We built our home here in the mountains of Colorado a number of years ago. We (I) installed a Crown boiler using a single zone recirculating system. It has proven very effective over the years but after installing updated copper distribution & return units on the upper level I've been experiencing recurring vapor locks. The boiler is located on the lower floor and the copper distribution and return are located on the upper floor.
Someone suggested that we install an air bleed valve in conjunction with the copper return. Would such a setup work to solve the problem and what are we looking at in cost?
Thanks for any suggestions.

It might be a band aid for the problem but the real answer is to find out WHY the upstairs keeps getting air bound. It's possible you may have to increase the boiler pressure slightly. At what pressure is it currently running?