Posted by Harold Kestenholz - Hydronic Network on December 27, 2000 at 17:45:42:
In Reply to: Air Vents & Vacuum posted by pat on December 27, 2000 at 16:33:27:
Vacuum vents have not been available for some years so the vents you have do not have the capability of permitting a vacuum. If you succeed in creating a vacuum, you also need the little trap box that was near and above the boiler that broke the vacuum at a negative pressure to prevent collapsing part of the system from excessive vacuum - if that part is still in the system, then the electrical valve idea is safe. You could use a vacuum sensor control to open an electric valve at a particular negative pressure setting also.