need help calculating propane usage.

[Off Grid Rving]

Hello guys, I know that its possible to get a rough calculation going of how much propane I will use with my system.

I have 48sq feet at 6x8 floor space in here by 6ft 2in tall at the highest point. so we will use those numbers for figuring the air space.

=297

the heater is a pro com 10,000 btu heater with thermostat. hooked with a two stage regulator to a 20lb propane bottle.

the insulation value is r 7-8 walls.

what is a rough est that the propane bottle will last on a single refill?
other variables, keeping temp at 69ish

[suitcase_sally]

From my experience, about a week. Is this a deer blind? One variable you have to consider is, what is the outside temp? In southern Wisconsin I would say in the 30's?

[TnAndy]

You're missing part of the info.

You have to know heat loss in order to know how many BTU's the heater needs to supply to keep the inside 69ish.

To calculate heat loss, you supply the OUTSIDE temps....either average or use degree days.

[TnAndy]

(Building Heat Loss in BTU's per hour) =

(Building Total Surface Area in sq.ft.) / (Surface Area "R" value)] x (Temperature Difference)

Temperature difference being 69ish - outside temp.

Once you know how many BTU/hr your room looses, you can divide that into 21,591BTU/pound that propane contains, and get a rough idea how long one pound will last....then x 20 for a 20lb bottle.

Two notes:

This doesn't take into account wind, which can have a significant effect on heat loss.

And it assumes your heater is 100% efficient, which most of the small, unvented propane models get close to.

Happy calculating !

[Off Grid Rving]

I need to get started on my solar pop can air heater to do all the day time heating. save gas for nights.

its going to be fun making it through winter. but this project is already very satisfying. www.offgridrving.com