Question about Heating & Cooling
The flame sensor is really a flame rectification circuit. Ground to the circuit board is actually conducted through the flame to the flame sensor (ground rod) completing the safety circuit. Sometimes oxidation forms on the surface of the flame sensor inhibiting its ability to conduct the flame but most of the time the problem is on the spade clip that attaches to the circuit board or to the bottom of the sensor itself. A simple removal and scratching/sanding/cleaning of the surfaces of all the ground connections in the sensor circuit usually take care of the issue.
Posted on Nov 23, 2014
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Posted on Jan 02, 2017
Thanks for your question,
The flame sensor eye is located just under the transformer, it is looking straight down the burner assembly to where the burner chamber is at, you will have to remove the entire assembly to get to it, first make sure the power is off, remove the transformer, then remove the entire burner assembly from the furnace cabinet, once removed you can see the flame sensor window, use a clean oil free cloth to clean it, it would probably be a good idea while you have it out to replace the burner nozzle, as over time they will clog, I hope this helps you fix your oil burner, let us know and rate this please, thanks again,
Posted on Jan 27, 2009
The flame rollout sensor is a rather important safety feature that ideally only trips when there's an overtemperture outside of the combustion chamber. I'd encourage you to get a better quality tech in ASAP to check for a cracked heat exchanger, gas overpressure, restricted airflow (changed the filter lately?), maybe a blocked condensate drain if this is a high efficiency furnace. If the sensor was replaced and it's still tripping, you've got a potentially dangerous overheating issue that you don't want to try to bypass.
Posted on Mar 20, 2009
if you have replaced the flame sensor and it will not stay lit, the draft safety switch may be opening. It works on positive and negative pressure created by the inducer fan motor.You may have a restriction in your heat exchanger or if is a high efficiency furnace, it may not have the drain tube installed properly with a trap. The trap works just like the trap under your sink and if water isnt in the trap, the pressures can be effected enough to open the draft switch(some call it an air pressure switch)
Posted on Jan 07, 2010
Good one! Is the flame getting to the flame sensor within the few seconds? Maybe a good cleaning of the burners or flame tray would help. 1.3 ma is enough for the flame rod to tell the board to stay on. Re-do all the ground connections both at the board and furnace cabinet to be safe. Check the polarity of the power going to the furnace. What are the chances the second board is bad?
Posted on Jan 15, 2010
Hi try the pressure switch, clean the flame sensor
Posted on Feb 02, 2010
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