On Thu, 27 Jan 2005 19:28:21 +0000, Rick wrote:

Every time the CH is started up after a few hours off, it gurgles like
mad from the pump and three radiators quickly fill with air - two of
them over half full of air (from feeling where they are warm/cold). It
takes a good couple of minutes to bleed them.

Sounds like the pump speed is too high. You are probably sucking air
in down the vent when the pump is switched on. Try turning the pump
speed down.

M.