Spilt system????

[nathan]

Would a heat pump that not only heats but doubles as an air conditionor fall under the 440-4b code for brach circuit calcs. Ive been told it is thought of as a split system therefore it is only neede to be sized to the nameplate without the 125%.

 

[websparky]

Re: Spilt system????

NEC 2002 440.4(B) Multimotor and Combination-Load Equipment. 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, and the maximum rating of the branch-circuit short-circuit and ground-fault protective device............

For a typical heat pump, the rating plate is the answer. As far as a spit system, a typical residential a/c or h/p is a split system in terms of HVAC language, not NEC language. An HVAC system that is not a spit system would be a commercial style roof-top unit where the condenser, compressor, evaporator and blower is all in one unit.
440.4 (A) refers to a compressor only, which is typical of a large commercial a/c system found in your local Wal-Mart or shopping mall.

Hope this helps!
Dave

 

[nathan]

Re: Spilt system????

Thanks Dave, it does help. So tell me please if I have this correct...if you need to apply any more amperage to your branch circuit calc when sizing and air-conditionor or heat pump it should say on the nameplate from the manafacturer. As what I see in 440.4(C).

 

[websparky]

Re: Spilt system????

You are welcome!

The manufacturers follow NEMA code and the rating plate must contain "max" and 'minimum" circuit breaker (hvar type if no fuse at the disco)or fuse size which takes into account the NEC requirement for 125%.