Demand water heater

[alphabraxon]

Im currently designing the load panels fora series of condos. The developer is considering going with demand electric water heaters. Were looking at a 10.8kw 208 volt 1 phase model. In the dwelling unit load calcs do I simply substitute the water heater entry with demand water heater at 10800 VA?

Does NEC have anything specific on it? Any help or advice would be greatly appted.

 

[charlie b]

The code does not require you to include an electric water heater in the load calculation, unless of course you know there will be one. This is different, for example, then the laundry circuit, which you most often have to include even if the owner does not plan to buy a washing machine. So it is not a matter of substituting one type of water heater for the "standard type that normally goes into the calculation." I would apply 220.14(A), and count the 10,800 VA as you suggested. I would not apply 422.13, as this is not a storage type water heater.

 

[alphabraxon]

Sorry

Yes we are using water heaters. But originally they were thinking LP tanked water heaters. Because of delivery of LP gas and other reasons decided to go electric then to demand electric. Any thoughts as to tanked over demand? From electrical point of view.

 

[charlie b]

Not sure I understand. If they used a gas-fired water heater, the electric load would be limited to a control circuit. It would not be included in the load calculation, being insignficant in value, and being (most likely) powered from a general purpose receptacle. An electric water heater with a storage tank would be counted, in the load calculation, at 125% of the rated current. A point-of-demand water heater, without a storage tank, would be counted at 100% of the rated current. Take a look at the two sections I cited earlier.