The expansion vessel can be charged with a full system, although I dont recommend it.
Drain the system, and hold open the PRV. When its all open, a standard Schrader valve (I thinks thats spelt right, if not, a standard Bike Pump Valve) pump it up to around 1 bar of pressure. You should dip the needle on the valve first though, see if any water comes out. If you get water, you have a split diaphram, and the entire vessel needs changing.
Thanks Oliver, would letting the pressure out of the system be good enough? I don't want to drain it if I don't have to as it takes ages to get all the air out and I'll have to get more additive! Thanks.
If you leave the system with water in it, when you try to re-pressurise the vessel, you will be trying to force 1-3 bar of water out of the vessel. It is better to drain it down, leave an open point (the PRV) and the re-pressurise. THis will force all the water out of the vessel easily, and put less stress on your pump, and wrist!!!!
If I do this for a customer, this is exactly the procedure I follow. Tried and tested,
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