Question: I have installed a Heatilator Novus direct vent fireplace with a standing pilot. The pilot light can be lit and will stay lit, but when I turn on burner things go bad. The burner will always light, then after about 1-1/2 minutes or so, the burner will shut off. Sometimes the burner will re-ignite itself after about 5 minutes and the cycle repeats. I have carefully watched the flames and notice that after a minute or so, the flame on the burner begins to "lift", then the pilot flame goes out (sometimes just at the thermocouple, sometimes the thermopile, sometimes both). I have a horizontal termination with 20' of horizontal pipe, 5' of vertical pipe, and 3 elbows. This is at the limit for a wall termination, but it is installed per the manufacturers' specs. The dealer is no help and the fireplace is completely finished in an existing house so I don't want to start over. Any ideas? Answer: A flame lifts when it can't get the proper amount of oxygen for combustion. When a pilot flame lifts, it doesn't hit the thermocouple or thermopile quite right and hence less electricity is produced. A reduction in the millivolts causes the main burner and/or the pilot light to go out. Lifting flames makes me want to look at the venting. Oxygen depletion caused by improper venting is the place that I'd start. I'm thinking that there might be some exhaust/intake mixing in the vent pipe. Do you see any sooting? Checking the venting can be quite difficult. I'd also check the air mixer on the main burner tube. Gas and air are mixed right at the place where the gas comes into the firebox. Sometimes the air shutter isn't open enough. 5 ft of vert and 20 ft of horizontal with 3 elbows makes me want to double check the manufacturer's specs. Sometimes every elbow after the 1st counts as 5 ft of horizontal run. I'm not familiar with the fireplace that you have. I'm just trying to make some good guesses. I'm sorry to hear that the dealer is of no help. Isn't something like this covered under warranty?