Revenheat RSF820 Boiler Problem?

Hi

I recently moved into my new house. There is a Revenheat RSF820 boiler installed in the house. The Problem is when I open a hot water tap, the hot water also goes to the readiators even when the heating is off and all radiators in the house warm up. I have tried to switch tap/heating nob to tap water only but no difference.

This is really bugging me becasue whenever I open a tap, there is no hot water as all the hot water goes to radiators first.

I would really appreciate any help/advice on this.

Many Thanks.

M M Gulzar
February 2010