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Thread: MPI Monitor 422 Status Light Question

  1. #1
    jdh
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    MPI Monitor 422 Status Light Question

    My 422 has been running just fine, but recently I've noticed a strange behavior with the status bar light on the top panel. while running along just fine, once in a while the status light/bar will blink off for a second or two then come back on. During that time the flame becomes thready. When the bar comes back on the flame becomes healthy, again. I'm hearing no "ticking" sound from the fuel pump, so I assume that the bowl is getting enough input fuel flow. No faulting or error codes have ever displayed on this unit. I had another that would fault out because of a dirty flame sensor rod. This unit has never done that.
    Any Ideals? Winter is coming, here in Alaska, and that glitch makes me nervous.

  2. #2
    hawkins111 is offline Journeyman
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    M422 trouble

    JD,

    This is the first sign of the need for a combustion chamber overhaul. The flame is wavering around and coming off the flame sensor. More than likely you will need a mat and new burner ring. Iím in Bethel, where are you?

    Tom

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    jdh
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    Sounds logical

    Near Biglake, now. Used to live up along the Kashwitna.

    I was afraid of that.... Have noticed a flickering tongue of flame, during warmup, in the area of the flame sensor rod. My concern was that: if the interval of time that the status light is off increases, would the mat/chamber cool enough to prevent re-ignition and lead to flooding or overflow of fuel. Right now, the flame only gets a bit weaker (thready) before the light comes back on... then the flame gets nice and strong... until it happens again. This seems to happen when it is running in the normal mid-range (half the status bar lit). Only have had the unit hit the full-bore cycle (all bars lit) a few times... and I didn't notice it happening, then.

    Yes, I can follow your logic, now. Would explain what is happening.

    Am I right in assuming that if the interval gets longer, it would go into shutdown from lack of flame detection... rather than flood the chamber?
    My old one, that I mentioned, would run on low flame cycle okay, until it would kick to high range. Then it would shut down after a few minutes, from lack of flame detection, with the flashing display, until I would do a reset. Periodic cleaning of the sensor rod and tweaking the position kept it going, last winter. Got tired of it and am going to use that older one for spare parts.

  4. #4
    hawkins111 is offline Journeyman
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    combustion chamber OVH

    The combustion chamber needs to be overhauled. The ring had warped to a point the flame is not getting on the sensor correctly. As long as the igniter works the stove will not flood. If you do not see a flame in the pot, stop trying to start the stove. Each time you try fuel is sent to the burner pot. If it does not light it builds up to a point that floods the burner and then you really have a mess. Get both stove to a service guy for a through service.

    Tom

  5. #5
    jdh
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    I'm greatful for the input

    Yeah, the older Monitor is history. I gutted it a month ago and saved all the parts. The board, pump, bellows, fan, etc where all in good shape. Figured to save the parts for this newer one, as there is nobody near me that works on them. Besides the prices on these parts have gotten crazy. With limited means and me getting older, it seemed like the smart thing to do.
    You addressed my concern on the flooding. Don't need a mess at this point.
    I figured this newer one was developing some issues when I noticed the burner status behavior. Burner ring warping and flame detection would explain the problem. Up until this time it has been running just fine. Had the front off the chamber, early this summer and sucked out the tiny bit of soot inside. Everything looked good then.
    So, if this Monitor follows the same path as the old one (the old ones burner ring was wreck... edges erroded and tack weld problems) it will get worse, I know. For now, the flame gets weak, during that status bar blink, but doesn't die out and comes back strong when it detects the flame, again.
    Will try to locate a replacement burner ring.
    I know that it isn't the best way to do it, but to keep it going for a short while longer... is it feasible to just pull the top, heat shields and cap and replace the burner ring, that way?

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    hawkins111 is offline Journeyman
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    complete job

    There is no way to get to the bottom of a M422 from the top. There is a baffle over the burner ring that keeps you from getting to the bottom. There is no short cut to a new mat and ring. You have to remove the whole burner and heat exchanger together. Flip it over and go through the bottom. You will tear up, the chamber gasket, igniter and cover gasket, flame sensor gasket and the gasket on top of the burner. Since you will need to clean the window you will mess up the window frame gasket. Along with a new burner mat you will need a new burner ring also. You will also need some glue for the mat. Monitor glues all screw heads as well as gaskets on the fire side of the chamber. Just buck up and do a complete job. The first time will take a couple of hours. Let the glue dry for another couple of hours, then fire the unit. While waiting you can change the filter on the tank.

    Stay warm,

    Tom

  7. #7
    jdh
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    Mental Hiccup

    **(head-slap**
    Should have known better than to ask it... forgot all about that baffle. Noted it when I scrapped the old one...
    Will locate a burner ring and mat. Then will see what can be done. As to removing the front cover and checking out the position of the sensor, will still do to clean it, ... and out of curiosity. Had to do it a number of times on the old one. I dearly love the bulk gasket mat stuff I picked up in Anchorage, a couple of years ago. Sold by the foot. Been cutting out those gaskets since (got both thicknesses). Even bothered to make up some rigid templets.
    Again, thanks folks for the input and encouragement.
    A great forum, you have, here.

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