tech_support June 30, 2016 The Caleffi hygroscopic vents don't seal completely, even when tightened. As long as they are dry, they'll allow air to escape. Maybe the ones you had years ago were different? Reply
The Caleffi hygroscopic vents don't seal completely, even when tightened. As long as they are dry, they'll allow air to escape. Maybe the ones you had years ago were different?