how do you repressurise an expansion vessel for a water system?

hello is any1 to help, my problem started when i turned on the c,heating pressure would rise to the red area, so i had to bleed some water out of radiator to make it stable,(no water was releasing from pipe going out side ).when i turned c,heating off the pressure would fall to zero, so i had to fill some water into system,found the problem it was the pin inside the valve on the expansion vessel( not much pressure in vessel ), borrowed my friends tyre valve pin remover and changed the pin inside,pumped 1.5 bar air pressure into the vessel(is that the right pressure vaillant ecotech pro28 r1)
now pressure alright but after a few hours later the radiators seem to be a bit cold,have i done this wrong pressurising the vessel. appreciate any help,thanks rookie

rookie
January 2010

so all the water has to drained out of rads

rookie
January 2010

First check to see if you have any water coming out of the tyre valve on the vessel-if you have fit new exp vessel.

To repressurize an expansion vessel you will need to depressurize the system to 0 bar and allow any water that is displaced (when pressurizing exp vessel) to vent out through the drain cock that you used to depressurize the system.

Using a tyre pump on the tyre valve on the expansion vessel set the correct pressure usually between 0.5-1 bar (check boiler specs).

Refill system bleed any air in rads approx 1-1.5 bar.

daz71
November 2008

>do you need to turn off the water pump and open the tap.

the boiler should be off so the pump will not be running
as for the tap you are working on the primary side not the dhw.

isolate the boiler, make sure you have no pressure in system, so gauge on the front of boiler will be on 0.
then you can repressurise the vessel.

hi-spec plumbing
July 2007