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422 flashing lights after shutdown


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  • 422 flashing lights after shutdown

    Serviced the heater, new burn pot & ring etc and runs fine until temp is reached and shuts down. All lights flash like out of fuel.

    plenty of fuel, swapped main board, air pressure switch and temp wire.

    Any advise is appreciated as I can not find any reference in service manual about this.

    thank you

  • #2
    I will try replacing the carburetor, not sure what else it could be.


    • #3
      Watch the flame when the stove is running. Either the flame is strong and steady when the lights start to flash, or the flame diminishes then the lights come on. Strong flame when lights come on indicates flame sensor issue. Weak or diminished flame is a fuel issue.


      • #4
        If the flame sensor is making contact with flame ring it will cause this. Mine would do this occasionally so I cut the flame sensor off just below the bend and put it back in. It doesn't happen as often now. My flame ring doesn't seem to be warped so I don't know if it and the flame sensor were actually making contact or if carbon was bridging between them causing the problem. Have you checked and cleaned all the filters? The fuel pump also has a screen on the bottom of it. A couple years ago my heater would run constantly on high and not keep the house warm. After checking everything else I could think of I pulled the pump and there was lint on the screen preventing enough fuel from getting to the pot to put out enough heat to keep the house warm. I cleaned it with a paper towel then soaked it in vinegar for a couple hours. The heater has ran fine since.
        Last edited by FordMan59; 02-24-2020, 11:51 AM.


        • #5
          I agree with Fordman on cutting the flame sensor off at the bottom bend. We have done this as a standard procedure for fifteen years now. If you look at a Toyo flame sensor, it does not hang down past the edge of the burner ring. If you do cut it, be sure to cut it right at the bend. The screws that hold the flame sensor bracket should be tightened the same, as not to force the rod in or out.


          • #6
            I replaced the carburetor and the fire valve and my issue went away.

            the 422 was fully serviced, new burn pots/ring. Fan bearings, combustion was oiled and replaced the o-ring along with cleaning the carburetor and filter and needle valve.

            the heater ran perfect until it went through shutdown, and turned off - that’s when all light would flash like out of fuel.


            • #7
              How high above the set temp does the stove run before it shuts down? Also, does the flame cut out completely very shortly after the Status Lights go out?


              • #8
                Msearcher, Did you get your M422 going again?


                • #9
                  Yes, replaced the carburetor


                  • #10
                    re: question about yellow flames in the area of my flame sensor rod, related to above discussion.

                    Originally posted by hawkins111 View Post
                    I agree with Fordman on cutting the flame sensor off at the bottom bend. We have done this as a standard procedure for fifteen years now. If you look at a Toyo flame sensor, it does not hang down past the edge of the burner ring. If you do cut it, be sure to cut it right at the bend. The screws that hold the flame sensor bracket should be tightened the same, as not to force the rod in or out.
                    Tom Hawkins or FordMan, hi. My Monitor 422 is working fine, and had a refurbish with new pot and ring in October 2017 with new parts, gaskets, etc. I'm in Mount Shasta, CA, and winters are really mild here, so the 422 is very low usage. It is probably around 20 years old, but low 'mileage'. ;-)

                    But I do see some unusual "yellow flame" activity through the window, and it seems to be coming from the area of the flame sensor rod, near as I can tell from the window. I've uploaded a short video at this link, you can see it with link below. As you can see, the overall flame quality is great, as is the flame ring. Just the yellow near the sensor.


                    Do you think this is caused by the lower bend in the flame sensor rod, and that I should cut it off as you mention in the above quote? Could any damage result from leaving it like this? The higher amounts of yellow from this area only show up when the heater is running at medium or high, not on low.

                    Regards, William Croft, Mount Shasta, CA
                    Last edited by wjcroft; 11-18-2020, 07:20 PM. Reason: bad video link


                    • #11
                      I doubt the flame rod has anything to do with the yellow flame. The reason I cut the flame rod shorter was to help prevent it from shorting out on the flame ring so easily. I couldn't get your file to open so I didn't get to see the flame, but unless there's a lot of yellow and pretty well constant I wouldn't worry about it. Have you checked that the gasket around the flame rod is good and that it's not getting air there that it shouldn't be getting? I bought a 422 for my son several years ago. It came out of CA and looked and run like new even though it was probably between 15-20 years old at the time. Hawkins can probably help you determine the problem better than I can since he used run a heater business.
                      Last edited by FordMan59; 11-17-2020, 09:50 PM.


                      • #12
                        FordMan, hey thanks for the comment. The gasket for the flame rod sensor was new in October 2017 when I did the refurb. Screws are tight.

                        That's odd about the video link. [Just replaced with a Youtube link below]


                        Regards, William
                        Last edited by wjcroft; 11-18-2020, 07:19 PM. Reason: bad video link


                        • #13
                          I still can't get the video to load this morning but, as long as there's not much yellow in the flame and the sight glass isn't sooting up I think you'll be fine. My 422 has been in service almost 23 years and has only had one flame ring and two burn mat replacements in that time. I few years ago when I replaced the burn mat I took the flame ring that I'd installed in 2012 to a welding shop and had them weld all around the circumference of the dome to hopefully prevent it from coming apart or warping as easily. If I ever have to take it apart for anything else I'll check to see how it's holding up. If the weld is breaking I'll have it re-welded. Those flame rings are getting so expensive we need to do whatever we can to make them last longer. I occasionally get a yellow flash but, it doesn't last but a second and usually when I get that flash is when the heater changes operation speeds. I wonder if the burn mat is lifting if that would cause a yellow flame or not.


                          • #14
                            You can not see the condition of the flame ring on a 422 through the window. The viewing hole is too small. A leaping yellow flame is a sign of a bad burner ring or burner mat. I have only tried twice to weld the burner ring, with no luck either time. The metal gets so corroded by the heat cool cycle it gets brittle and hard to weld. When you do open it up take Fordmans advise and cut the last bit off the flame sensor. This gets the rod up out of the space between the ring and burner pot. It should end right above the edge of the ring. At some point in the near future the stove will start cutting out due to either soot or contact of the flame sensor. At that point you will have to open the stove one way or the other. Mount Shasta is a cool spot. I've been through there many times.


                            • #15
                              Tom and FordMan, sorry for my issues with the Google Drive link, Drive was not cooperating. I just re-loaded the video using a Youtube upload. Here is that link below, just click and it should play. What is shown is the 422 running on I recall '3/4' on the Burner Status LEDs. This yellow area of the ring only seems to show up the higher burner output ranges (1/2, 3/4, and high). On lowest, where the 422 is at much of the time, there is no yellow visible. On the video I tried to show that the flame quality in the rest of the ring (95%) is fine, good blue tiny flames, and ring is red from the heat. Only in this small portion of the ring near the flame sensor is the flame acting up. I don't see evidence of soot yet.


                              Tom, if you view this, does it look more like a mat issue or ring issue? All components were OEM brand shiny new when I did the refurb in October 2017: pot (with pre installed mat), ring, gaskets, etc. Looking more closely today, when the flame was on low, it does seem like there is a bit of distortion or non smoothness in the red glow of the ring, at the location where the yellow appears when running on high.

                              As I mentioned Mount Shasta winters are very mild, most of the time only near or above freezing. Only a small number of days in the 20's. So I would have expected all the new components from 2017 would last more years than this. A couple things to note: I have been shutting it off over night (just heating my bedroom with an electric radiator). So when turned on in the morning, it does run on high for some time; getting the temp up from around 60F to 70F. Perhaps these periods of 'high' times have stressed the ring.... If I left it running on say 65F overnight, that would probably be less time in high, when I go to 70F. And less thermal shock.

                              (I guess you've ruled out the flame sensor rod position as having anything to do with this yellow. But let me know if this video changes your opinion.)

                              One other item that I remembered: my outside 275 gallon split tank (I only use half), had water condensation issues when I got here in 2017. Since then I've been adding a small amount of K-100 to the kerosene, to mop up / absorb any water that might get into the tank. As far as I assume (and read reviews), the K-100 is a formula that can absorb water, but does not change the fuel characteristics. But let me know if you've heard any bad things about it. Don't see how this could damage the ring.


                              Regards, William Croft, Mount Shasta
                              Last edited by wjcroft; 11-19-2020, 03:24 AM.