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  1. #1
    Join Date
    Feb 2009
    Posts
    6

    Munchkin Contender MC-50

    This is my first install ever!

    I'm a residential designer and (residential & commercial) contractor. A good friend of mine wanted a airplane hangar built. In an effort on his part to save a little dough, we did the install of the radiant ourselves. Figured I'd see where the cost of install is at. Now I know!

    I do have a question on this for those in the know? We have 3000SF with (12) 1/2" dia 250' zones. I cranked the system up to 75 degrees to see that all was running as it should. The max temp I ever get out of the boiler is 83 degrees? The system never made it to 75? What did I do wrong?





    Thanks,

    Karl
    Last edited by Haydin; 04-22-2009 at 03:49 PM. Reason: photo links

  2. #2
    Join Date
    Mar 2006
    Location
    NORTH HAVEN ,CT
    Posts
    87
    BOILERS TO SMALL AND WHATS UP W/THE TRAP IN THE PVC FLUE.

  3. #3
    Join Date
    Mar 2008
    Posts
    624
    how do you know its to small?

    doesnt that boiler have a condensate drain?
    HVAC PRO IN THE MAKING
    NATE's:
    Gas Heat Service/ Installation
    Air-to-Air Heat Pump Service/ Installation
    Air Conditioning Service/ Installation

  4. #4
    Join Date
    Feb 2009
    Location
    british columbia
    Posts
    94
    im with low pressure guy boiler should be at least 100.000 btuh and why is there a p-trap on vent isnt the boiler condensing it should have a drain at the bottom of boiler and if it cannot allow condensating water through the heat exchanger how well is the boiler made

  5. #5
    Join Date
    Mar 2009
    Location
    central illinois
    Posts
    532
    all the munchkins i put in had drain off the heat exchanger. have not seen that type. your drain looks a little strange. no balancing valves also you said you set at 75 and it went to 83 sounds like it is working.
    work to live not live to work.

  6. #6
    Join Date
    Feb 2009
    Location
    british columbia
    Posts
    94
    he set system t0 75 boiler temp only got to 83 i would love to know what return temp was on boiler and system side was while boiler was at 83 what was system temp.

  7. #7
    Join Date
    Mar 2007
    Location
    Madison, Wisconsin
    Posts
    2,260
    Pump sizing?
    Balance valves?
    Bypass to keep primary loop temp up?
    Who designed the loop layout?
    What is the building like, pad thickness, how deap did you lay the tube, insulation under the slab.....

    We need more info please.
    I r the king of the world!...or at least I get to stand on the roof and look down on the rest of yall

  8. #8
    Join Date
    Feb 2009
    Location
    british columbia
    Posts
    94
    its primary secondary no need for bypass unless youre going to put it on the secondary?

  9. #9
    Join Date
    Feb 2009
    Posts
    6
    Thanks for all the input!

    So tell me about balancing valves? Basically I went in to the supply house and got all the parts and built it according to the Munchin drawings. No mention of a balancing valve?

    The condensate drain is there. Just cant see it in the photo. I came out of the trap at the bottom of the unit and went through the plywood. That way the drain pipe is supported by the hole it runs through... make sense? You can see the main drain sloping to the right. The flue drain was on the drawing as an option. I figured it was about $2 in PVC so why not divert as much condensate as possible. The plastic line runs down into the top of the overflow TEE from the main condensate drain. The flue trap does catch a substantial amount of water.

    The unit does produce heat. It just runs 24/7. It makes it to within a few degrees of what is set on the thermostat. Just wondering if these little guys are supposed to run constant?

    Haydin

  10. #10
    Join Date
    Feb 2009
    Posts
    6
    Quote Originally Posted by Wheelbaron View Post
    Pump sizing?
    Balance valves?
    Bypass to keep primary loop temp up?
    Who designed the loop layout?
    What is the building like, pad thickness, how deap did you lay the tube, insulation under the slab.....

    We need more info please.
    Some of the design parameters that I know:

    pump sizing: is this the amount of liquid moved? The pumps are grundfors with integral check valves and LOW/MED/HIGH speed switch.

    balancing valves: Gotta figure out what those are.

    bypass to keep primary temp up: The manifold is per Munchkin design drawings. The primary loop recirculates at the closely spaced tees. Note the supply and return from the boiler lines go vertically up to the first horizontal line. This is where the floor loop picks up its warm water. The tee width is, according to the manual optimal at 4 times the pipe diameter. I used 1 1/4" pipe so 5" center to center.

    Loop layout is per Munchkin manual: w-w-w.htproducts.com/literature/lp-171.pdf
    I used the system on page 29&30. Or are you referring to the ground loop? I did all the ground loop layout. I laid alternating supply and return lines next to each other.

    The building is a 50' x 60' (3000 SF) with average 11' ceiling height open steel building with R-19 insulation in Ogden, UT. The slab is 4-5" thick. The loops are 12" on center on 1/2" styrofoam insulation. I used 1/2" dia oxygenated pex line tied to WWM. The concrete was poured on top of the insulation and ground loops. Here's a shot of the beginning.



    Thanks,

    Karl

  11. #11
    Join Date
    Feb 2009
    Posts
    6
    Quote Originally Posted by viessmann View Post
    he set system t0 75 boiler temp only got to 83 i would love to know what return temp was on boiler and system side was while boiler was at 83 what was system temp.
    The return temp to the boiler was at 68 degrees when the supply was at 83 degrees.

  12. #12
    Join Date
    Feb 2008
    Location
    Altmar, New York, United States
    Posts
    4,652
    you realy need to get a pro to look at this. do you know the flow rates you need for the loops? what is the surface temp on the floor? has the boiler been set up using the proper instruments? do you have the tools needed to set this boiler up? you have it working why not pay to have it working right. it will save you in the long run. are you a builder or a home owner? i could go on all day, just call a pro.

  13. #13
    Join Date
    Jun 2007
    Location
    Minneapolis, MN
    Posts
    734
    I know this is an old post but still a recurring theme. So...

    This is how products like the venerable Contender get a bad name.

    Before you buy a boiler, you might:

    1. Evaluate the available fuels.
    2. Have a proper heat load analysis (specific to radiant heating) performed by an experienced professional, who will not miss the lack of proper insulation below the slab for example.
    3. Determine the type of radiation you will use and have said professional layout the barrier tube, size and length per loop.
    4. Consider zones (an area controlled by a thermostat) and the loops (a continuous piece of pipe originating and terminating at a manifold) before starting. CAD layout is a great help here.
    5.Read, understand and follow the manufacturer's installation manual before ordering the boiler.

    If you had followed the five easy steps noted above you would have all of the answers to your questions before you started the project.

    Any vendor of equipment should be able to help you with design and layout, but if they can't, it is time to find a new vendor.

    If a boiler operates 24/7 in design conditions (the coldest 5 days of the year) and satisfies the thermostat, it is perfectly sized to the load.

    There are many here and elsewhere who can help you before you get started on your next radiant floor project, Radiant Panel Association membership and a NATE boiler certification while your at it.

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