Calculating loads for "heat pumps"

[acrwc10]

I don't work on many houses where heat pumps are used because natural gas is available in our area. Right now I am sizing a service for a 7700 sq. ft. house and they are proposing 3 heat pumps. each heat pump has an RLA of 30 amps 240 and an inside unit that is 4.3 amps with a 10,000 watt heat strip.
They also have a sauna, that is 10KW. a steam room that is 8KW watts, 3 exterior heaters that are 4,000 watts each.
the kitchen has 2 ovens 6.3KW and a dual fuel range that is 11.5KW
The lighting load is about 97 amps.

would you calculate all the heat pumps, sauna, steam room and exterior heaters to be on at the same time? And how about the kitchen loads?

My approach is to assume that at some point all the lighting could be turned on, maybe a party, and all the heating and saunas could be used at one time. ( just thinking of Jim in Tampa) but not all of the kitchen appliances.

I should add I tend to go over what the NEC requires for service sizing just to be safe.

 

[kwired]

I don't work on many houses where heat pumps are used because natural gas is available in our area. Right now I am sizing a service for a 7700 sq. ft. house and they are proposing 3 heat pumps. each heat pump has an RLA of 30 amps 240 and an inside unit that is 4.3 amps with a 10,000 watt heat strip.
They also have a sauna, that is 10KW. a steam room that is 8KW watts, 3 exterior heaters that are 4,000 watts each.
the kitchen has 2 ovens 6.3KW and a dual fuel range that is 11.5KW
The lighting load is about 97 amps.

would you calculate all the heat pumps, sauna, steam room and exterior heaters to be on at the same time? And how about the kitchen loads?

My approach is to assume that at some point all the lighting could be turned on, maybe a party, and all the heating and saunas could be used at one time. ( just thinking of Jim in Tampa) but not all of the kitchen appliances.

I should add I tend to go over what the NEC requires for service sizing just to be safe.

Will back up heat strips be able to operate at same time as heat pump? If not use the larger load which should be the heat strip. Blower runs either way. Otherwise use allowable demand factors in 220. Unfortuneately 222.51 says to use 100 percent of fixed electric space heating.

I wouldn't call a sauna fixed electric space heating. It is a considerable load but is not used the same way as other heating. I still may consider it at 100% though. It is used hard when it is used.

Not mentioned in code but if having a party heating loads generally get a break. All the bodies put off heat as well as any appliances that are being used.

I've seen places that have to run cooling even when it is cold outside when there is a lot of people there or other heat generating activity going on.