Heatilator gas fireplace intermittent flame problem

It sounds like the flame sensor may be causing the problem. Near the pilot light there is a metal rod that needs to be clean to sense the flame. One MFG says to clean with "scotchbrite" pads so you don't leave any metal on the sensor and other MFG I believe allow cleaning with fine emery or steel wool.

Easier than that, it is hard to see exactly how it is but I am thinking that there is a metal sparker AND the metal rod (size of pencil lead or toothpick) that is in the pilot light flame. It is the metal rod that needs to be cleaned with scotchbrite or emery paper. No disassembly needed. I made a customer believe in supernatural powers when HHT told me to clean the sensor rod and the similar troubles would go away. That was over a year ago.

can you give us the model of heatilator fireplace this is? That way I am not talking in generalities.

If your pilot looks like this on page 15, it is an IPI (intermittent pilot ignition) and one metal rod is the sparker and the second is the flame sensor. Once the flame is established it quits sparking and if sensor is clean a small current travels through the sensor to the valve and keeps pilot on and also allows burner valve to open. If the sensor is not clean it will not keep the pilot on and the sparker will then try to light again. Eventually it will lock out until it is reset.
My intent was to upload page 15, but I think the whole Bravo fireplace with IPI ignition is here.

It looks like the flame sensor is broke, right? Maybe that is just hard to see. The troubleshooting guide says to insure good connections from the (sensor in the flame) all the way to the control and the manual I looked at yesterday said to clean it with steel wool. It may be the control is bad. If you know the age of the unit, (actually they only need the serial #) it may be a warranty upgrade. Check with nearest dealer. Could call Heatilator customer service.