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Munchkin no flame once/day every day

J. Cricket
J. Cricket Member Posts: 36
Our Munchkin is failing with an F10 (multiple failed attempts to light). I have cleaned the flame rod, which was clean to begin with; the current when running is 2.5 to 3 microamps. Boiler was cleaned in the fall.

The strange thing is that it is always fine when we go to sleep, and it ia always F10 in the morning. I reset it and it lights up first try every time. Then it runs fine all day. Next morning, F10. This has been happening for the last 7 or 8 days.

It is not so warm here that the boiler only runs at night. It runs day and might, although of course the water temperature is low.

All suggestions gratefully received.


  • tim smith
    tim smith Member Posts: 2,738
    F 10 error. Microamp reading is suppose to be a min of 4, it

    is too low on your boiler. could be combustion setting or could be the ground path for flame rod from burner head to outside mounting plate. My .02 worth for now. Tim
  • J. Cricket
    J. Cricket Member Posts: 36

    OK, I'll check the connections, but my manual said if the current is less than 1 μA, there's a problem there..
  • Steve M_2
    Steve M_2 Member Posts: 121
    Munchie problen

    Did the company that did the cleaning, really do a heat exchanger cleaning? They need to remove the burner to access the exchanger to clean. Also the older Munchies you need to check the screws that secure the burner to make sure they're not loose. If they are loose, that means the ground path is interrupted and if affects the flame retification signal. You need to remove burner, replace the gasket and clean the screw threads and contact points, I use a scotchbrite pad.

    You really need to get an experienced Munchkin person for your annual cleaning and service. Lets us know how it goes.
  • clammy
    clammy Member Posts: 3,092
    flame rod

    since you already know how to go through the menu ,run the boiler to hi fire and check the probe reading if it is not reading at least 4.0 then replace the probe ,when your unit was last serviced did they run a combustion anly on it if not find a company that has a digital comb anly ,the probe an give lower readings if the combustion settings are not corret ,peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • J. Cricket
    J. Cricket Member Posts: 36

    On high fire it does read 4 μA.

    What happens during a normal start upon call for heat is that the current goes to 4, then the flame is cut back and the current drops briefly to about 2.5, then it stabilizes at 4 again.

    What happens when there is a problem is that the current is about 2.5 to 3 when it lights, and then when the Munchkin throttles back, the current drops below 1 and at that point shuts off.

    I would call a professional except that when you have an intermittent problem like that, it's not going to happen when he's there. Why would a flame rod or ground connection be good most of the time and bad some of the time?
  • Steve M_2
    Steve M_2 Member Posts: 121

    "Why would a flame rod or ground connection be good most of the time and bad some of the time?"

    I guess you didn't read my post.
  • J. Cricket
    J. Cricket Member Posts: 36

    You said the ground path could be interrupted, you didn't say it would be intermittent.

    I'll look into screw cleaning.
  • Darrell_4
    Darrell_4 Member Posts: 79

    The ground path can be intermittent because the various metals involved are highly reactive to heat, or the lack of it, which can cause tight connections, or pathways, at one time and not another, depending on the state of the various components. A period of setback at night might be allowing the various components to cool to a point where good contact is broken. When you hit the reset it goes to high fire and the problem is solved...temporarily. A good service tech will check all of these things as well as clean the heat exchanger at the same time. A though cleaning and check will often eliminate nuisance lockouts by virtue of loosening, cleaning, and tightening the connections.
  • J. Cricket
    J. Cricket Member Posts: 36

    I took it out and cleaned the contact area. Steve M said I should clean the screw threads, but actually the electrical contact is over the entire ring-shaped area between the burner 'lip' and the boiler lid. There was some strange white stuff caked on the lip; don't know what it is and it needed quite a bit of scrubbing to get it off.

    Anyway, I did that last night, and this morning was the first morning I didn't get an F10, but we'll have to see.

    I wish I'd known when I got this boiler how many different problems it can have. I've never had a catastrophic failure, but a series of little things (flame sensor needs frequent cleaning; the insulation rings/disks on the lid and on the back wall both disintegrated; drain clogged up; lots of coffee grounds to be removed each cleaning; electrical connections flaky...). And as noted in previous posts, many service people don't know this boiler.

    My thanks to everyone for their help!
  • J.C.A._3
    J.C.A._3 Member Posts: 2,981
    Do you.....

    Have a combustion analyzer ?

    Every problem you describe and symptom you speak of REEKS of "improper burner set-up".

    Get someone with the proper tools and training in there...and be done with it.
    Nuisance lockouts are more times than not, directly related to proper burner settings....and if you ain't testing...your guessing!

    Do you truly believe that your circumstances and setting is EXACTLY like the ones that are tested at the factory?
    This is the only way I can think to describe the "PROBLEM?"

    Every situation is different...and has to be accounted for. Blaming the equipment is a bogus excuse. Blaming the installer for not checking the variables is more likely than not, the culprit.

    Get someone who knows how and why they are reading an analyzer in there.When you've found the one that does...keep him coming back annually and your problems are solved. JCA
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    I've been upgrading all

    the Munchkins I installed and some for customers who have found me. I upgrade both target and burner door refractories to the new ones. They are now made of a better, tougher material. I take off the burner and clean it out, replace the burner gasket, and WIRE BRUSH the burner screws before re-installing the burner. That is the pathway for the rectification. Make it easy for the electrons, and they will treat you nicer. :) I then upgrade the control to the new 926 control with longer post purge cycle and higher rectification voltage that goes to the flame sensing rod AND now uses the spark ignitor as a flame sensing device too. That's right. You get 2 flame sensing devices instead of one. Not a cheap upgrade but everyone I've done has made the boiler works wonderfully. You will love your Munchkin again. It just needs a little love and understanding. WW

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • J. Cricket
    J. Cricket Member Posts: 36

    >Every problem you describe and symptom you
    >speak of REEKS of "improper burner set-up".

    Ok. I'll look into that.
  • J. Cricket
    J. Cricket Member Posts: 36

    I hadn't heard there was a new controller. I assume it has all the same connectors, so it is an easy replacement, no major modifications?
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Yes the new controller

    926 has a longer 90 second post purge. I was told it was most beneficial to the model 140M and 199M because the old controller turned off the fan with a lot of heat still in the Heat Exchanger. This heat would migrate up and cook the inducer blower and motor causing premature failure. D'oh! Tuning up with a combustion analyzer is a no brainer. It's gots to be dun for trouble free operation. WW

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  • Steve M_2
    Steve M_2 Member Posts: 121
    Look for....

    You can tell if an combustion test has been done if you see a hole drilled into the PVC on the exhaust side, usually red siliconed or aluminum taped over. Never the less, you should have it done again if its been a couple years, things change.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669

    How is the boiler vented? It sounds to me like you have an exhaust gas reversion problem.
    The boiler can not be vented with a concentric vent termination.
    The exhaust must be above the exhaust by at least 2 foot.
    I put a 45* aimed up with a SS screen in it.
    The other option is to seperate the intake 6 foot up wind.
  • J. Cricket
    J. Cricket Member Posts: 36

    Boiler has concentric vent. The manual clearly shows a sidewall venting diagram with concentric vent, so why can't a concentric vent be used?

    PS After cleaning the contact area between the burner and the body, the boiler seems to be running fine so far although it's only been 24 hours [update: 36 hours]. Comb analysis yet to come.
  • J. Cricket
    J. Cricket Member Posts: 36

    Mine is a T80M, no indirect. Would the 926 upgrade ($350 for parts, plus labor) have any advantage for me? You said I would love my Munchkin again. What change (other than the post-purge) will I see? Nonlinear reset curve? More intelligent modulation? Better diagnostics? Is there a web site listing the changes?

    Many thanks for your help!
  • R. Kalia

    I wish you the best of luck in an obviously "nagging problem" that would try anyones patience.
    You have received (by the powers of deduction), absolutely impeccable advice from the best pros to diagnose your query.
    Good Luck, and I wish you well!

  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479

    control will give you better rectification current. It uses a higher voltage. The control also doubles it's sensing area by using the flame rod AND the spark ignitor to sense the flame. Better than doublemint gum. WW

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • J. Cricket
    J. Cricket Member Posts: 36

    I am aware of that and I am very grateful to everyone. I know there must be the urge to say "Just go hire a professional" to every homeowner.
  • J. Cricket
    J. Cricket Member Posts: 36

    > Do you have a combustion analyzer ?


    > Every problem you

    > describe and symptom you speak of REEKS of

    > "improper burner set-up".

    It was perfectly tuned (CO 15ppm low fire, 100ppm high fire).
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669

    I know the instruction shows that you can use a concentric vent but BELIEVE me using one or not having the two pipes seperated will cause LOTS of problems.
    Look at your blower and gas valve assembly - are they nice and shiney or are they dull.
    I am betting they are dull.
    If they are dull then you have reversion.
    Is the boiler anywhere near the laundry room.
    If it is then I suggest sealing the door to the cabinet so that NO house air can get into the boiler.
    I service LOTS of Munchkins and pick up new customers every year from other companies that don't know how to properly service a high eff. boiler.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669

    I install the intake with at least 12 inches of clearence from the ground or usuall snow level. I use a down turned 90* without a screen, The 90* is installed tight to the house. Then I put an upturned 90* on the exhaust and go up at least 2 feet and then put an upturned 45* on top of the 2 foot pipe. If it is a short run I will put a reducer in the 45* to help direct the gasses up and away. With 3 inch I use a 3 to 2 reducer, With 2 inch I use a 2 to 1 1/2 reducer. I then put a screen in the reducer. I have 4 year old Munchkins with shiney gas valves. ( started being anal on the venting 4 years ago )
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    I agree

    I make sure there is good separation. I went back on early jobs and contrived an extension on the out pipe of the concentrics. Looks a little funny but whent eh boiler is on low fire the flu gases come out kind of lazy and can easily turn around and come back in the combustion air inlet. Good advice all.

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  • D107
    D107 Member Posts: 1,849
    wayne & steve--can you post photos of your venting

    devices, might be a way to solve alot of problems. maybe the manufacturers will follow your lead.


  • JoeM
    JoeM Member Posts: 2
    Munchkin Burner cleaning

    I am battling with a Munchkin M80R I have the inevitable F09 , 5 years old never been cleaned or maintained. I have replaced the blower motor already and prior to that is when the F09 started . I replaced the igniter and the sensor . I had an issue when it would not restart I took the sensor out and blew in compressed air into the chamber and it restarted. I figured it was time to clean it out. I read the book and figured since I already had a working knowledge of the furnace I would clean it myself.  I took it apart and opened it up and found some crud inside and sprayed and cleaned it down and vacuumed it out.  I found that the burner was a little loose and I could move it back and forth. I didn't think much of it until the F09 kept occurring. I read one of the posts and low and behold it was a point of contention that this could be the source of my F09 . I ordered the gasket and plan to replace it .

           Finally here is my question. . can I soak the burner in CLR I blew it out with compressed air and used the shop vac on it and could feel suction when I was vacuuming the cylinder and thought perhaps this was clean enough. The flame through the window is yellow/blue  and it used to be blue. can I soak it or should I just replace it.
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