? re pressure vessel on cold water booster pump

[Branz]

Replaced a Wilo MP 303 EM 3 bar pressure pump just now with a Walrus TQ 800 3 bar pump.
The Walrus comes with an integrated pressure vessel preset at 21 psi
The Wilo, from 2000, did not so there is a pressure vessel on the existing system which set at 31 psi.

Is this going to cause a problem?
Taking it out will require draining most of the HW cylinder which I don't want to waste if it can be avoided.
(Perhaps I can just drop the pressure in that pressure vessel in it to less than the the pressure on the integrated pressure vessel on the pump?)

The existing pressure vessel is plumbed so that it keeps the HW tank pressurised at 3 bar so I wonder will the integrated on on the Walrus do the same thing.
Thanks

 

[Branz]

The answer to the question is that the second, i.e. existing pressure vessel does cause a problem with certain settings on mixer taps as follows:

As mentioned above the HW tank is pressurised, whereas the cold water pressure is provided once the pump starts, the water will flow under gravity if the configuration allows it.
The effect of the second pressure vessel is that the hot water will flow on its own for longer, with the result that not sufficient cold is being delivered to the mixer tap if the cold is not opened sufficiently.