Question: We have an Arrow DVi40 direct vent nat. gas insert, manufactured by Heatilator. It stays on for a few minutes with the main burner going, but usually shuts down within 5 or 10 minutes. I say usually because it has stayed on for a day once, and occasionally stays on long enough for the fan to come on (about 10 to 15 minutes.) When it does shut off, I think it is the main gas safety shutoff which shuts. We need to restart the pilot to get the main gas going again. Because the problem isn't 100% repeatable, I think it may be a grounded wire. As far as we know it was store showroom model. The store seems to wipe their hands clean of any problems because I installed it myself. I am positive it is installed per instruction manual, although the shutdown is similar to an exhaust leak back into the intake. Answer: First of all, the store should not wipe their hands clean. Either the store or Heatilator direct should at least help with troubleshooting over the phone.<p> Let's talk about two potential problems. 1. The pilot flame is not turned high enough to generate sufficient millivolts. It works fine while on pilot, but once the main burner turns on the output to the pilot is reduced. There is usually a pilot adjustment screw. You can also use a multimeter to check the millivolts (with burner on and off) against spec told to you by the manufacturer. It also could be a bad thermocouple/pile but there is more chance of a low flame. 2. Bad overheat sensor. Usually located above in in the top of firebox. Shuts valve down in case of excessive temperature...If sensor was bad, or if unit installed incorrectly (not enough pipe rise, etc.) this could trip I agree that the store and/or company should help with troubleshooting.