Thermal Vacuum Valve (TVV)

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