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  1. #1
    Join Date
    Jan 2010
    Location
    Stamford, CT
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    14

    PCM to ECM? Worth It?

    Hi guys. First post and hope you have some feedback.

    Customer wants to investigate the possibility of saving energy with his existing furnace (circa 1992). He is looking to upgrade his Thermo Pride OH16-125 furnace blower motor (PSC-Type) with a Genteq Evergreen AF or IM ECM motor. I have read the standard sell sheets that claim this motor will operate at 73% less wattage than the standard PSC motor. Right now, the system operates in a single speed setting.

    This furnace is used for HVAC, and we recently replaced the evaporator and condenser with a Carrier Infinity Puron system. The whole thing is controlled with a Carrier Comfort Zone II system (5 zones).

    Question for the group is if anyone has ever 'upgraded' a furnace like this with just an ECM motor? If so, has it resulted in anywhere close to the energy savings purported by the ECM sell sheets? The rest of the Thermo Pride furnace is in great shape, and I would hate to shock him with a story that he would need to rip it out and replace to save him energy.

    Thoughts?

  2. #2
    Join Date
    Jun 2003
    Location
    Jacksonville, FL.
    Posts
    4,313
    Why not just replacing the whole furnace with a Carrier Infinity furnace?
    WHY?

  3. #3
    Join Date
    Jan 2010
    Location
    Stamford, CT
    Posts
    14
    Quote Originally Posted by Special Ed View Post
    Why not just replacing the whole furnace with a Carrier Infinity furnace?
    For starters its an Oil Fired system. There is no gas available in the area. The system was repaired about 2 years ago and he didn't want to do the whole thing (it is also a very tight space install). Now he is looking to cut as much electricity usage as possible (short of not using any at all..). Plus the Thermo Pride is still a good furnace.

  4. #4
    Join Date
    Jan 2004
    Location
    PA
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    68,769
    Quote Originally Posted by Special Ed View Post
    Why not just replacing the whole furnace with a Carrier Infinity furnace?
    No Infinity furnace is as good as that Thermopride.

    It will be around after any Infinity installed today has rusted away.
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  5. #5
    Join Date
    Jan 2004
    Location
    PA
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    Doubt you'll save 73%.

    Depending on duct system. may not save anything.
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  6. #6
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    6,051
    The evergreen claims 74% less watts - - comparing just a G call (fan only) compared to the new Low low G call speed. They are marketing this to anyone with air cleaners, uv lights, and zoned systems saying that by leaving the fan on you get greater comfort and IAQ. The watts in cool speed and Heat are 25% less still. Also the Evergreen motor will provide more constant CFM in cool as well as adding a dehum capabilty very easily. Hope this helped.

    It is a true ECM motor. It does not have a low voltage board. It uses line voltage "speed tap" selectable profiles. I just got all their literature in the mail to start selling them but havent installed any yet to be able to know their pros and cons first hand.

  7. #7
    Join Date
    Jan 2010
    Location
    Stamford, CT
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    14
    Quote Originally Posted by beenthere View Post
    Doubt you'll save 73%.

    Depending on duct system. may not save anything.
    Granted, duct efficiency certainly plays a part, but I can't help but think if the PSC motor (at speed) is using about 250W, then a ECM motor at same RPM) would only be using 150W. Reduced wattage = lower kWh = lower cost...right?

    I am just talking energy consumption of the motor only. The blower wheel and everything else would remain the same...

  8. #8
    Join Date
    Jan 2004
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    PA
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    The PSC set at high speed might be spinning at 1075 and only moving 80% of the air that it is suppose to.
    The ECM set to move the same amount of air, will increase its speed in an attempt to move that air. So it may6 be spinning at 1300 RPM.

    The higher the static pressure an ECM works against. The faster it spins to move the air its suppose to.
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  9. #9
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,763
    I installed one of the thermopride upgrade ECM motors. Not been in long, so not sure about energy use. Dramatically improved duct work also, spray foamed basement, and ho heats significantly with wood-so huge variables involved. Ho now runs fan continuous, so if electric goes up much that I will know.

    Thought propane furnace made more sense but ho wanted to keep his battleship.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  10. #10
    Join Date
    Nov 2004
    Location
    NJ
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    1,205
    Quote Originally Posted by LJSMITH1 View Post

    Thoughts?

    If they ever run the fan on "on" no question it's worth it. If not you'd have to look at run time etc. to see if it's got a positive ROI.


    Quote Originally Posted by beenthere View Post
    The PSC set at high speed might be spinning at 1075 and only moving 80% of the air that it is suppose to.
    The ECM set to move the same amount of air, will increase its speed in an attempt to move that air. So it may6 be spinning at 1300 RPM.

    The higher the static pressure an ECM works against. The faster it spins to move the air its suppose to.
    The Evergreen ECM the OP is referring to is a constant torque motor just like a PFC, not a variable speed ECM. So it won't speed up in an attempt to move more air. It's blower curves looks pretty much the same as PSC and not a flat line like a vari speed.

    They do use less power than a PSC moving the same CFM, and shine just like a variable speed ECM when they run on that low RPM constant fan.


    The motors go like this:

    Good - better - best
    PSC - ECM constant torque - ECM variable speed
    PSC - X-13 - variable speed
    PSC - Evergreen - Think Tank 2.0 2.3 3.0
    Ed J

  11. #11
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,763
    k - guys - that's over my head. Not sure the HO is going to get it.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  12. #12
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,769
    Quote Originally Posted by tedkidd View Post
    k - guys - that's over my head. Not sure the HO is going to get it.

    The OP is suppose to be in the trade.
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  13. #13
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,763
    Paint me with the stupid brush. I'm ok with that.

    Let's move this to the pro section, then dumb it down for ME!!
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

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