Thermal Vacuum Valve (TVV)

Cool sensing portion of TVV to less than 95°F (35°C) by immersing in cool water. Blow air into one of the pipes. Ensure that TVV is closed. Heat the sensing portion of TVV to 129°F (54°C) by immersing in hot water. Blow air into one of the pipes. Ensure TVV is open. If a problem is found, replace TVV.