1987 Excella Suburban Heater help

[southsaglejim]

I have a 1987 Excella 32 ft with the original Suburban NT 30S heater. It is located under the original Magic Chef oven. Recent repairs had it working.

Now when I activate the thermostat all goes well until ignition. Ignition happens and the propane lights but only for about 1 second then the flame goes out. Any educated guesses as to what might be my problem?

It is my understanding the NT S30 configuration is no longer available. Am I correct?

A new heater would require drilling new intake and exhaust holes in the aluminum skins which I prefer not to do. And I do not want to address cabinetry issues nor rerouting duct work.

In other words, I want to fix what I have. Can it be done?

[Bill M.]

We have a 1987 32 foot also. I have heard tales of igniters not being available and the need to change the intakes. Have seen a trailer that was done to.

We have a good, reliable mobile rv repair service where we keep the trailer in Florida. They came and pulled the heater and ran it in the back of their service truck that has propane and 12 volt. They got it working fine. They put it back in the trailer and it did not work. Gas flow meter showed that it was not getting enough gas. So they changed the regulator. Still did not get enough gas. So..they found that the rubber hose that connects the copper lines to the regulator had failed internally and was partially blocking the gas flow. A new line there and everything was fixed and it works now. Good luck with yours.

[richard5933]

There are a couple of other threads about this, so a search might find you some help. One thing mentioned was to confirm that your regulator is working correctly and supplying the proper pressure. Wouldn't hurt to verify that you have fuel and/or that the switchover mechanism is working.

If the basic components are solid and not rusted through, you should be able to get the furnace repaired. I had a similar furnace from that series in our vintage coach. It took minor surgery, but I was able to get it running again and avoided having to make the kind of modifications you described.

[Wazbro]

The main thing to worry about is the fire box rusting through. That can't be replaced and is dangerous (CO poisoning).

[Buckless]

May not be the problem but make sure no dust or debree is on pilot light Then the thermocouple must be in the flame.

[Turbine]

We also have had to spend quality time recently with our Suburban NT-30K in a late 80s Excella. Like you, I refuse to cut up a decent trailer for the sole purpose of making something that was not designed for it somehow worth the time and expense.
Some thoughts, referrals, and one piece of important advice:
· Suburban told me they no longer manufacturethe NT-30 series.
· There seem to be NOS and serviceable-as-removed units for sale on various platforms, including this one. Most know what they have, and are priced accordingly. Be hyper-vigilant to protect yourself from fraud and scammers.
· Used parts also seem to be readily available from numerous internet sources, if you know exactly what part (i.e. part number) you need.
· The electronic ignition board is generic and readily available at reasonable pricing. PM if you need specifics.
· Honor the high quality troubleshooting advice on previous posts to this thread. Start with the simple stuff first, to include the serviceability of the thermostat. My experience has been the furnace is a decent design that facilitates a full teardown if necessary, well built with decent quality materials, and in general is worth the effort to maintain and repair when necessary.
· One important piece of advice (IMHO): if the furnace is removed for repairs or maintenance, start by CLOSELY inspecting the firebox for perforation or impending burn-through even though this item is not generally a flaw in the design or manufacture. It is simply a common sense safety check easily performed. No point in even beginning to resurrect a malfunctioning unit if the firebox is unservicable. The firebox can be patched, but I wouldn’t let anyone who hasn’t done it before use your stuff as a learning exercise.
Best wishes for solving your maintenance problem before the winds turn cold.

[lemley]

I have an ‘88 29’. Have had several issues with the furnace over time. Got to know the operation sequence like the back of my hand.

At the point in startup you are describing, the board is looking for heat to see that there is good flame and to leave the propane solenoid active.

So I’d look at three things:
Propane flow (hoses, regulator, crushed pipe)
Thermocouple. Positioning can be critical. And the thermocouple can go bad. It’s pretty easy to replace.
Control board. I never had a failure there.

Finally got to the point where every trip was a crap shoot. I bought a new furnace off of a wrecked new unit on eBay. There is a seller specializing in these units. These furnaces are dirt cheap, but buyer beware. Some are in good shape and some are pretty badly mangled. The info is in the postings but look at the pics carefully. There are several different geometries- vertical or horizontal mounting, dimensions, propane hookup inboard or outboard. But there are none with three vents. I added a 1/8” plate to cover things up. It looks like a cover. That covered the old holes and allowed me to put the new holes in precisely the right location. Connecting the ducts was straightforward except for one vent 1” from the cabinet wall. That took a little furniture carving but allowed me to change the propane detector mounting to the new geometry. I’m happy with the result. DW is glad the heat comes on EVERY time.