On Thu, 20 Sep 2018 22:51:29 -0400, Ed Pawlowski wrote

It can be calculated and I may still have the formula. You have to know
the output of the burner and you can figure how long it will burn on a
tank of propane.

Gallon of propane has 91,000 BTU. Water heater is about 30 - 40,000 BTU

A BTU is the energy required to raise a pound of water 1 degree. Gallon
of water is 8.3 pounds. to raise it from 70 to 120 takes 50 x 8.3 x how
many gallons you used.

Good news. I thought I was at zero percent but I actually have 5 percent.


I think that means I have about 15 gallons, which may last long enough for
the road repairs to be made (they're scheduled to finish by November 1st).

The hot water heater says its inlet is 37,000 BTUs, right where you said it
would be.