Thanks D_Hailsham,
Speaking with Viessmann technical, they did not recommend relying on the internal bypass as a sole means for arranging pump overrun.
I'd be interested to hear feedback from installers as to whether the integral bypass valve has proved in practice to be an acceptable...
Is it possible to combine a Y plan 3 port valve and an S plan two port valve onto the same boiler system?
This enquiry is made to see if it is possible to achieve 1 x HW zone and 2 x Heating zones within the same system, but without the ineherent bypass problems of achieving pump overrun in...