In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
I'm experiencing the same percolating issue with my Buderus G124X as described in http://www.heatinghelp.com/forum-thread/98918/Percolating-Buderus-Boiler and am going to replace the expansion tank to see if that addresses the issue. I came to this decision after allowing the boiler to cool-down (to ~100) then tapping the tank: it sounds muffled all over, whereas I believe it should "ring" (on the lower half, at least.)
The tank is an Amtrol 30 attached to a Taco air scoop upon which a Caleffi HiVent is installed, and located on a horizontal trunc line above the boiler.
Can I replace the tank without having to drain the system, if I first close every shut-off/isolation valve I can find (including the cold water supply line) and allow the boiler to cool down (to ~100?) I think I should expect some (minor) water discharge -along with an air "pop," assuming the bladder has any air left in it at all- when removing the current tank but, wanted to seek qualified guidance before going any further.
Thanks in advance...