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A220.127.116.11.5 Exhaust Air Heat Recovery
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Heat recovery requirements based on ASHRAE 90.1, Section 18.104.22.168 are adapted and modified for California climate zones as described below.
- Systems with minimum design outdoor air fraction of 80 percent or greater and supply air flow of 200 cfm or greater in climate zones 2, 9, 10, 11, 12, 13, 14, 15 shall have a heat recovery system.
- Heat recovery systems required by this section shall result in a net sensible energy recovery ratio of at least 60 percent for both heating and cooling as tested using AHRI 1060-2014 or 1061-2014 and certified by AHRI. A 60 percent sensible energy recovery ratio shall mean a change in the dry-bulb of the outdoor air supply equal to 60 percent of the difference between the outdoor air and exhaust air dry-bulb at design conditions. Provisions shall be made to bypass or control the energy recovery system to permit air economizer operation as required by Title 24, Part 6, Section 140.4(e), Economizers.
- Systems serving spaces that are not cooled and that are heated to less than 60°F.
- Where more than 60 percent of the outdoor air heating energy is provided from site-recovered energy.
- Where the sum of the airflow rates exhausted
and relieved within 20 feet of each other is less than 75 percent of the design outdoor air-
flow rate, excluding exhaust air that is:
- Used for another energy recovery system;
- Not allowed by ASHRAE Standard 170 for use in energy recovery systems with leakage potential; or
- Of Class 4 as defined in ASHRAE Standard 62.1.
- Systems expected to operate less than 20 hours per week.