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  1. #1
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    A little lost here.... DOE 2018 Energy Regulations

    I have 2, Carrier 50TC-D30's with socks. These two RTU's run 24/7 (blowers never shut down). I am adding two more of the same, but with the new Regs. require a VFD or Two-stage fan on cooling units 65,000 BTU/h or larger... How do I setup the blowers on the new units, I have a fixed CFM/Static pressure?

    Thanks guys, Bob.
    GET OUT OF THE HOUSE.....

    Build a boat, go for a hike, ride a bike, how about a walk....

  2. #2
    Join Date
    Aug 2002
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    Just set the speed drive to run continues.

  3. #3
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Just set the speed drive to run continues.
    Ya, that's what I was going to do... Just the cost of the VFD.... wiring.... controls....
    GET OUT OF THE HOUSE.....

    Build a boat, go for a hike, ride a bike, how about a walk....

  4. #4
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    Quote Originally Posted by Capt Wolf View Post
    Ya, that's what I was going to do... Just the cost of the VFD.... wiring.... controls....
    Several advantages with speed drives.............

    Electrical Protection, Soft Starts, less wear & tear on belts sheaves blowers, fully adjustable to the particular job.

  5. #5
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    Apr 2017
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    strange rule man. are you sure there is not an exception for constant load stuff like process cooling?

    vfd for fixed speed stuff just seems wrong... doesnt the vfd loose like 5% of the input power to heat or something anyway? I work with centrifugal and PD compressors fairly often... if the client is not varying the load with a control system we always just go with new pulley sheaves for turndown or throttling the blowers.

    i wonder if you would be allowed to wire the VFD like a soft start box? IE cut out to line voltage after it reaches its RPM at 60hz.

  6. #6
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    Jan 2015
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    Quote Originally Posted by queequeg152 View Post
    strange rule man. are you sure there is not an exception for constant load stuff like process cooling?

    vfd for fixed speed stuff just seems wrong... doesnt the vfd loose like 5% of the input power to heat or something anyway? I work with centrifugal and PD compressors fairly often... if the client is not varying the load with a control system we always just go with new pulley sheaves for turndown or throttling the blowers.

    i wonder if you would be allowed to wire the VFD like a soft start box? IE cut out to line voltage after it reaches its RPM at 60hz.
    A VFD can make a huge difference. I got to rough in a Johnson Controls VFD for a 15hp pool pump. Before the pump ran at 60hz and pulled 11kw per hour. With the VFD I only had to run the pump at 52hz and reduced power consumption down to 5kw per hour. They can dramatically reduce energy consumption but they are rather expensive to replace. I think that particular unit was around $1200 for the part. However in commercial it would pay for itself in a short time.

  7. #7
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    Quote Originally Posted by James Colver View Post
    A VFD can make a huge difference. I got to rough in a Johnson Controls VFD for a 15hp pool pump. Before the pump ran at 60hz and pulled 11kw per hour. With the VFD I only had to run the pump at 52hz and reduced power consumption down to 5kw per hour. They can dramatically reduce energy consumption but they are rather expensive to replace. I think that particular unit was around $1200 for the part. However in commercial it would pay for itself in a short time.
    yea i get what you mean. Especially with direct drive stuff where there are no pulley sheaves to swap.

    is he going to be reducing the load though? sounded like they were cooling some constant process and would be running at design capacity constantly.

    Im sure you know this... but you can achieve very good turn down and energy savings with new pulley sheaves. it depends on how much the motors "like" vfd's, but at worst its almost as good(with respect to power costs) as static throttling with a VFD when you consider the internal losses within the VFD and replacement costs every 10 years or so.

  8. #8
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    Buy VFD. Don't install VFD. Everybody happy.
    Don't step on my favorite part of the Constitution just to point out your favorite part.

    Political Correctness is forced on you because you have forgotten decency.

  9. Likes queequeg152 liked this post

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