Probaly coming from being bored on a Sunday afternoon,,,
A couple of numbers regarding capacity and consumption of the westy l/p system.
(Please correct me if I have made errors in either my assumptions or my calcs.)
The Westy Propane tank holds 3 gallons of propane. Properly filled to 80% means a useable fill of about 2.4 gallons. A gallon of propane has 91,690 btu's available for a on board capacity of 220,056 btu's.
I have searched for the btu input capacity for the stove and fridge, can't find them, and not wanting to pull my units just for fun I'll make a couple of guesses. I would think that each stove burner would be lucky to put out 15k btu/hr. I would guess that the fridge on full bore would use 500. (The flame is smaller than a bernz-a-matic torch flame, and it runs hours on a throw away tank.)Update 6/15/07 I ran across a late model vanagon fridge and on the door there was a placard stating the fridge use 360 BTU/hour, so I was close!)
So if you use the stove 2 burner hours a day at half flame, (15,000btu) burn the fridge 18hours a day (9,000) you should be able to go better than 9 days on a full tank.
My own experiance tells me that these estimates are very conservative, the fridge will cycle to low flame, running on 12vts while underway, 2 hours of burners is a long time etc. Unless you are going to the real boonies where you go more than ten days without being able to get propane, it seems to make little sense to either carry or add on a second tank.
When you think about it, how often do you have to fill your bbq tank? (4 gallons @80%/366370btu) Most bbqs burn up to 35,000btu's per burner. I go through a bbq tank a year or so.
Icarus