When I bought the trailer, the PO said "oh, we never used the furnace", which everyone knows is "weasel speak" for "the furnace
is broken but I don't want to tell you that". There was clear evidence that the furnace
had been used since the brass handle on the shutoff valve was not as tarnished as the rest of the valve, and the pilot 'reset' button was nice and shiny where one would put their finger... I persisted and managed to get the pilot lit pre-sale. But it took darn near 30 minutes to do. The pilot just wasn't catching or when it did, was a tiny limp flame.
Our first camping trip, the furnace
performed admirably after spending 30+ minutes trying to get the pilot to light
and stay lit. Good thing too, because it snowed that night.
Second camping trip I got the pilot to light
after much persistance but unbeknownst to me, it went out early in the night and we had a chilly (but not uncomfortable sleep)...
Last camping trip, I could not get it to light
_at_all_... No way, no how...
We're going next week, it's starting to get cooler at night in the mountains, so I wanted to make sure we had the option of heat, if we need it.
So I removed the furnace from the trailer, stuck it up on my workbench, pulled it out of its sheet metal shroud, and started analysing... I confirmed the thermocouple was good because I could heat it up with my lighter and hear clicking both on the heat-up and cool-down... I grabbed my old and spare Boler propane
regulator and along with some other fittings, hooked a 20lb propane
tank up to the furnace on my workbench. I removed the pilot 'tube' from the "controller" at the back of the furnace, pushed the pilot reset button, and heard the comfortable hiss of propane
... So I worked forward toward the pilot orifice. There was no cloggage in the tube as it entered the pilot orifice so I concluded the pilot orifice was clogged. I removed it and looked, and could see where there should be a teeny tiny hole, but the hole seemed plugged... I couldn't find a pin or anything small enough to fit in the hole, so figured I'd have to buy a new orifice. On a lark, I threw it in my ultrasonic washer with some brakleen (dry cleaning fluid) for 15 minutes... After I took it out and dried it off, I was able to look through the orifice and a few photons got through the hole to my retina...
Reassembled the furnace and voila! The pilot lights
This was surprisingly little effort overall. I don't know if these orifices (orifii?) are common off the shelf items or not.