One radiator has needed to be bled twice in the last month on our brand new CH installation. Is this something one should expect or a cause for concern would we think? Is it just the system “settling down” during its first use in anger or something??

TIA as always.

Combi or standard system?

Combi.

i’d suspect its settlement, air is present in water and on filling a new pressuriesed system plenty will be dragged in,
if your venting the rad because its cold at the top its full of air. the air will normally occur at the highest point of the highest rad ( normally the bathroom)

always use this process even if the air is only present in one rad..

turn off the boiler .. let the rads cool to room temp.. start downstairs and work your way around the rooms .. go up stairs and do the same leaving the highest rad till last..

if at any point the air stops hissing as your venting a rad tighten it up and refill the system at the boiler to circa 1.5 bar and statr again at the last rad.. when complete fill system agin to between 1 and 1.5 bar..

caution.. do you know how many rads we replace because people over tighten the air vents?? literally just nip em up nothing more..

job done..

Is it much? Possibly hydrogen if the system hasn’t been flushed.