Propane Vaporization Rate Information
Have you heard about the guy's that have a 250,000 Btu heater and runs it on a 20# 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
Rule of thumb for heater tank sizing is, 75,000 BTU heater needs minimum of one 100 lb tank, 150,000 BTU heater need two tanks manifold together and so on. A 250,000 Btu heater will not work great with a 100# tank. It will operate, but a 100# 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# tank. At 20 degree F, you should manifold at least three 100# 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# tank. So if you have a 150,000 Btu heater, you should use two 100# tanks manifold together. If you have a FULL 20# tank and want to run a heater, the largest heater you can run properly at 20 degrees F is 45,000 Btu's.

As you see in the chart below, at 0 degree F, you only get 113,000 Btu when the 100# 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.

Vaporization Rate
100 LB Propane Cylinders (approximate)
Maximum Continuous Draw In BTU Per Hour At Various Temperatures In Degrees F.
Lbs. of Propane in Cylinder 0 degree F
1 Tank		 20 degree F
1 Tank		 0 degree F
2 Tanks		 20 degree F
2 Tanks		 0 degree F
3 Tanks		 20 degree F
3 Tanks
100 113,000 167,000 248,000 367,000 545,000 807,000
90 104,000 152,000 228,000 334,000 501,000 734,000
80 94,000 137,000 206,000 301,000 400,000 662,000
70 83,000 122,000 182,000 268,000 363,000 589,000
60 75,000 109,000 165,000 239,000 310,000 453,000
50 64,000 94,000 141,000 206,000 260,000 382,000
40 55,000 79,000 121,000 174,000 217,000 319,000
30 45,000 66,000 99,000 145,000 217,000 319,000
20 36,000 51,000 79,000 112,000 174,000 246,000
10 28,000 38,000 62,000 84,000 136,000 184,000
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.
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LP Conversion
8.547 cu. ft. per pound
4.24 lbs. in gallon
36.45 cu. ft. per gallon
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