Code Cycle: 2016 & 2019 Standards
Reference: CalCERTS Alterations Training Manual Chapter 9, Section 7
Applicable to Existing Duct Systems Only!
During RCV (Refrigerant Charge Verification), if an existing duct system cannot achieve the minimum 300 cfm/ton airflow requirement, then the Installer must perform RA188.8.131.52.5.1 (airflow) Remedial Actions and the HERS Rater must verify that the Installer attempted each of the applicable steps. However, if at any time during the airflow remediation steps the system achieves =300 cfm/ton, then the remedial actions may be discontinued and the RCV may proceed using the measured airflow. Otherwise, after attempting all of the applicable steps, the system will be considered in compliance and the refrigerant charge verification shall proceed using the best airflow rate attained.
Note: if the airflow remediation steps are used to demonstrate compliance with the minimum airflow requirements (measured airflow is never =300 cfm/ton), then an OCST (Occupant Controlled Smart Thermostat) must be installed as per JA5, and is verified by the Building Official (not the HERS Rater). Achieving =300 cfm/ton during the remediation steps would eliminate the requirement for installation of an OCST.
RA184.108.40.206.5.1 - Remedial Actions
The installer shall attempt to correct non-compliant system airflow by performing the following remedial actions:
- Check to determine that the air filter media is clean. If the air filter media is dirty, then replace it with clean filter media.
- Open all registers and dampers and remove any obstructions.
- Replace crushed, blocked or restricted ducts if possible.
- Check to determine that the evaporator coil is clean, or that there are no obstructions to airflow through the evaporator coil. If the evaporator coil is dirty or blocked with debris, if possible, clean the evaporator coil using a method approved by the manufacturer.
- Set the air handler fan to high speed for cooling, and ensure that the blower wheel and motor are operating properly, within manufacturer's specifications.
- Check to determine whether the return duct system or return filter grille is sized too small for the installed system. If the return duct or return grille is sized too small, if possible, perform applicable alterations work on the return duct system or return grille in order to improve the system airflow rate.
When performing these remedial actions determines that there is a fault, a corrective action shall be performed if possible. In many cases, airflow can be improved by adding a return duct and filter grille, or enlarging the existing return duct or filter grille. Alteration of the return duct system is an alternative that shall be considered if applicable to the existing system, and if other remedial actions do not improve the airflow. Alteration of the return duct system to bring the system airflow rate into compliance is expected to be attainable for systems with ducts in an attic space with sufficient clearances for accommodating improvements to the return duct system.