The DHW expansion vessel seems to be full of water when the car tyre type valve on the top of it is depressd. As I have other work to do on the boiler I decided to change this vessel as well, as it is not too expensive.
The manual with the boiler explains how to change the vessel but there is no mention of what pressure it should be set to. (My DHW system just outputs from the boiler to the hot taps).
What should the pressure be set to and what is the procedure for pressurising the vessel?
The new vessel will come with the correct pressure in it.
You can use a tyre pressure gauge to test the pressure if you wish but make sure the system water pressure is nil before testing.
Use a foot pump to top up if required.
The DHW vessel is the size of a teacup. It came out of a sealed Vaillant package and has no pressure in it. I can easily pressurise it but to what pressure? or does it not need to be pressurised and that is why there is no reference in the manual to pressurising it?
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