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Old 08-06-2012, 04:19 PM   #1
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1977 23' Safari
Hutchinson , Minnesota
Join Date: May 2012
Posts: 7
Suburban furnace primary air problem

Hi Folk! In checking out the furnace on our new to us 1977 23' Safari, I noticed that the flame was very yellow/orange. I adjusted the rod that is supposed to control the primary air throughout its range of 18 revolutions with no affect on the flame. I am wondering if it is common for some critter to get inside and build a nest or somehow plug up the air flow. If anyone has had a similar problem, please advise.


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Old 08-06-2012, 04:51 PM   #2
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2008 25' Safari FB SE
Grand Junction , Colorado
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I haven't had that problem, but I have read critters such as paper wasps (mud daubers) like propane (more likely they like the odorant) will build nests in there. If you see them flying around there and one eventually goes through the louvers, that is the answer.

I would, if they are there, spray some wasp spray in there and leave the area because they may get angry. They are usually pretty mellow until disturbed. I know that from experience with a nest I didn't see when I went to clean a basement window. A few followed me to the door and their stings can be pretty painful if they get a good one.

Come back the next day and vacuum out the area. Then use a long screwdriver and poke around to break up the nest and vacuum again. You may see some flying around even then looking for their home.

You can buy a mesh cover for the opening at an RV store that will keep them out.

If that is not the problem, the adjustment may be worn and not doing anything. It could be rusted out or just worn.


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Old 08-06-2012, 07:11 PM   #3
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1955 22' Flying Cloud
mapleton , Utah
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Another thing to check is the pressure in your propane supply, especially if you have an old/original regulator. The color flame you describe seems pretty lean. opening the valve on the flame adjustment wont have much effect without proper pressure and flow rates. Be very sure that you dont have insect nests or webs in the burner or vent assemblies. Can cause carbon momoxide increase along with other more obvious issues. If possible, removal and bench testing might be safer.
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Old 08-06-2012, 07:35 PM   #4
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2014 20' Flying Cloud
Kooskia , Idaho
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On a furnace your age there is a cast iron burner which can become rust clogged. So, if it is not insect nests which are causing the problem, most likely you will need to clean the main burner. This requires a major disassembly of the furnace but it can be done and will work wonders on your problem.

See photos and you will understand what the problem is and how to fix it.
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Old 08-07-2012, 12:48 PM   #5
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1977 23' Safari
Hutchinson , Minnesota
Join Date: May 2012
Posts: 7
Ok, Thanks for your input. It seems likely that I have either rust or some other obstruction which is keeping my primary air restricted. Another problem could be that I am using up a tank of propane that still has the old style regulator, so that too could be a problem. The gas guy told me to use up the gas and them bring it in to be changed over. We already did one which I will switch over to to test that theory out before I pull the burner. Right now "The Toaster" is sitting at my nephews until Saturday when we will put on her new axles, brakes, shocks and Centramatics. We are supposed to leave Minnesota for Montana and Utah in one week. Our TV is in getting the transmission fixed (an ongoing problem) and we are hoping the axle replacement goes through "without a hitch" so to speak. Again, thanks so much for your valuable and appreciated input. I will keep you posted when I determine the culprit.

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Old 08-07-2012, 01:00 PM   #6
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2002 25' Safari
Dewey , Arizona
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It sounds like your propane tanks need to be upgraded with the opd (overfill protection devise) valves. This upgrade was mandated by law and took effect over 10 years ago. This upgrade should have no effect on the performance of your furnace.


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Old 08-07-2012, 03:26 PM   #7
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1968 24' Tradewind
Oxford, , Mississippi
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My older model Suburban (NT-22) had issues. I never could get the proper blue flame. I took it to a buddy in the HVAC business (took him a propane tank and 12 V battery). He called me a couple of days later and said he had found a hole in the heat exchanger. That could have been deadly. It was rusty and years of neglect had taken its toll. This may not be an issue with your furnace but I wanted to post this experience again so folks with older heaters would be aware of potential hidden dangers in the old Suburban furnaces ( in addition to the well documented problem with the cross-over tube).
Bruce & Rachel
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2001 Toyota Tundra
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Old 08-07-2012, 06:50 PM   #8
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1955 22' Flying Cloud
mapleton , Utah
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Cabinrat, dont confuse your regulator with your fill valve. the valve is semi-permanently connected to your tank and as previously stated needs to be of the OPD type, sounds like you already had one of these changed. The regulator which is the part connected to the hose is removed for each filling and controls the volume and pressure supplied to your system.

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