Repeated Air in Central Heating System - Help appreciated

[John.g]

I'm in a bungalow so have them both at the highest possible point, but I think it's a moot point as there was contamination every time somebody ran a bath or shower. With all that air and no inhibitor I must have had some serious rad corrosion going on.

I fitted an Adey Magnaclean filter before the boiler at the coolest point and it's pulled out an incredible amount of crud. The back boiler no longer pops and bangs, I'd attributed that to limescale. Must get rid of the latter, will start a separate thread.

I placed the air separator/vent pipe just before the pump suction, the pump is fitted horizontally tilted about 30 deg. System is more or less self bleeding since.

A lot of problem systems have the pump pumping downwards which doesn't help, also helps a lot if the pump head can be limited to 3M or less. My OV system with a combined cold feed and vent does have the pump pumping downwards but its installed downstairs and outside on the boiler return. I run the pump on a PP setting of ~ 4.3M which results in a effective head of ~ 3M and less as the TRVs throttle in.