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  1. #1
    Join Date
    May 2020
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    Question A QUEST TO FIND BIG UGLY ROOF TOP UNITS

    I'm scouting project sites for deployment of a new RTU retrofit solution that saves a ton of energy in these beastly machines. Any help from the forum on target sites would be greatly appreciated. I know they are out there. 60% of commercial HVAC is served by packaged roof top units. Also looking for an install partner who can help with deployment.

    RTU Site Search Criteria:

    Location: Anywhere in North America
    Unit Size: 6 - 40 Ton RTUs
    Unit Quantity: 30 Units or Above per Site
    Why am I doing this: Because I may get fired if I don't succeed in finding them

    Please help!

    Thanks

  2. #2
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
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    The only units you can do a reasonable evaluation on with the given information is penthouses with usually 6 resi type (commercial) AHU'S. They save a lot of energy if properly designed and TAB is done. They are usually limited to 5 tons per AHU but could be more depending on the situation.
    Your post doesn't mention exhaust heat recovery capabilities or any other potential method of recovering energy. Without that information your guess is as good as ours.
    No man can be both ignorant and free.
    Thomas Jefferson

  3. #3
    Join Date
    Nov 2011
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    East Side
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    is this that same energy management control retrofit from a few years ago, where you cycle the compressors and fans on and off to shorten the amount of "on time"?

  4. #4
    Join Date
    Apr 2010
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    Texas
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    Many places that meet your requirement would be national accounts like Home Depot, Lowes, Bed Bath and Beyond, Sams, places like that.

    Most of them already have salesmen and energy management consultants constantly calling trying to use them as guinea pigs to save money, which is pretty important when you have these huge stores all over the country.


  5. #5
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
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    Every store I did TAB on that had national account control systems were screwed up. The control guys tried to tell me on every job how much outside air to provide.
    I did one store that at zero ambient and design outside air CFM the heating air temperature calculated to 46 F. I called the engineer and told him he had a problem. He said "You don't understand we did a value engineering study on this building". He didn't understand they couldn't heat the office space when it got close to zero. For some reason they called me to fix it. All they had to do was look at the balance report with the calculations to see that TAB couldn't help them.
    No man can be both ignorant and free.
    Thomas Jefferson

  6. #6
    Join Date
    Apr 2020
    Location
    Garner NC
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    I mainly know about Novar and NexRev controls systems for main building controls..programmed for unocp and ocp for the energy savings

  7. #7
    Join Date
    Nov 2011
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    East Side
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    someone came on here a few years ago introducing a revolutionary new control system for old RTU's that promised huge energy savings. there was only one or two people that responded having any experience with them.....said it was great, etc. etc.


    turned out the controls actually cycled the motor's supply voltage at a very fast rate.....like an SCR cycles heat strips. the claim was that the motor wasn't powered for say 50% of the time it was on, so it saved 50% electrical usage. can't remember the details, but that was basically the explanation.

    no one ever came back to tell us if motor life was shortened, or if there were motor failures in areas with dirty power, etc. the energy savings fell into the category of sounding too good to be true......

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  9. #8
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    Not to say that creative innovation can’t happen, however, manufacturers scrimp and pinch to get every energy dollar out of their units. While some will sacrifice energy savings in the name of first cost, if they could save BIG energy, wouldn’t that give them such a competitive edge as to destroy their competitors? So, wouldn’t that have already done it?

  10. #9
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
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    jayguy the search for more efficient equipment is an ongoing thing for the reason you stated "competitive edge". Not all ideas work or may work under certain conditions but are a bad idea for the long haul. The main missing component I have seen is life cycle cost analysis. It is not perfect but in many cases will tell you whether the venture is worth while.
    One of the best ways to most efficiently use HVAC energy in commercial buildings is controlling outside air with a combination of building static pressure control and CQ2 control. I convinced an engineer I consult with to try it and the results on some of the buildings was beyond expectations.
    How often do any of you see that control method used?
    No man can be both ignorant and free.
    Thomas Jefferson

  11. #10
    Join Date
    Apr 2020
    Location
    Garner NC
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    i also make sure the economizers are fully functional for more energy savings...the buildings are also rechecked to size the new unit properly for the space, many old 2 compressor r-22 units are being swapped for 1 comp r-410a units with reheat....personally i like the 2 comp units, this way if 1 comp fails you have the other..every little bit helps..

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