Hvac School - For Techs, By Techs

In this short podcast episode, Roman Baugh takes over the HVAC School podcast to answer a listener-submitted question about VRF (or VRV) system evacuation. Evacuation is a critical step of making repairs on VRF systems, which are very diverse and versatile but require a high level of understanding. VRF systems have multiple indoor units per outdoor unit, and they achieve that with the help of several components and accessories down the refrigerant line that can pose issues in evacuation and pressure testing. In heat recovery units, some manufacturers use solenoid valves (or even electronic expansion valves) in branch selector boxes or branch collector boxes. These valves act as little traffic guards, and the system needs to be put in its refrigerant recovery or vacuuming mode. If not, then you won't be able to evacuate all of the refrigerant and non-condensables from the system. Even if the system passes a decay test, contamination is a major concern when the system starts up and the valves open (due to nitro