air elimination

Hi all, I bought this house recently and am still learning the systems. I have a 2 zone, oil-fueled hydronic heat system, and the circulator pump just broke (or rather, is breaking). I have a new one and am ready to install it. My plan was to drain the system from the drain valve (bottom circle...

There are two issues I observe in my boiler heating system: (a) excessive pressure variation and (b) air trapped in the system. The distance from the lowest to highest point in the system is 8 feet, thus the minimum required pressure would be (8 / 2.31 + 3) ~= 6.5 psi. The operating pressure...