HVAC Load calculation

[SMB]

What is the proper way to determine the HVAC load in kW of an HVAC unit? The firm I work with states a rule of thumb is 2kW per ton.

Thanks for all replies.

Steve

 

[stickboy1375]

The nameplate is the ONLY way.

 

[SMB]

If you have no name-plate and are estimating based on tonnage, what would be the best way?

 

[LarryFine]

If you have no name-plate and are estimating based on tonnage, what would be the best way?

Phone call to manufacturer. If you have a rule-of-thumb to use, use it. I've heard from 1Kva/ton to 2Kva/ton.

I insist on customer (or HVAC supplier) providing nameplate info, or paying me to wire for worst-case estimating.

I'd hate running #6 for a unit than ends up only needing 20a, but someone's gotta pay if they can't provide info.

 

[SMB]

Larry, thanks for the input. At this time, my customer is undecided on a unit. I will use the 2kva per ton rule of thumb as worst case. Once we determine the unit, I will get nameplate data. When looking at nameplate data, what is used to determine the kva rating? I would assume V x I x 1.73 for 3-phase or V x I for 1-phase. Is this the correct approach?

Thanks again.

Steve

 

[tryinghard]

Larry, thanks for the input. At this time, my customer is undecided on a unit. I will use the 2kva per ton rule of thumb as worst case. Once we determine the unit, I will get nameplate data. When looking at nameplate data, what is used to determine the kva rating? I would assume V x I x 1.73 for 3-phase or V x I for 1-phase. Is this the correct approach?

Thanks again.

Steve

Check out 440.4(B), "Multimotor and combination-load equipment shall be provided with a visible nameplate marked with the maker's name, the rating in volts, frequency and number of phases, minimum supply circuit conductor ampacity, the maximum rating of the branch-circuit short-circuit and ground-fault protective device [breaker]..."

If the lable isn't there the unit may not be listed.

Check out the following:
Unit Multiplied by Converted Unit
refrigerative ton 3,516.852 842 watt
refrigerative ton 3.516 852 842 kilowatt
refrigerative ton 4.714 279 949 horsepower
refrigerative ton 12,000 BTU/h

Also:
Unit Multiplied by Converted Unit
kilowatt 1000 watt
kilowatt 1.340 482 57 horsepower
kilowatt 0.284 345 14 refrigerative ton
kilowatt 3412.142 45 BTU/h