help with 220.82(c)

[aksparky]

I was asked to figure a load calc using the optional method for a 6500sq ft house that we are wiring. This home has a 20kw boiler that supplies in floor heat and the heating co. said he will be installing a 60 amp heat pump as well.
My question is, in 220.82(c)3 it says 100 percent of the heat pump compressor and 65 percent of the supplemental electric heat for central electric space heating systems. It just seems odd that I would consider the 20kw boiler as supplemental to a 14kw heat pump. Am I missing the boat altogether here or what?
Any help will be greatly appreciated.

 

[resistance]

You can omit the heat pump compressor, if the heat pump compressor does not operate at the same time as the supplemental heat.

 

[resistance]

To add. Note that 220.82 (C)(3) does not present what you wrote. See 220.82(C)(4)

 

[aksparky]

Thanks alot for your replys resistance,
I just got off the phone with the heating guy and he helped me better understand the system he is installing, he indicated the heat pump will come on if the 20kw boiler cannot keep up. Thanks again for the reply

 

[stickboy1375]

Thanks alot for your replys resistance,
I just got off the phone with the heating guy and he helped me better understand the system he is installing, he indicated the heat pump will come on if the 20kw boiler cannot keep up. Thanks again for the reply

Sounds like a 2nd stage heating system.

 

[haskindm]

Thanks alot for your replys resistance,
I just got off the phone with the heating guy and he helped me better understand the system he is installing, he indicated the heat pump will come on if the 20kw boiler cannot keep up. Thanks again for the reply

Seems to me that it should be the opposite. The 20KW boiler would come on if the heat pump could not keep up. But what do I know? Be interesting to understand the rational behind making the 20KW (that's 20,000 watts!) the primary system....