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Pulleys, motors, and horse power...

Timco
Timco Member Posts: 3,039
So I am servicing a large condo complex. Each unit has its own air handler.



Many have had their pulleys or motors replaced over the years to change the amount of air flow in winter to make less noise but that leaves them lacking in the summer for AC. These are hydro air coils in air handlers.



Question is, what is the correct process to check amps on phases to determine how many HP the motor is currently pulling (most in the building are 1/2 - 1 horse) and what pulleys I can swap to to get more air...like a 10 speed bike. Some 240v 2-phase, some 208 v 3-phase. Building is delta 3-phase.



Also, where do you measure a pulley to know its size? The shaft is easily measured with dial calipers but what about the belt side? Some are adjustable.



Many units need more air but I don't want to exceed the motor's capacity and don't want to go through the process of measuring all the ducts and air handler sizes since its all enclosed and build in 1960. No info plates on any air handlers, sizes differ from floor to floor with unit sizes.



Thanks! Happy 4th!!



Tim
Just a guy running some pipes.

Comments

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    edited July 2012
    Graingers...

    W W Graingers use to have this information in the back of their paper catalogs.



    They do have som information on their web site at http://www.grainger.com/tps/power_trans_chainguide.pdf



    and I am thinking that if you do a little research, you will find that they have more information available, just buried some place on their web site.



    Off hand, without having the manufacturers performance curves, and knowing what you need, its going to be tough to come up with the right combination. You may have to reinvent the wheel from scratch. You can find the maximum recommended amperage for the motor, but with adjustable sheaves and pulleys, there is no less than 1,000 combinations that will get you to the same point on the motor amperage curve, but all over the place as it pertains to air movement.



    As for checking amperage, what ever is listed is what you should see per pole. Its not an average (like your gut would think) nor is it an average. All legs should be within 10% of each other in voltage, and amperage. If not, you may have insulation breaking down on the motor windings, eventually causing motor failure.



    On a new FCU, the manufacturer has a RPM rating for their fan at a given pressure differential and subsequent CFM delivery. You set you sheaves to match that required RPM, then fine tune the adjustable sheave to keep the amperage within the motors specs.



    You've got your work cut out for you. Don't do it for free....



    Happy Independence Day to you too my friend.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Timco
    Timco Member Posts: 3,039
    Thanks and happy 4th!

    Yeah, I figured there would be more to this than just getting more air movement.



    The same procedure you described would check a motor and it's performance, right?



    Big job, 32 units. If cleaning the coil does not get air to all ends of the condos, then I want to increase fan speed. Some units really suffer and have little air at the register. As I mentioned, pulley sizes are all over the place so I need to know what combo to use for what motor size to fix these. The water / refrigerant side is perfect. Now the air handler side needs to be right.



    Thanks for the input,



    Tim
    Just a guy running some pipes.
  • Paul48
    Paul48 Member Posts: 4,469
    Ducts

    Are you losing a lot from leaky ducts?
  • Timco
    Timco Member Posts: 3,039
    Ducts

    I seal what I find leaking in the mech rooms, but the rest is 1960 tin in the ceiling. I doubt enough leakage to make this big of a difference. Some barely have any air at any vent and after cleaning the coils they either shoot tornadic chiled air or have some improvement but not what we want. Of course, those units have new motors with a different pulley than other units. I have the pneumatics working great.
    Just a guy running some pipes.
  • Techman
    Techman Member Posts: 2,144
    edited July 2012
    P,M&HP

    With only 32 units,how many different size AC's/condo's are there? You may have to check ,lets say, the entire 1st floor or condo 1-10 and compare what is there.What sq. ft. per condo is there? Ceiling heights? What size drive/driven pulley's? What size blower wheels? What H.P motor is common? KindaSorta wouldn't the motor H.P.stay the same even w/different phases and voltages(208-230vac) for a given size condo?An AC [email protected] 5tons is still 5t w/single or 2 or 3 phase or 208/230/460vac.As ME suggested,Grainger is good at helping w/ this.I would get 2-3 adjustable drive pulleys and start playing.The pulley is measured by it's O.D. and sized by the max/min adjustment of the adjustable pulley.For air flow and velocities and comfort, wouldn't 400cfm per ton still apply? KindaSorta wouldn't 1 sq.ft. = 1cu.ft. for a 1960 construction? 1200 sq.ft. is about a 3t load which is 1200CFM. You may also need several sizes of belts as you adjust the pulleys,or,I would get that "link belt" and add/subtract links until you figure the belt size required.
  • Timco
    Timco Member Posts: 3,039
    Sizes

    Thanks for more great input.



    10 stories. 1,2,3 floors are 4 units. 4,5,6 are 3 units. 7,8,9 are 2 units. 10th is all one unit.



    28 total.



    But the floors with 3 units are 1/2, 1/4, 1/4.



    1/4 units are 1000 sq'

    1/2 units are 2000 sq'

    Full floor is 4000 sq'



    All 8' ceilings.



    I would need to measure each blower and so on. That's why units that have reduced air when the coil is clean need more air, and thus a different ratio. Many run fantastic with a clean coil, and many still don't have the air they need for AC but since we install setback next heating season, the water temp is plenty hot enough to heat them with reduced air. They just suffer in summer.
    Just a guy running some pipes.
  • Techman
    Techman Member Posts: 2,144
    edited July 2012
    Timco

    SO ??!
This discussion has been closed.