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  1. #1
    Join Date
    Mar 2011
    malone, ny
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    '86 Cantherm Duo520 -time for a new one?

    Hi guys!
    I'm sure glad I found this website!
    It's pretty cool!

    I have a major problem with a horizontally-installed loop Cantherm Duo520 GSHP system installed in my father's home located at the top of ice-cold New York state near the Canadian border in 1986 - it's down to one slab
    of heat left when it started with 4 sections originally.

    Two slabs were turned off about 10 yrs ago when
    they were no longer needed.
    One was for the outdoor backyard pool while the other was routed out
    to a dog-breeding kennel about the size of a 2-car garage.
    The 2 remaining slabs are for half of the home (bedroom & living/dining
    room areas)
    The other half of this ridiculously large single-floored home w/basement
    uses the Newton air exchanger for rotating the heated or cooled air.

    Now...only the master bedroom slab is working and the Newton is dead.
    No air moving at all...

    The blower doesn't turn on anymore and the pipe is really cold just as it reaches a large canister and before it enters the Duo520 unit.
    There are no lights on the Duo520 on and I hear a loud buzzing noise coming
    from the blower area of the unit.
    Where do I start?
    I have a Cantherm Duo520 manual but it's extremely minimal in information.
    There's absolutely no one within 50 miles of here that knows anything about it!
    The original installer was Neil Windsor Refrigeration and was certified by Cantherm out of Montreal, Canada - but he moved out to Colorado I think.

    Blower motor dead?
    Compressor dead perhaps?
    How come the master bedroom slab is actually working great?
    What can I check?
    I'd like to get at least the living/dining room area slab working again...please!

    I'm good with electrical, plumbing and know how to use a
    Refrigeration was never my forte...
    How can make sure the compressor is working correctly?
    I think it was changed out of the Duo520 about 9 years ago.

    I'm using the wood-stove for main heat right now but it is not sufficient enough heat to reach the bedrooms and
    bathroom at the other end of the house!
    I'm sorry this is my first post and it's too long already but I needed
    to give you guys some idea what's going on here.
    I'd appreciate it very much for help you guys can give me on this!
    I'm getting really sick of chopping wood in the


  2. #2
    Join Date
    Mar 2011
    malone, ny
    Post Likes
    Thread Starter
    I got a hold of Neil yesterday !
    He was very helpful and is going to try to dig up some info for me.
    I also located the original installer and will talk to them today.
    I wish I could of gotten more help from this forum on what to do
    but there wasn't a single response...
    Maybe you guys needed more info? I don't know.
    I'm disappointed really...
    In another website I belong to - we all help each other out as much as possible, especially when someone has a major problem.
    That doesn't seem to be the case here...

  3. #3
    Join Date
    Nov 2004
    SW FL
    Post Likes


    Quote Originally Posted by Bunker View Post

    I wish I could of gotten more help from this forum on what to do
    but there wasn't a single response...

    Maybe you guys needed more info? I don't know.
    I'm disappointed really...

    That doesn't seem to be the case here...
    Pages 58 to 68.

    There aren't too many that frequent this website that are 60+ Years old who might remember a specific CANTHERM model after 25 years.

    Your issues deal with a modified system IN A SPECIFIC ARRANGEMENT that NO ONE can respond to in a Meaningful manner without spending a SIGNIFICANT amount of research.

    You may just have to - just KNOW the Answer - before you begin.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  4. #4
    Join Date
    Mar 2011
    malone, ny
    Post Likes
    Thread Starter
    Thanks Dan!
    I was reading that interesting article about the Alaskan setup
    of a Cantherm Duo 500.
    Thanks for posting it up!
    It looks ancient doesn't it? lol

    I did some digging around and found some other stuff as well.
    I opened up the Duo 520 unit and discovered the problem.
    or should I
    Apparently there's a major leak of pinkish-colored glycol coming out of the heater coils just under the blower motor.

    I shut it down completely and I've also noticed that the leak happened to drip right onto the electric circulation motor now that appears to be shot as well.
    Tomorrow I'm going to pull out that motor and give it a good overhaul and see if it's repairable or replaceable.
    The main Duo520 compressor appears to be intact and I've found a receipt dating back to it being replaced about 7 years ago.
    The installer told me he changed that compressor and gave me some insight as to taking out the circulatory motor without spraying glycol all over the room. lol

    I am advised as to the steps I need to perform to bring the glycol lines back up to operating pressures.
    Remember, I have two complete unused slabs full of it! lol
    So there's no shortage of it around here.

    My only question remains is how to check to see if the glycol content/mixture is correct?
    If no one answers on how to do that - I suppose I
    can live with it at a 50/50 mixture...
    I'm pretty resourceful and can probably find out that answer myself.

    The cool thing is I got the dining room slab heat back on!
    Apparently some dumb-azzed plumber closed the valve.
    (It happens to be the same guy that said he'd changed it
    all out for an oil furnace for 15 grand...what a bloody crook ! lol
    I basically told him to get he hell outta here and go try
    and rip off some other old lady. )

    Anyways, so much for
    I opened it back up and looked around for leaks on various lines
    but found none other than the Duo 520 unit.
    I shut off the valves to those lines for now until I fix the leaks.
    The slab is getting it's heat from both the ground source and back-up auxiliary electric water heater for now.

    I'd love to post up some photos of this system for you guys
    but I don't know how to use this crappy forum software yet.

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