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Old 10-05-2012, 03:17 PM   #1
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1973 31' Excella 500
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Pilot flame too small

I have a Suburban NT 32 A furnace that I assume is original to the '73 AS. I've never used it but thought I would inspect and repair or replace for possible use this winter. The only problem I've encountered thus far is that the pilot light is very small and not enough to warm the thermocouple. I've disassembled, inspected, and reassenbled the LP supply including the manual valve, and the pilot adjustment valve. I see no reason why the pilot would be starved for fuel.

One thing that seems counterintuitive is that were the supply tube has a closed end 1/4" before the flare shape that holds the flame. It was manufactured that way. I don't know how any LP gets through but a little does, just not enough.

Any thoughts?
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Old 10-05-2012, 03:42 PM   #2
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...The only problem I've encountered thus far is that the pilot light is very small and not enough to warm the thermocouple. I've disassembled, inspected, and reassenbled .... I see no reason why the pilot would be starved for fuel...Any thoughts?
Most sane people replace furnaces that old. In the interest of safety, replacing your furnace is what 93% of the world will most likely recommend.

But if you have both a smoke/CO detector and a lick of common sense, I recommend you clean debris out of the pilot jet assembly like I do every 3.2 years and save your money.

I'm hoping for a cold-weather trip to Cloudland Canyon to cap 2012 where my '67 Overlander's original furnace will supplement the campfire if needed.

Tom
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Old 10-05-2012, 05:15 PM   #3
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Also check your LP pressure at the furnace, it should be around 11" water column on a gage which I believe is about 2lbs. If it is low the regulator can be adjusted.
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Old 10-05-2012, 05:32 PM   #4
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I haven't measured it but all other appliances burn well.

I still find it odd that the supply tube for the pilot looks like it has a plug in it.
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Old 10-05-2012, 06:18 PM   #5
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I still find it odd that the supply tube for the pilot looks like it has a plug in it.
So replace it. That tube screws into the valve, simple to replace if it's anything like mine. So is the thermocouple, for that matter. You can get the pair of them for something less than $50.
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Old 10-05-2012, 07:32 PM   #6
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I just got back from the local RV store. They looked at the "plug" and said that they had seen that before. They couldn't explain how it would still work but that the replacement would be the same.

I don't understand the plug but I'm going to consider it to not be the problem for now.

I'm thinking maybe a faulty Basotrol valve that isn't letting enough LP through when being when the thermocouple is being overridden (or perhaps or perhaps at any time).

Does a faulty Basotrol valve sound likely?
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Old 10-05-2012, 08:21 PM   #7
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The Suburban you have uses a very tiny pilot orifice with two even smaller holes in it. They are so small that even held up to the light and looking directly on, you may no see through and find them. I would guess that one of the two holes is plugged up

You may find it hard to get a pilot orifice for the furnace. Suburban has discontinued all support for all the older pilot model furnaces. The last time I tried to get one my parts dealer found some NOS at his distributor. You may or may not have the same luck.

It is very difficult, if not impossible to clean the pilot orfice.

Best of luck.
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Old 10-05-2012, 09:06 PM   #8
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It is very difficult, if not impossible to clean the pilot orfice.

Best of luck.
It was told to me on more than one occasion that they are fairly generic. The same people agreed that cleaning them isn't for amateurs, and pros would replace.

However, I suppose it's possible that this one is unique. But if they are available, like I said above, both the pilot and the thermocouple are relatively cheap to replace, and could not be easier to do.
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Old 10-06-2012, 01:42 AM   #9
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Nothing in the store looked even close to being a direct replacement. They are going to call a supplier on Monday to see if they can get the correct part. I'm considering the valve to be the more likely culprit tho.
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