www.all-cordless.com

Propane Vaporization Rate Information
Have you heard about the guy's that have a 250,000 Btu heater and runs it on a 20 lb. propane tank and it works great. We have also heard that many times and we also know that it does not work great.
For Maximum Operation Due to the pressure in the propane tanks, many of our heaters require a 100 lb. tank or larger to operate. Propane tanks that are less than 100 lbs. do not have much pressure. The propane ends up freezing in the pipes, which ruins the heater and voids your warranty. We recommend that all of our customers use a 100 lb. tank or larger unless the heater description tells you otherwise.
Rule of thumb for heater tank sizing is: 75,000 BTU heater needs minimum of one 100 lb tank, 150,000 BTU heater needs two tanks manifold together and so on. A 250,000 Btu heater will not work great with a 100 lb. tank. It will operate, but a 100 lb. tank will only give you 167,000 Btu @ 20 degree F, so don't think your 250,000 Btu heater is running properly even on a 100 lb. tank. At 20 degree F, you should manifold at least three 100 lb. tanks for maximum output.
Tank sizing for heaters is very hard to understand if you are not familiar with it. To make it a little easier to understand, just figure 75,000 Btu per 100 lb. tank. So if you have a 150,000 Btu heater, you should use two 100 lb. tanks manifold together. If you have a FULL 20 lb. tank and want to run a heater, the largest heater you can run properly at 20 degrees F is 45,000 Btu's.
You only get 113,000 Btu when the 100 lb. tank is full. When the tank is at 50% full you get 64,000 Btu. When you have a heater that seems to be working great, but you can not feel much heat, it is because the tank is low on fuel. You can sometimes tell by looking at the tanks frost line.
Hose Sizing For high pressure heaters that use 1/4" hose, you can use 1/4" hose up to 25 ft, you should use all 3/8" hose up to 75 ft, you should use all 1/2" hose from 100 to 150 ft. For low pressure heaters that use 3/8" hose, use 3/8" up to 50 ft, and use 1/2" for 75 ft to 150 ft. for low pressure Natural Gas Heaters 150k and smaller, use 1/2" hose up to 50 ft, 3/4" hose up to 150 ft.
LP Conversion

8.547 cu. ft. per pound

4.24 lbs. in gallon

36.45 cu. ft. per gallon