Another Load Calc Question

[steve66]

There are some apartments, and each apartment has a furnace with a 10KW electric heat pack.

It gets cold here, and that is really the only heat for the entire apartment.

Looking at 220.82(C), it looks like this should be calculated per #4 - 65% of the nameplate rating of electric space heating where there is less than 4 separately controlled units.

But I'm not sure about #6: 100% of the nameplate rating for electric thermal storage and other heating systems where the usual load is expected to be continuous at the full nameplate rating.

It seems like only the HVAC designer would know if it was intended to be continuous at full load.

So #4 or #6?

 

[Tulsa Electrician]

Couple questions first.
Voltage
Wire type 60c or 75c
Any other load in Furnace like motor etc.

Your asking for wire size yet doing a load calculation based on 220
Are looking for service wire size or branch circuit to the unit.
Based on the #6 I would think your looking for branch circuit in each unit to the furnace unit which takes you to 424 and no 65%.

You may be asking two questions which I ran together. If so sorry.

 

[tortuga]

There are some apartments, and each apartment has a furnace with a 10KW electric heat pack.

is that the primary heat no heatpump?

It gets cold here, and that is really the only heat for the entire apartment.

Looking at 220.82(C), it looks like this should be calculated per #4 - 65% of the nameplate rating of electric space heating where there is less than 4 separately controlled units.

Thats what I do

It seems like only the HVAC designer would know if it was intended to be continuous at full load.

If a 10kW heat strip needs to run non stop to keep the unit warm it would probably be a energy code violation or the tenant vacate after they got their first winter electric bill.

 

[steve66]

Couple questions first.
Voltage
Wire type 60c or 75c
Any other load in Furnace like motor etc.

Your asking for wire size yet doing a load calculation based on 220
Are looking for service wire size or branch circuit to the unit.
Based on the #6 I would think your looking for branch circuit in each unit to the furnace unit which takes you to 424 and no 65%.

You may be asking two questions which I ran together. If so sorry.

My bad. When I asked about #4 or #6, I meant the code paragraph (4) or (6), not a wire size.
It was really just a load calc. question - should the heat pack be counted at 100% or 65%?

 

[steve66]

is that the primary heat no heatpump?

Thats what I do

If a 10kW heat strip needs to run non stop to keep the unit warm it would probably be a energy code violation or the tenant vacate after they got their first winter electric bill.

No, it looks like its an air handler with electric heat, and just a standard condensing unit.

They are older, probably installed before heat pumps really became a thing.

 

[wwhitney]

So you are just calculating the feeder load for one apartment, rather than the service load for all the apartments?

Electric forced hot air is definitely number paragraph (4), not (6). An example of paragraph (6) would be say a system to use cheap overnight electric rates to heat stored water, and then use the heated water during the day to provide space heat.

Cheers, Wayne