I see a lot of folks having various problems with low heat output on occasion. Here are several easily correctable situations.
1) A very full tank. Usually happens when you take a tank to be filled, not from the exchange places. Shut the tank off and unhook regulator. Then take something like a PLASTIC cheap Bic pen and push in on the center of the tank connector. It is a spring-loaded safety valve. I have found an extreme pressure build-up that will actually trip the excess flow check in the regulator. It will give a small gas escape. Reconnect the regulator.
2) Remember to turn on the tank slowly before the appliance. If you do the reverse, the excess flow check valve in the regulator can be triggered. Then you get almost no propane out.
3) Regulator icing or frosting up. Rare but can happen. Warm, moist cloth wrapped on regulator will thaw it out.
4)Also if you haven't used your burner in a while.... and especially in the spring, check your venturi for spider webs. Just run a pipe cleaner through the venturi to make sure it is clear. I would find a spider had nested in it over the winter and the spider silk would completely block the path.
5) When lighting a burner open the tank first, only about an 1/8th of a turn. Turn on the burner next and light. Then open the tank valve a bit more. Most of these small burners take very little gas flow. Turning the tank on full can sometimes cause enough flow throw the regulator and empty fuel hose to trip the excess flow safety valve!! Especially with a brand new tank fill.
I have found that the tank "burp" and making sure to open the tank before the appliance usually corrects the excess flow problem. My local propane source is proud of giving a full tank. They make sure you get your money's worth. And no, not unsafely. They do leave the correct safety margin. So sometimes the burp is needed. Most exchange tank places are actually a bit underfilled so they do not encounter problems. I have weighed them and find only 18-19 pounds on a supposed 20 pound fill.
#4 Added to list - thanks JIRodriguez for reminding me.
Edited by lonestarmedic - 5/11/15 at 7:35am