We went for a Viessmann in the summer, we previously had terrible hot water flow, but went for a pressurised hot water system w/Viessmann tank. H/W Tank is now in the garage, and no water in the loft, so we can insulate the loft without worry of burst pipes. Hot water flow is now mega. The heating is now really quiet, can’t hear it come on. We had a 26kw boiler for a 5 bed detached house, which I thought was underspec’d, but I checked the calc’s and it’s actually slightly over (overspecing is not a good thing as it’s less efficient),
Really pleased…although it’s not got cold outside yet. I don’t much like the Viessmann controller, quite complicated, and doesn’t do everything i’d like it to, but other than that, it’s been great.