water coming out of shower when taps are off

[nvg]

I have recently moved into a newly built apartment (Nov 07). It has a pumped shower system with a combination tank.
The problem is that water comes out of the shower in short bursts of about a minute at a time when the taps of the shower taps are turned fully off. This happens about twice a day. TIt does not seem to be related to the heating coming on as it is happening around 3-4am most mornings. This has been happening since I moved in.
I keep the switch for the pump on 24 hours.
I have been told by the builder that this is normal and is due to the pressurized system making the water come out even when the taps are closed.
The pump is a monsoon negative 2 bar twin pump.
Would anyone have any ideas on what can be done to prevent this as it is waking me up in the middle of the night!

 

[clf-gas]

Speak to your neighbours, if they built more than one house the likelyhood is the systems will be the same, therfore all of them will be releasing pressure. Failing that your builder is feeding you a line and avoiding snagging faults, a tale of things to come