We have a ten year old Rheem Criterion II furnace which willl not light. Can anyone telll me what 5 flashing green lights indicate. Thanks.

Should say on the back of the furnace door, on the control itself, or in your owners manual.

should say on the back of the furnace door, on the control itself, or in your owners manual.

All I can find is "fault" I read on another site that it will flash 5 if the furnace is capable of being "twinned". I don't know what that means.

What runs when you turn the heat on? Does it start to flash as soon as it starts up? Did you turn the power off and back on to reset the board?