It occurred to me to wonder to what extent the recommended cold charge pressure for a sealed system depends on the position of the pressure vessel and gauge.
I have seen lots of suggestions saying that the easiest way to convert an existing vented system is to replace the F&E tank in the attic with a pressure vessel in the same position.
However, many systems (particularly if using a system boiler) with have the pressure vessel and gauge quite close to floor level on the ground floor. In an average house, this represents a difference of about half a bar of static pressure between these two positions. If the gauge is in the attic, do you pressurise to half a bar less than if it were at ground level?
Roger