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  1. #1
    Join Date
    May 2007
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    13

    ECM or PSC blower for zoned WaterFurnace Legend?

    I've got an open-loop 6 ton WaterFurnace Legend at a summer house in Northeast Pa.

    I'll use cooling maybe a week a year. I keep the heat at 55-60 during the winter, except for 4-6 vacation weekends.

    There are two zones. My contractor has told me that we should use a PSC blower. He says an ECM blower won't work with the WaterFurnace zone system. As the zone system balances the supply air the ECM blower will try to rebalance it, creating a feedback loop. In addition, he says the ECM blower would not be cost effective ($0.14/kwh).

    This doesn't sound right to me. I'd appreciate any help.

    sean

  2. #2
    Join Date
    Jun 2007
    Location
    Greenwood Indiana (Indianapolis)
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    420
    In order to receive your 30% tax credit, I am pretty sure you will have to chose the ECM motor. Even not, I would still chose it.

    He has the 2 motors reversed. The psc motor uses the most energy for sure. The ecm motor hardly uses any power at all.

    This must be 1 big house, 6 tons is large!, especially zoned.
    As iron sharpens iron so one man sharpens another Proverbs 27:17 NIV84

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,601
    I'd want the ECM blower. The X13 is the standard motor for that unit. the PSC is an optional motor.
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  4. #4
    Join Date
    Sep 2009
    Location
    Arnold mo
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    If the contractor has a proven track record with zoned systems and with the equipment he is installing, I would listen to someone who has expertise in that area. An ECM motor is more energy efficient when it is running in "circulate only" mode, so the cost effectiveness of the motor is not as great when compared to a PSC motor operating only during calls for heat or cool. Have the contractor back his words up in a good warranty and you should be good to go.
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  5. #5
    Join Date
    May 2007
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    13
    It's not really a warranty issue. I assume both will work, though interestingly the WF site says that an ECM motor has an expected life of 15-18 years, compared to PSC of 10 -12. But, as I said, this is not the issue.

    Has anybody used ECM with a zoned system? Does the zone controller "chase" the ECM motor?

    I'd expect to leave the motor on all the time. Cathedral ceilings, so I'd like to keep air circulating.

    What sort of price difference between ECM and PCS? Is there any? Can one motor be switched for the other once installed?

    sean

  6. #6
    Join Date
    Sep 2009
    Location
    Arnold mo
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    Here is something I found regarding this matter. Hopefully some zoning experts will chime in.
    http://www.ewccontrols.com/zoning_an...able_speed.htm
    An answer without a question is meaningless.
    Information without understanding is useless.
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  7. #7
    Join Date
    Feb 2009
    Location
    Portland OR
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    2,029
    Quote Originally Posted by beenthere View Post
    I'd want the ECM blower. The X13 is the standard motor for that unit. the PSC is an optional motor.
    PSC motor is standard on legend units with an upgrade option to high static PSC or to a 5 speed ECM a.k.a X13.
    WaterFurnace has the intellizone system which can modulate the ECM blower based on the percentage size of the zone calling for heat. I have never installed a legend unit so I am not positive the intellizone system works with the 5 speed ECM, but i know it does work with the ECM 2.3 motor(variable speed motor on 5 series).
    Personally I would upgrade to a dual capacity series 5 with an AXB and install the intellizone two system. The intellizone 2 is a communicating zoning system that will control blower motor(about 12 stages of blower capacity) and compressor based on how much heat/cooling is needed in each zone. It also has energy management features and can be remotely controlled via the Aurora Web Link(a future release)
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  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,601
    From WF' web site on the legend.

    BLOWER MOTOR: A 5 speed X13 ECM blower motor allows the unit to provide precisely controlled comfort, quiet operation and energy savings. (PSC motor available).

    I never seen one, so i don't know.
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  9. #9
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
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    Quote Originally Posted by seandarcy View Post
    I've got an open-loop 6 ton WaterFurnace Legend at a summer house in Northeast Pa.

    I'll use cooling maybe a week a year. I keep the heat at 55-60 during the winter, except for 4-6 vacation weekends.

    There are two zones. My contractor has told me that we should use a PSC blower. He says an ECM blower won't work with the WaterFurnace zone system. As the zone system balances the supply air the ECM blower will try to rebalance it, creating a feedback loop. In addition, he says the ECM blower would not be cost effective ($0.14/kwh).

    This doesn't sound right to me. I'd appreciate any help.

    sean
    The ECM motor is the only way to go. It will only "ramp" (chase) up or down with a barometric by-pass.

    If you use a modulating by-pass you'll be fine.

    Your contractor doesn't know what he's talking about, which scares me regarding his knowledge on ductwork. That's a whole different issue.

    It's a good thing you asked (here) to fine out the real story before you regret it for a very long time. ECM motors are more reliable, energy efficient and quieter.

  10. #10
    Join Date
    May 2007
    Posts
    13
    This is it. He's installing a barometric bypass. I had no clue that made any difference. And, he installed the barometric bypass yesterday!

    Is it difficult/costly to change a barometric by-pass to a modulating by-pass? What is the difference, and why would one want one over the other?

  11. #11
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
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    2,744
    Quote Originally Posted by seandarcy View Post
    This is it. He's installing a barometric bypass. I had no clue that made any difference. And, he installed the barometric bypass yesterday!

    Is it difficult/costly to change a barometric by-pass to a modulating by-pass? What is the difference, and why would one want one over the other?
    A baromatric by-pass will work okay with a PSC or X13 motor. If your system has a ECM motor (blower), then a modulating by-pass is needed so it won't "hunt" for the right airflow.

    To change it is only possible if the zone control board will allow it.

  12. #12
    Join Date
    Sep 2009
    Location
    Arnold mo
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    3,977
    Hey George2, can you clear that up a bit. Sounds like you are saying a modulating by-pass is needed with an ecm motor but not with a x13 motor; but the x13 is an ecm motor.
    An answer without a question is meaningless.
    Information without understanding is useless.
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  13. #13
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
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    Quote Originally Posted by tipsrfine View Post
    Hey George2, can you clear that up a bit. Sounds like you are saying a modulating by-pass is needed with an ecm motor but not with a x13 motor; but the x13 is an ecm motor.
    I'll try to make it understandable.

    A X13 motor is a constant torque motor. When the ESP increases, the airflow will decrease (like a PSC motor), but the torque is not effected as much as with a PSC motor.

    When the ESP increases (as with zoning or a dirty filter), the ECM motor will automatically increase the airflow.

    Thus, with a barometric (weighted) damper, the airflow will go up and down ("hunting" for the right airflow) with a ECM motor.

    I hope that helps a little. There is probably more on this if you visit the Arzel zoning website.
    That's how I learned some of this. Another source for me was www.achrnews.com

    Enjoy!

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