I have a new Mr. Heater Big Maxx furnace that was cycling the burner on and off. I removed the flame sensor which didn't seem to be dirty but a bit discolored (blue/black) and cleaned it with a pot scrubber. I replaced it and furnace worked great for a day but now it is back to same old thing, gas comes on burns for a few seconds to a minute and kicks back off. Would a new flame sensor help?
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Big Maxx Flame Sensor???
- Thread starter mills00
- Start date
rickairmedic
Well-known member
Mills are you running propane or natural gas . Propane seems to burn dirtier than natural gas but still shouldnt be killing the flame sensor in a day . I would say it sounds more like your unit needs to be adjusted to burn properly. Flame sensors dont generaly go bad . I have been doing HVAC for close to 20 years and have never had to replace a flame sensor.
Rick
Rick
I am running natural gas and the flame seems to be burning clean, it is blue with little to no orange or yellow. When I removed the flame sensor it appeared to be clean other than the discoloration which I would think would be normal, there was a slight grey film that wiped of but other than that clean. I have checked the inlet and outlet pressure as well as the gas valve voltage and all seem to be normal. Is it possible that the flame is not hot enough the end of the sensor seems to be in the middle of the flame. Any and all help is greatly appreciated, I am about out of thing to try.
rickairmedic
Well-known member
Mills one thing does come to mind here doublecheck your polarity on your 120 volt hookup . Make sure its right on newer furnaces with controlboards polarity is quite important.
Rick
Rick
rickairmedic
Well-known member
OK how " new " is new ?
Rick
Rick
rickairmedic
Well-known member
Mills I had a brainfart . Look around the HVAC forum a little I remember a few guys who had a problem with their units and it ended up being the flame rollout switch that was tripping due to an issue with the burners . I would also give tech support a call and see if they can be of any help.
Rick
Rick
The unit is about a month old, I followed your suggestion and tested the limit switches and none of them had been tripped. So I kicked the furnace back on the flame kicked on, the ignitor kicked off - burned for ~10 seconds and flame went out --- same old thing. So I followed your suggestion again and called tech support, they seemed sure that it was the circuit board and are sending me a new one. I appreciate all of your help and will keep you posted after I put the new board in.
rickairmedic
Well-known member
Mills that actualy makes sense seems as I recall reading about alot of bad boards in those units right out of the box. Hopefully thats all it is and you will have heat in a few days.
Rick
Rick