monitor 422 flashing burner light

[snuff1175]

I recently took apart my heater to replace some bad gaskets, now it starts up and I can see the flame, but after a couple of minutes the flame goes out and the burner status lights are blinking. I think it fails the "flame verification test". I saw a post that mentions using a jumper with a resistor and a diode to troubleshoot the flame detector circuit, but I'm not sure exactly where to jump to and from. Does anyone have any more detailed troubleshooting information that might help? I have looked for days to find a service manual online, but no luck! Any help is greatly appreciated!

[HayZee518]

the flame rod circuit is from the flame rod to machine ground. the test setup goes from the flamerod wire to a good ground on the heater. if the flame goes out again, reverse the test connection. the flamerod should be positioned in the middle between the pot and the burner ring.
the way it operates is there's 120 volts on the flamerod in the absence of a flame. once there is a flame, the air around the flamerod is ionized and conducts, however at this point, the ac changes to dc and is applied to the flame detector circuit on the motherboard.

[hawkins111]

bad flame

Snuff,

Take a look at the posting on 7/29/10 Monitor 422 burner ring. This is what your burner ring looks like as well. I would not bother to mess with the flame sensor until you have looked at the ring and mat. Once you have a serviceable ring and mat you can make a determination about the sensor. The only thing that can go wrong with the sensor is to have a broke wire or carbon on it.

Good luck and keep us posted.

Tom

[snuff1175]

I made the test wire with a diode and a resistor. I let the stove start up and the burner start. Once I saw the flame, I plugged the wire in place of the sensor, and after a couple of minutes the fan turned on and the flame went to high. So I'm assuming I have a bad sensor. I did check the ring and the mat when I had it apart, and they weren't warped. They were in pretty good shape.

[hawkins111]

M422 flashing

Snuf

The flame sensor is doing exactly what is meant to do. Since it does not recognize a flame it shuts the heater off. The flame sensor is just a wire that hangs into the flame and conducts electricity to ground. The only thing that can go wrong with the flame sensor is to have a broken wire or get carbon on it and conduct current to ground or get bent and touch the side.

When you took the heater apart to replace the gaskets and looked down into the burner you would not be able to see the sides of the ring. Your view is blocked by a baffle on top of the ring. You would only be able to see the top of the ring. To do a proper job you need to remove the complete combustion chamber and heat exchanger together from the cabinet. Flip the assembly over and remove the burner from the bottom (4 screws). Now you can see the burner ring. I will guarantee you the ring will look just like the post titled M422 burner ring.

What is needed here is to replace the burner ring and burner mat. Clean all the holes in the burner pot. Replace all gaskets you touch as they are so soft. Use glue on all gaskets and screw heads. You can use either Rutland Cement or the glue from Monitor. The Monitor glue is expensive but it is good stuff. All parts from Monitor will cost about $150 or so. Use the Monitor web site and find a distributor, use their site to find a dealer near you. While you are at it ask the dealer for a manual. They will cost around $30 or so.

Tom