I have a 12kW electric water cylinder and a 12kW direct gas fired water heater. Can anyone please explain what I need to check to ensure the performance requirements comply with ASHRAE 90.1 2007 table 7.8. I dont understand the rating condition and performance required headings.
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
January 6, 2016 - 10:19 am
The Subcategory or Rating Condition refers to the type of water heater and/or its storage capacity.
The Performance Required is a formula used to determine the minimum efficiency of the equipment. So for a 12 kW electric, tank-type water heater the formula you use is 0.93–0.00132V EF. The note below the table identifies the variables V and EF. A clearer way to see this formula would be EF = 0.93–0.00132V. So put the volume of the tank in the equation and calculate the EF.
Ciaran McCabe
DirectorPassive Dynamics Sustainability Consultants
12 thumbs up
January 6, 2016 - 10:44 am
Great thanks.