor), to essentially "choke" the air flow to get it to light. That worked! And, while I dont recommend it as any kind of permanent solution, or for the faint of heart, I had heat right away and the burner was churning out a nice hot flame.

And, it led me to the problem that was causing the furnace not to fire up. Now, keep in mind, the furnace was removed at least 4 times, I replaced the controller board with the Dinosaur Electronics board (a great product!), I took it to the shop, I fixed it after the shop screwed it up, and I bought a new dual pressure regulator made in Italy, and then took it apart again to replace the electrode, only to have to clean out the soot, clean and ADJUST the electrode position, and replace the gasket by the electrode port, and then reinstall.

So, after all that.... drum roll... the problem this time I determined was low propane fuel in the tank. I noticed a strong odor in the propane exhaust of the chemical tracer that is added to propane, and also that the flame at the stove had a slight orange tint to the flame tips. I theorized that the tank was low. After I switched to the 2nd tank, the problem disappeared. The furnace fired up several times on its own with no issues whatsoever, and we ended up using it for 3 more days. No more "choke throttling" required either.

And, it worked great this weekend, too.

THE MORAL OF THIS EPILOGUE is that LOW PROPANE IN THE SUPPLY TANK, as well as LOW PRESSURE, and MISALIGNED ELECTRODE are the most common problems with these units.

It's probably not the sail switch, the controller board or the thermostat. Use your logical troubleshooting skills and dont always rely on what the dealer rep says. After all, did they get trained at Suburban, or just on the job? Some of them are great, and some, like the one at our local dealer, did nothing to help and in fact returned my unit in worse condition that when they received it.

TROUBLESHOOTING TIPS:

If you can hear "click, click, click" and smell propane exhaust, then your sail switch, controller and gas solenoid valve are ALL WORKING. Otherwise there would be no click and no propane injection happening.

In this case, it could be low propane, low pressure, or a misaligned or dirty electrode. Try the throttling trick, but only once or twice. Dont tape over the outside air intake, just use the palm of your hand to half cover it and see if you can get it to fire.

If it fires up when "choked", then try to figure out if you have low fuel, low pressure or if it is the electrode. It's a process of elimination.

By the way, if Dinosaur Electronics makes an OEM replacement board for most Suburban and some other brands of RV furnaces, and they are worth the money. They are pretty easy to install (other than access issues to the back side of the furnace) and they offer 5 tries/5 strikes (5 clicks) rather the standard 3 strike (3 clicks) on the Suburban OEM board. This can make a difference if your furnace is cranky on startup.

I also suggest firing up the furnace EVERY TIME YOU GO CAMPING, even in the summertime, if just for 5 minutes. Blow the dust out of the unit and make sure it runs. You'll be glad when winter rolls back around.

[walk_the_walk]

Originally Posted by Webgypsy

...Pulling the entire unit is unfeasible alone.

So far I have:
*Dealer replaced three times but never reported failures to Suburban so they told me to fly a kite.
* Dealer replaced sail switch and never reported to Suburban
* Dealer replaced PC board and never reported to Suburban
* Dealer replaced limit switch and may have reported to Suburban
Dealer's technician walked away, said it was repaired and I went another winter with no heat.
* I found that the igniter was too far from incoming propane so I took it apart and bent it down and it started lighting
* Runs 5 minutes and shuts down. Wait ten minutes, play with thermostat and it might come back on.
*I replaced limit switch and thermostat quit working
*I replaced thermostat with exact Coleman-Mach model
*Heater now lights and warms. While running it randomly clicks as if it is trying to light again. It shuts off long before room temperature is up and will stay off unless I wait ten minutes and play with the thermostat.

I have concluded I am unable to fix this myself. Do I choose the person that says you should not bench test the heater and only work on it in the RV or do I hire the guy that says he will pull it and bench test it?

***********

What is the model of furnace?
Have you asked the manufacturer what they think the problem might be?
I see no advantage to pulling the unit and taking it to the dealer. Mine worked fine at the dealer; they took it apart, charged me, gave it back and on reinstall, it squeaked like a rusty gate, so we had to uninstall, realign the plastic fan housing and re-install. If that is what bench testing is about, I want no part of it. Also, there are several problems that cannot be detected by a bench test (such as faulty pressure regulator, low fuel, leaky or poor duct connection inside the trailer, loose wire connection where furnace ties into trailer power/thermostat wiring, just to name a few). Put another way, NONE of those problems can be identified by a bench test.

Shame on your dealer. I would hire a recommend mobile RV repair person (check Angies List or ask around) and pay him to fix it. That said, you might want to replace the propane regulator first, since they only cost $35-$50 and can be replaced with an adjustable crescent wrench. Or buy one on Amazon and have it handy for the mobile guy to use. The one we bought that is made in Italy which is quite nice is the Cavagna Auto changeover regulator, (model 52-A-890-0006C) which sells for $43 on Amazon. CAMCO makes a plain jane version, also sold on Amazon. If your furnace is a Suburban, you can also buy the sail switch, gasket and electrode on Amazon now, which is handy, as you can return them if unopened and unused.

Sounds like you spent some money doing "shotgun troubleshooting", as we all do when learning how to fix these damnable furnaces (for example replacing the thermostat probably was not needed). You still have a problem, though, based on your description, if the unit runs for a bit and HEATS, then stops and starts clicking. The furnace is going out and attempting to restart.

Off the top of my head this sounds like any of these possibilities:
1. Sail switch or limit switch (something is causing the gas solenoid to shut off after all)
2. Leaky duct work attachment that is causing the sail switch to not stay closed?
3. Bad gas/propane solenoid
4. Bad controller board (unlikely though, given your description)
5. Low gas pressure

Given what you describe, the mobile repair is your best bet. It's probably something tricky, but a mobile RV guy will have the experience to know how to troubleshoot it.

Please post back when its fixed to let us know.

[StorminNorm]

Thanks for the above detailed posting. I read it twice before I pulled my gas heater in my 2006 Cherokee trailer. The heater has gotten increasingly noisy and rattles a lot which wakes the occupants of the trailer (me) when it is running.
It took me about 1 hour to pull the heater out, finding it refuses to pull out until you remove the outside vent covers. Sure enough a hold down bolt was missing on the fan unit (factory hole was there but never bolted). I installed a small bolt with locktite, then reassembled it. It took 15 minutes to reinstall. A final test proved it was much quieter now. I still had to install chunks of pool noodle (plastic foam) to keep the outside enclosure from rattling too loudly.
I found the wiring had marr connectors on them and these were easily reachable so I am not sure why you needed auto connectors on the wiring. I also vacuumed out about a 1/4 cup of metal filings from the compartment from the original trailer manufacturing.
I was ready to buy a new heater to stop the rattle but am happy with the results I got. Thanks to the original post I was confident enough to pull the unit out. I also noted that there was no way to pull the fridge out and work on the heater as the cabinet is solid wood and I would have had to saw through to get to the heater, not a great option.

[walk_the_walk]

Congratulations. You have completed your on the job training and are now officially certified as a Dometic RV gas furnace repair technician.

******

As to your question, there are connectors on the main board. It's been a while and I don't recall if all four wires had a connector, but I do recall that we could neither see nor reach the connectors from the tiny access space beneath our Dometic refrigerator. Luckily, we had a cheesy thin fake wood panel that we could remove to get near the business side of our Dometic SF-30 furnace.

Glad your repair went so well. The missing screw/bolt sounds like a Dometic QC issue. They are based in Tennessee were quite helpful when I called them with questions, BTW.