Be sure to turn on the propane tank(s) very slowly, so the safety valve doesn't close. Since this sounds like it's the first time running,
it will probably take a few times before it fires up. The blower will run for several seconds first. If the propane hasn't reached the furnace yet, it'll shut off. Turn the thermostat off, then back on to start the next cycle. You'll hear the burner when it finally lights.
Every day's a learning experience, though sometimes not what we expected.
2012 Jay Flight 19RD
2016 Ford F150 XLT 2X4 SC 3.5L Eco Max Tow
2010 Tundra TRD DBL Cab (Traded)
2 new fluffy Corgis, Bayley and Stanley