Refrigerators in the heat

LP and 120 have almost the EXACT same BTU affect on the Burner flue. BUT, what does affect operation on 120 is the LINE VOLTAGE. IF your supply 120 voltage is below 112 volts, then the 120 operation will not be as good as LP. LOWER line voltage, LESS heat is produced by the 120 heat element. Unless your LP system PSI is not at spec(very rare), the LP will have a consistent heat that will heat at optimum for cooling. Now, the variable on LP would happen above 5 or 6 thousand feet in the mountains. Then 120 would be the logical choice for better cooling.
1. ABOVE 112 volts go with 120
2. BELOW 112 volts, go with LP.
Remember, the LP flame ALONE does NOT heat correctly. It takes the SPIRAL BAFFLE installed in the burner tube to evenly distribute the heat from the flame to correctly heat the FLUE tube. Doug

Propane.

PP should be a bit more powerfull.

I usually go for LP, simply because everyone is using electricity to keep cool, and normally the power is strained. Plus I have a theory that the added heat of the flame aids in convection, though a lot of units use fans, which cancels out that advantage.

These posts address that;

gas or electric 1

gas or electric 2