VRC430, VR61 & VR81 - 2 Zones, both Modulating?

[GeorgeWBush]

Thank you both, you've helped me to decide.

 

[Norcon]

Hydraulic layout 4 will do what you want...

http://www.vaillant.co.uk/stepone2/data/downloads/4c/43/00/vr-61-installation-guide.pdf

S plan-plus in other words.
Compensated flow to both circuits or separately without the use of mixer valves but you still incorporate the vr61.

 

[ALEC1]

so what happens when one zone calls for higher flow temperatures than the other...

I think you will find the 430 will determine the highest flow temp...as the vr 81 will think it is on a mixer, and running in a lower heating curve...

 

[ALEC1]

viessmann or vaillant, the only way to compensate two zones with the same type of heat emitters is to use electronic mixing valves...anything else is a compromise...