Using inverter for Fridge at high Altitude

[Skyliner]

Couple of other suggestions:

1. Manually start the fire for the fridge I do occasionally have problems igniting propane with spark generators especially my stove top and use a small pen butane torch to light those off. I'd say most folks have a problem with their propane fridges igniting and they then usually do OK once the fire is burning. If you can, try to ignite the propane manually once you got to your high altitude camping site if your self ignition system doesn't do the trick.

2. Another option: Remove the orifice and then seal the orifice hole with 100% silver solder (use a lot of flux at first). Then using an orifice drill bit, drill out the orifice carefully with a drill bit one size smaller (increase drill bit size by 1 ..example if hole is a #56 then use a #57 bit (smaller drill bit) and that should do the trick. As you go up in drill big size, you get a smaller diameter bit and vice versa.

I haven't done this to any of my propane devices but I have rejetted my generators and other engines with this method without any problem other than some trial and error since gas engines mixture settings are more precise. If you screw up and drill too big of a hole, just resolder it and try again. VERY EASY to do. When you come back down in altitude, you can either drill it out or just buy a correctly sized spare for sea level.

[Skyliner]

Ok,did some math by looking at drill but numbers, their associated diameters, and reduction in surface area.

Going from a #56 diameter orifice hole to a smaller #57 diameter orifice hole after soldering it shut and re drilling reduces the area of the "hole" by approximately 15%. If this is enough depends on many variables but should be a close starting point. Many stock fridges run just as fine at high altitude without changing orifice size. Its possible that your fridge just needs a minor tweak. If this doesn't fix starting or running, then by all means try the next smaller size thereafter.

As a pilot, we use a general rule of thumb for 3% less power output of an engine due to thinner air with every 1000 foot gain of altitude...a simple approximate rule of thumb that doesn't take into account air temperature/density. If you are camping up to 8,000 feet, going one drill bit size smaller in orifice diameter may not be enough and perhaps 2 drill bit sizes would be better.

I'll let you decide what diameter to use if you are concerned. I checked my Dometics and Norcolds at the top of a 12,127 foot pass and both started up and run fine at those altitude and BOTH WERE STOCK. I think you'll be ok with one diameter smaller size but going 2 smaller sizes if you camping at 8500 ft and higher wouldn't hurt.

Buying spare orifices is not very cheap but I'd rather spend 60 bucks on 2 orifices to have easy to replace options at higher altitudes. I'd have stock size for sea-level to 4000 feet, one size smaller orifice by soldering and drilling for 4000-8000 feet, and orifice soldered and drilled 2 sizes smaller for 7000 to 1200 feet.