Has anything like this happened in the past? Sounds to me like you got a loose or mispositioned part in the gas stream between the control valve and burner, or the burner itself is not secured properly, and is causing a rich burn.
OK, wait...speaking from experience here as I had this happen earlier this summer...there is one other very strong possibility...if your propane tank's OPD (over-fill protection device) malfunctioned when the tank was filled and the technician wasn't paying attention when he/she filled the tank, the tank could be over-full, and is allowing a mix of liquid and vapor to enter the gas regulator...this will cause flare-ups with a sooty orange flame, and the regulator will likely develop frost on the exterior (from sub-freezing temp)...that's your sign of liquid going through the regulator. Tip the tank side to side and see if you can feel some liquid slosh...if there is little to no slosh, it's over-full. You can fire it up and leave the door open with the flame on high for 5-10 minutes and see what happens...if you get a flare-up after a few minutes, an over-full tank is probably the cause. If you use enough LPG from the tank to resolve this, operation should return to normal...it may take an hour or more to use enough fuel to create enough vapor space in the tank to allow for boil-off of liquid without liquid exiting the valve. BTW, this can happen to tanks of any age, and certain brands of tanks are more susceptible than others. I have had 2 faulty tanks so far from Sam's Club, purchased in the past 3 years or so...one had an excess-flow valve issue and the other was a faulty OPD, causing the above described issue. If your tank is from them, knowing what I know now, I would automatically be suspecting a faulty OPD in the tank.
Eric
