Repressurising expansion chamber Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[steveglos]

I need to repressurise the expansion chamber on my sealed system as it has lost pressure though a faulty valve. Do I need to drain the system or can I pressurise it whilst it is still full? Thanks.

[Oliver_murphy]

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.

Hope this helps.

[steveglos]

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.

[Oliver_murphy]

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,