Air in lines, no purge valves

chagob

I have an older boiler that constantly rattles my pipes. Bleeding the radiators hasn't helped. There are three zones, one for each floor basement, 1st floor, and attic (2nd floor) with mechanical circulating pumps. that look to be on the return side of the circuit. There are several different sizes of pipes leaving the boiler. The expansion tank seems to be at the end of a run of pipes and doesn't have any type of scoop or airvent. One of the Flo Control Valve seems to have some corrosion around the connections.
I would like to do the following whenever the weather is warm enough for me to cut off the boiler for the season:

• Add a ball valve and drain valve near the circulator pumps for each zone. Can I add them about a foot above the pumps?
  
• Maybe relocate the expansion tank, if necessary, and add a scoop and airvent. If this seems logical to help with air in the pipes, where should it be relocated?
  
• Replace Flo Control Valve that has corrosion
  
  
  

HVACNUT

Looks like someone changed the system from air control to air elimination. You can see the old compression tank in the rafters. Only they forgot to install an air eliminator. Duh.

Who could have done that I wonder?

chagob

I bought the house last year and I've seen all types of craziness

pecmsg

Find someone that knows hydronics and re-pipe it.

pecmsg

Just realized you still have galvanized potable water piping!