How do I apply the Electric Water Heater Exception for Dwellings/Additions 500 sqft or less?

This exception in the code allows any dwellings for additions that are 500 or less to use an Electric Instantaneous water heater.  Three things need to be designated:

  1. The area of all New square footage must be 500 sqft or less.
  2. The water heater must be designated as an Electric Tankless (< 2 gals)
  3. At the plant level of the Tree, in the DHW tab, you must specify the Distribution as Point Of Use (POU)

Our example file, Single Family EA+ADU.bld provides an example of this.

Note the POU credit requires the design of the water heating system meets the criteria in 5.6.2.3 of the Single Family Manual, including the following hot water pipe length limitations:

3/8” pipe – 15 ft
1/2” pipe – 10 ft
3/4” pipe – 5 ft


Categories: 4. Single Family Title 24

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