Thinking about fitting a Vitodens 100 system boiler in a refurb farmhouse. The Viessmann system boilers are 4 pipe, I believe, so flow and return to rads/underfloor heating manifold and flow and return to unvented (Tribune) cylinder, with the 2 port valve on the cylinder wired only to the high limit stat? I'm guessing the boiler has a 3 port in it and works as a Y-Plan, or am I completely off the mark? Also, any recommendations on the best controller to use?
