Further to discussions a few months ago in the group I've followed the recommendations of the experts and bought the following components to upgrade my simple CH/HW setup to a fully controlled Honeywell Y plan system :
- Honeywell wiring centre (not a terminal block) - V4073 22mm mid-position valve - L6400C full programmer - L641 tank stat - CM67RF wireless room stat
These will be connected to my existing Baxi Solo 3PF pump overrun boiler and my current pump. The plan is to install all the electrical bits in the airing cupboard relatively close to the cylinder so that I don't have to extend the wires.
In advance of actually installing everything, I am installing the components screwed into a piece of wooden board with the pump/boiler simulated by a standard 240V lightbulb, so that I can make sure my understanding of how the components all work together matches reality. The questions are :
- does anyone know how to wire a CM67 to a Honeywell wiring centre ? I don't have a schematic for it. The room stat terminals on the wiring centre are marked E, 1, 2 and 3. The terminals on the room stat itself are N & L plus A, B and C. I could buzz it out with my meter but I'd feel more confident hearing from someone who'd already done it :)
- do I need a bypass valve ? My bathroom radiator has no TRVs fitted, so I assumed there would always be a route between the flow and return irrespective of the position of the three-port valve.