many nameplates will have a list of possible heat strips to be installed and the installer is supposed to mark which heat strip has been installed.
The nameplate will usually tell you requirements for supply circuit based on which heat strip is marked as the one installed.
You not only have 20 kw x 125% you also must add in the blower.
I sure hope this is not a house. Ouch what a bill
the bill depends on where you live. 20kw furnaces are very common around here(Nebraska). Electric rates are favorable for electric heat here, utility demand in winter is low. Winter rates are lower than summer rates, and rate usually is bracketed so first XXXX kw/hr are at $.XXXXX next XXXX are at $.XXXXX, and then anything over XXXX is at $.XXXXX.
cant tell you what the X's are right now.
You not only have 20 kw x 125% you also must add in the blower.
I sure hope this is not a house. Ouch what a bill
424.22(B) does apply.
Art 220 is for calculating the load. You have to refer to the applicable Codes for the actual wiring. 424.5 specifies 125%
All heat pumps, by Code, should have a nameplate giving you specifics on the branch circuit wiring including the min ckt amps and max overcurrent and how many circuits are needed.
On some units the heat and compressor can run simultaneously.
The manufacturer data (424.28, 440.4) is a requirement and is there to give you all that info.
In this jurisdiction, the job woud not be approved without the required data plate.
This is a heat Pump. The 20kW is supplemental heat. It does not run all the time, only when it need it.
The data plate does give MCA, but its does not include the electric heat because it is optional. In Florida you might only install a 10KW heater in it, but up north the same heat pump might require a 20kw heater.
By the way, for some reason my copy of NEC does not have 424.5 After 424.3 it jumps to 424.6
In most heat pumps, it will run the full 20KW when doing a defrost. It will also run some or all of the heat strips when the outside temperature is cold enough that the heat pump can't keep up (typically around 30 to 35F, and the colder it gets the less heat the heat pump can generate).
The article 220 thing is for Service and feeder calculations. The branch circuit size is dictated by 424.22.