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flame has difficulty staying lit (Munchkin)

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Yes, the PVC slopes towards the boiler. I'll fix it over the summer and see if that helps. Thanks!

Comments

  • John Ketterman
    John Ketterman Member Posts: 187
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    Watched a Munchkin while it is starting up, and it got me worried. It never succeeds the first time.

    The spark lights the gas just fine, and then it stays lit for a little while. (Flame sensor failure would turn the gas off sharply and immediately, so that's not the problem here.) After some seconds the flame goes very low. I believe Munchkins are programmed to try the lowest modulation first and then slowly go up if needed. Anyway, as soon as it goes to low fire it has difficulty staying lit: there's a pop-pop noise (like when you try to blow out a gas stove flame) and the flame goes out.

    Usually it stays lit by the third try, but it seems to me it's only a matter of time until it fails three times and I get an F09 lockout.

    All suggestions appreciated.
  • clammy
    clammy Member Posts: 3,111
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    munchkin

    Is this a newer or exiting installation ,check all grounding termanals,also check incoming gas pressure besides cleaning the flame sensor was this unit adjusted with a combustion anlyser?Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • bobbyg_2
    bobbyg_2 Member Posts: 139
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    I've seen this happen once. The exhaust vent line wasn't sloped properly and it held water. (I wasn't the installer :-)

    It did exactly as you described. I would first check the exhaust vent piping for any obstructions, etc.

    It seemed to work fine at a higher rpm fan speed. But at lower fan rpm speeds it would flutter and pop. Try that.
  • John Ketterman_2
    John Ketterman_2 Member Posts: 12
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    Existing installation, gas pressure OK, no combustion analyzer used to my knowledge. I'm the owner, not the installer.
  • Pinball
    Pinball Member Posts: 249
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    Read the manual! the vent is supposed to slope to the boiler.
    1/4" per foot. also you CANNOT set these boilers up without a combustion analyzer. If the installer did'nt do it, either get them back ,or get someone who has one and knows how to use it, to adjust this unit.
    Check the condensate line for proper pitch as well(away from boiler) and if it is an older model, make sure the little vent hole is NOT blocked.

    Al (Pinball)
  • Chris_82
    Chris_82 Member Posts: 321
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    Good luck john,...

    Munchkins always worry me,...esp. watch out if your next to one. I.e., always watch the sky for falling houses,...Check everything including the intake fan, they haven't yet soved this problem, of course as your going to find out there are going to be lots and lots of suggestions as exactly "fix" your equipment, that should tell you something!
  • GW
    GW Member Posts: 4,693
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    uhh

    was that called for? I have never heard of a Munchkin falling from the sky; has anyone else?

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
  • Paul Rohrs_7
    Paul Rohrs_7 Member Posts: 173
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    Sky is falling?


    I had a glitch with a modcon (not Munchkin) a week ago and it had been installed correctly, set up with a combustion analyzer, blah blah blah. Following commom sense and the trouble-shooting guide didn't help, but it was still correctable, and eventually was corrected. Was it frustrating? you bet. Did I learn something I hadn't known before? you bet!


    Regards,

    PR
  • clammy
    clammy Member Posts: 3,111
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    flame sensor

    John you can go through the menu on the control and see what the resistence of the flame sensor is in the instruction i believe it should be like 3.5 to 4.0 but check the manual for the exact specs ,also check the grounding wires your best bet is to locate a pro and have them do a combustion test and go over the boiler there's a few smaller promblems that will give you the promblem ,blocked condensate drain ect good luck andpeace clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
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    > John you can go through the menu on the control

    > and see what the resistence of the flame sensor

    > is in the instruction i believe it should be like

    > 3.5 to 4.0 but check the manual for the exact

    > specs ,also check the grounding wires your best

    > bet is to locate a pro and have them do a

    > combustion test and go over the boiler there's a

    > few smaller promblems that will give you the

    > promblem ,blocked condensate drain ect good luck

    > andpeace clammy



  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
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    To expand on this line of thought...

    Depress the S4 button for 3 seconds. You should get a D1 alternating to a value. Press the S4 button 6 more times to get up to D7. The value that is displayed is the flame rectification signal. The unit should turn on and light at about 2.5. It should never fall below 1.9-2.0 as the unit ramps down to lowfire as it works it's way up to 4.0-4.1.

    If the unit is older than a year, it's time to have your contractor return and do a maintenance on the boiler. A 'dirty' flame rod could be the cause of your problem.

    Good luck.
  • John Ketterman_2
    John Ketterman_2 Member Posts: 12
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    As I mentioned in the original message, it is not the flame sensor. I have that problem before; if the flame sensor doesn't detect a flame, the flame goes out sharply within a couple of seconds after being lit. It never has a chance to ramp down. It does not last this long, nor does the flame flutter. Anyway, I did check the sensor current, as you suggested, and it is behaving correctly. But the flame still goes out after a while.
  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
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    Was there any fluctuation in numbers?

    What were the flame current numbers? The reason I ask is that an F09 fault code is the boiler not sensing any flame.

    What you are describing would actually be an F10 lockout. An F10 fault is the boiler lighting, seeing a flame and then dropping out 4 times during 1 call for heat. Generally those kinds of failures are related to condensate management. Either condensate pooling in the exhaust pipe as described in one of the messages above or that condensate is backing up inside the boiler. Possibly due to a plugged trap.

    F09's are that the boiler didn't light at all or the boiler lit but didn't sence the flame.

    What model unit are you working with? Do you ever get more than 3 tries before the lockout occours? Is the little green light illuminating on the display pad? The light under "flame on"?
  • Bill de Jong
    Bill de Jong Member Posts: 15
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    Our experience in the Wild, Wild West of Canada is that you MUST properly the unit's gas valve with an analyzer. The symptoms you are describing are similar to installations we have been involved in. Good Luck!
  • Greg_40
    Greg_40 Member Posts: 43
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    Falling houses are bummers on wicked witches, I don't recall any Munchkins being injured during filming the Wiz. of Oz. They'd have to put in a disclaimer if filming it today!

    Partial intake air blockage by water, debris, shrubbery, etc. would be my first notion to look at. I've seen draft induced 80% furnaces huff & puff when firing up. Bird nests were the cuplrit in those cases.
  • John Ketterman
    John Ketterman Member Posts: 187
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    Sorry I said anything about F09, my mistake. You will see from the first post that actually I never had any error code. I only saw the problem because I was watching through the window. It always lights the second or third time--so far.

    The sensor current behaves the way it should, no fluctuations, until the flame starts to flutter and go out, and then of course the sensor reading fluctuates and finally shows no flame. So there is never a situation where the sensor reading is out of range and then the flame goes out. The flame goes out even though the sensor is reading OK.

    The model is a T80M and yes the little green light comes on.
  • John Ketterman
    John Ketterman Member Posts: 187
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    Thanks, I'll check the air intake when i get home.
  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
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    Ok still a tad confused.

    Previously you said the flame does not flutter... but in this reply you say it does. Perhaps it flutters some of the time?

    Does the overall glow of the combustion chamber on low fire get very dark? Like a dark blue? If so it sounds as though you are in need of some more gas on the low end to help stabilize the flame.

    Since a combustion analysis has not been done I think you'll find that it will correct the problem. If the age of your boiler is >1 year and this problem has recently developed, it sounds like you may need to have the boiler maintained too.

    Good luck to you.
  • Al Corelli
    Al Corelli Member Posts: 454
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    Blocked intake?

    A Shrubbery?!

    (Old Monty Python quote)
This discussion has been closed.