Can't seem to discover why the roll out switch above the top burner trips after about an hour of heater operation. Unitary Products horizontal propane furnace. Filters are clean, vent is clear. Cabinet near burners not excessively warm. The controller blinks 5 times until the switch is reset. Suggestions? Thanks.

The roll out switch could be out of range or defective causing a nuisance trip.

Usually when they trip there is a reason for sure. Get a replacement for that part and make sure it is the EXACT one for that unit. After replacing that part if it continues to have the problem it will be time to call in the on site service person to check for problems with excessive gas pressure or venting. Make usre the unit is moving the correct amount of air in the home. Check the air filter and make sure all vents and return air openings are open.