Noisy HVAC System? Using just a couple of RDL modules, the level of your audio system can automatically adjust to compensate for the increased noise level when the HVAC system turns on. This is useful for background music systems, paging systems or any type of public address or mass notification system.
A contact closure provided either by a dry relay contact in the HVAC controller or an Air Flow Switch installed in the duct work can be used as a trigger to automatically make this adjustment.
The setup is fairly simple:
1.) With the contact closed, adjust the GAIN on the ST-VCA3 for the level required when the air handlers are on.