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Munchkin T80 problem

Sirlimey
Sirlimey Member Posts: 13
I have a wall mounted Munchkin T80 that is 3 years old. I have never had a problem and has worked great. Recently I have noticed it makes a noise out of the blower when it reaches temp and shuts off. The only way I can describe the noise is like a very deep deep voiced whoope cushion noise for about 2 to 4 seconds. It is very load and I can hear it upstairs even though it is located in the basement. Any ideas to what this could be.

Comments

  • icesailor
    icesailor Member Posts: 7,265
    Munchkin T80

    Take the cover off and look carefully in to the blower assembly. The air and gas come in from the left. The gas mixture goes out from the right. Between the fan and the mixing chamber, notice a white plastic spacer plate. Look very carefully at the plate and notice that it has curling vanes. See of they are deteriorated. This is the "Swirl Plate". It may need to be replaced. You can take the cover off and try to see what is happening when it makes the noise but experience seems to show that it doesn't happen as often when the cover is off. If it will do it for you, look carefully at the plate. Get a narrow flame mirror and look all around it. If you see a place on the outside of the swirl plate that is a different color from the rest, it may be "backfiring". The flame is being pushed back through the burner cone and igniting in the mixing chamber. Where the fan mixes the air and gas. Then being recirculated as a flame. You may be able to see it with a flame mirror.

    HTP has replacement plates that have a higher heat resistance to improve this problem. It is not "Backfiring"though. It is recycling exhaust gas through the intake. Even when the cover is off and it is getting its combustion air from inside.

    The other thing is be sure that there is no obstruction in front of the exhaust. I've seen bushes planted in front of the concentric exhaust or once, a big cast iron decorative plate to hide the termination.

    The moaning noise when running is the symptom. The swirl plate is the solution. Are you using LP? LP seems to do it worse that Nat. Gas. 
  • Sirlimey
    Sirlimey Member Posts: 13
    Perfect diagnosis.

    Thank you perfect diagnosis. As soon as I took the cover off I could see the swirl plate was a patchy off white color and had clear cracks all around it. If you have time and link a new durable one I could by I would appreciate it. I do have an LP T80. Thank you again
  • Sirlimey
    Sirlimey Member Posts: 13
    Perfect diagnosis.

    Thank you perfect diagnosis. As soon as I took the cover off I could see the swirl plate was a patchy off white color and had clear cracks all around it. If you have time and link a new durable one I could by I would appreciate it. I do have an LP T80. Thank you again
  • icesailor
    icesailor Member Posts: 7,265
    Munchkins:

    Contact Heat Transfer Products:

    http://www.htproducts.com/

    It's not that difficult to change. If you are in New England, F.W. Webb may have them in stock or get it for you.

    While at it, the combustion area should be cleaned and inspected. Then, you need to combustion test it and set it up properly. All these Mod/Con boilers need to be combustion tested and cleaned. Get the gaskets you need to do the job while there.



    Good Luck. Great boilers.  
  • icesailor
    icesailor Member Posts: 7,265
    LP Munchkins:

    The LP Munchkins seem to be more susceptible to this. You need to get the gas valve pressure just right. A friend that does a lot of Munchkins asked me what I thought about LP gas being variable. Gas pressure from the regulator in and gas pressure from the valve to the burner could be variable and contribute. Even composition. They had that problem with LP being delivered with no odorant in it. Maybe Tim McElwaine will see this and comment. I know that my friend messes with the gas valve pressure somehow (I think) and seems to have good results.

    Like oil burners, these all need TLC and adjustments.
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    T80

    What year is your boiler - it says the date of manufacture on the rating plate.

    If it was built in 2004 then you need to check for carbon monoxide  ( flue gas ) leakage at the back of the cabinet  down behind the heat exchanger. The 04's had a bad exhaust connection. If the swirl plate is going bad along with the blowers and controlers it is a sign of reversion. How is your boiler vented? The exhaust pipe must be at least 18 inches above the intake. If you have a concentric vent you need to change it or modify it to raise the exhaust pipe. Exhaust gas reversion will distroy your boiler.
  • Sirlimey
    Sirlimey Member Posts: 13
    Swirl plate.

    I am out on Nantucket and deal with Webbs so I will give them a ring. I was talking to a guy last week who works on Munchkins and asked if they ever to need be maintained to which he said yes. So think I will be calling him over to do a tune up sooner than I thought. Thanks again.
  • Sirlimey
    Sirlimey Member Posts: 13
    New regulator

    My house is only three years old so do you and so is the regulator do you think it is worth looking into a better quality regulator and if so do you know of one. Or is this just a perk of having LP
  • Sirlimey
    Sirlimey Member Posts: 13
    New regulator

    My house is only three years old so do you and so is the regulator do you think it is worth looking into a better quality regulator and if so do you know of one. Or is this just a perk of having LP
  • Sirlimey
    Sirlimey Member Posts: 13
    New regulator

    My house is only three years old so do you and so is the regulator do you think it is worth looking into a better quality regulator and if so do you know of one. Or is this just a perk of having LP
  • Sirlimey
    Sirlimey Member Posts: 13
    Date

    The tag says 2007 and it is conncentrictly vented. Do you really think I need to change venting.
  • Slimpickins
    Slimpickins Member Posts: 323
    maybe

    With concentric vents,  it will pull in exhaust gases on low fire. If you can insert a extension of 12" on the outlet of the concentric, do it till you can revent it. Depends on what kind it is, you can't do it with the flush termination concentric. 
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669
    edited February 2011
    venting

    You need to raise the exhaust pipe. What I do is cut off the end of the funnel and put it back onto the pipe then install an elboe straight up with a piece of pipe 18 inches long. Then I put a 45* elboe on top to direct the gasses up and away. Put a 1/2 mesh stainless steel screen in the 45*.

    I am not worried about rain getting into the intake.

    You need to have your boiler serviced by someone that the local distributor for Munchkin recomends.

    Check for a bad burner gasket and bad gaskets between the blower and the burner.

    The opaque rubber gasket can get blown out.
  • icesailor
    icesailor Member Posts: 7,265
    Munchkin Regulators:

    There's nothing wrong with the regulator, it's the adjustment. You need to know what you are doing when adjusting it. Like a digital manometer and combustion testing.
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,472
    Allow me to add

    an unpgrade that can help prevent this. The new 926 ignition control has a longer post purge time built in. Sometimes the problem with the swirl plate is that when the unit shuts off after firing, heat from the HX can migrate up and overheat the swirl plate causing it's early demise. The longer post purge helps remove more heat to prevent this. I have changed out all of my problem Munchkins to great results. A new 926 control also brings with it a higher voltage flame sensing circuit. It will also use the sparker as a 2nd flame sensor. No more F 09's. Yay! Say good bye to the 925 and install a 926. I also upgrade both refractories, target wall and burner door, along with a new burner gasket. Keep you Munchkin happy. Baby needs a new pair of shoes. WW
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