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Posted: 7/4/2012 10:41:22 AM EST
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!
Link Posted: 7/4/2012 5:13:43 PM EST
[#1]
Quoted:
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!


You have single/split phase on the 240 units. A clamp on ammeter will give you a reading on current draw, not HP.

Is there anyway to swap out the blower motors with variable speed motors to customize CFM?
Link Posted: 7/4/2012 5:22:44 PM EST
[#2]
Quoted:
Quoted:
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!


You have single/split phase on the 240 units. A clamp on ammeter will give you a reading on current draw, not HP.
Multiply by 240. Divide by your power factor (the motor uses more than the meter shows). That gives you watts. Divide watts by 746. That will be HP.

Is there anyway to swap out the blower motors with variable speed motors to customize CFM?
This sounds like the right move. Direct drive, FTW.


Link Posted: 7/4/2012 5:26:48 PM EST
[#3]



Quoted:



Quoted:


Quoted:

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!




You have single/split phase on the 240 units. A clamp on ammeter will give you a reading on current draw, not HP.

Multiply by 240. Divide by your power factor (the motor uses more than the meter shows). That gives you watts. Divide watts by 746. That will be HP.



Is there anyway to swap out the blower motors with variable speed motors to customize CFM?

This sounds like the right move. Direct drive, FTW.




That going to give you a true HP Rating though?   It will tell you what kind of load you have on it, but it may only be running at half the motors HP capability.  





 
Link Posted: 7/5/2012 6:00:46 PM EST
[#4]
"True HP" is stamped on the nameplate.
Link Posted: 7/5/2012 7:08:01 PM EST
[#5]
Quoted:
"True HP" is stamped on the nameplate.


Yes, this I know. What I needed was the formula to monitor the motor load in HP as I change the fan speed with a variable speed drive pulley to get more air.
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