Don't waste your money on those little propane tanks. They are damn near always underfilled when you swap them out and they waste ALOT of gas when the tanks start freezing up during heavy sustained use. I have a lot of experience with the gas cylinders and high pressure tanks. All gas is under pressure will cause a drop in temperature when you're releasing that pressure. But with a liquefied gas such as propane the expansion occurs inside the bottle in the volume of space above the liquid. With small tanks they don't have alot of mass so it will drop its temperature very quickly. When that happens the amount of gas you're using when it's cold even though it might be the same PSI is much different than when it's warm. It's like when you fill your tires up in the summertime and then come winter time the PSI drops because it's colder. It's the same thing with this when the tanks are cold you're actually running through gas sooner because it takes up less volume when it's cold exiting the bottle then it does if it were warm like around summertime or if you had the bottle sitting in a warm water bath. Call up your local welding supply or high pressure cylinder supplier (not the big name brand companies because they are usually more expensive) and order the 100lb propane cylinders. The difference is night and day as far as the use and how much longer they will last. You can decide if you want to purchase one of the 100-pounders and then just have them fill it or you can even do rental where they'll charge either a deposit fee or a monthly rental of something like $5. In the end it's much cheaper to buy it in bulk like that than it is with a little ones.