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chimmeysweep · 02-10-2020, 09:25 AM

My 2011 Winnebago Adventure LP heater does not operate above 4800 ft. Went to Mammoth Mountain in California (7200 ft) and froze my huevos off. Opened up compartment where the LP heater is in the back under sink and sure enough there is a sticker on top of furnace that says basically this heater is good only from 0-4800 ft elevation. Someone had mentioned something about jumpering the seal switch or sail switch. Any thoughts or know of anyone in Southern California Los Angeles Area that can do that for me?

Jim_HiTek · 02-10-2020, 09:35 AM

Maybe things are different on vehicles of the 2011 vintage but there use to be an adjustment for high elevation. Check your users guide for yours. Then armed with that knowledge, try to find a local Mobile RV Service or a handyman to do the work for you.

SteveJ. · 02-10-2020, 10:00 AM

Quote:

Originally Posted by chimmeysweep

My 2011 Winnebago Adventure LP heater does not operate above 4800 ft. Went to Mammoth Mountain in California (7200 ft) and froze my huevos off. Opened up compartment where the LP heater is in the back under sink and sure enough there is a sticker on top of furnace that says basically this heater is good only from 0-4800 ft elevation. Someone had mentioned something about jumpering the seal switch or sail switch. Any thoughts or know of anyone in Southern California Los Angeles Area that can do that for me?

The furnace may have a partial air blockage in the intake or exhaust that would inhibit the flow just enough that in thinner air there is not enough air pressure to engage the sail switch. I don't know what brand of furnace you have but the 20 year old 16k btu Suburban that I have works just fine up to 10,000 feet.

I would try looking for an obstruction. A furnace that only works below 4800' seems kind of worthless in the high country out west.

Mark_K5LXP · 02-10-2020, 12:54 PM

I don't think defeating the sail switch is a very good idea. In the event a duct is blocked or there's a blower problem the burner will still activate and cook away. If it's actually the sail switch not having enough air velocity maybe there's a different blower cage or motor to use. If it's burner related I'd be looking at seeing if there's a burner air adjustment like on water heaters, or maybe there's an optional gas orifice you need to install like for S&B furnaces at altitude. There are enough RV furnaces that work just fine at altitude to show that it's possible, you just need to figure out what yours needs to do that.

Mark B.
Albuquerque, NM

gatorb8 · 02-10-2020, 01:20 PM

if the sticker says it's only good to 4800', defeating that spec may be hazerdous

SteveJ. · 02-10-2020, 01:29 PM

Quote:

Originally Posted by gatorb8

if the sticker says it's only good to 4800', defeating that spec may be hazerdous

^This.

I would not do anything to defeat a safety system. But I think it would be prudent to check for a partial obstruction. Mud daubers and other small critters love furnaces. Again, this would be for the outside intake and exhaust for the burner, not the duct work that's part of the air handling system.