Flame Rectifier Older Pilot Furnace

[Bob G]

Ya'll
  Older furnace with standing pilot. Yesterday I cleaned the flame rectifier it is still in pretty rough condition , pilot lite fine.  Today called back, pilot out again.......
I'm going to take more time with this one tomorrow and actually measure amps and look at flame/rectifier engagement.  While cleaning the rectifier appeared to be far away from flame, maybe only top 1/4" actually getting hit with flames and on angle away from flame instead of leaning towards flame.
Questions;
What's good micro amp reading? 1-4 uamps?
How important is the flame engagement with rod?  should it be almost totally engulfed in flames?
Think I should put in a new one but would like to get readings first.

Thanks guys
Bob

[Hgye]

On a standing pilot, there is no flame rectifier.  It will have a thermocouple.  They don't last forever and you said it looks pretty rough.  It sounds like you need a new one.  They are less than $20.  A working thermocouple measures 15-30 millivolts DC.

[Bob G]

Thanks
I'll put on my thermocouple adapter and measure millivolt consistency with full expectations in putting new one in..

[Bob G]

Was only getting 5-7 mv with pilot on. I took it out and bench tested it comparing to a new one.  Both reacted same with direct heat, no problem getting up to 40mv+ when red hot.  I'm going to put old one back in and adjust bracket position to get more direct flame engagement.
Question - how was the gas valve staying on when thermocouple was only reading 5mv?

Thanks

[Admin]

2 to 5mv can keep the pilot coil open.

Disconnect your pilot tubing and smack the pilot hood with a wrench while you blow through the tube.  That usually cleans out the orifice and gives you a nice strong pilot.  Otherwise look at increasing the pilot pressure to give you a nice flame.  Usually there is an adjustment screw on the gas valve, beside the pilot tube port.