Honeywell 42005748 001 Wiring Centre, 24 V

Product Information

Due to several seconds being required for the valve to move from B to A, there is a delay between selecting heating at the programmer and the boiler starting. Possible problems

This is simply the above two diagrams combined. Unlike the Y-plan system, operation of heating and hot water is totally separate, they do not interact or require the presence of the other. Possible problems The motor will move the valve to the mid position AB, so both heating and hot water are selected. Internal switches and other components ensure the motor is held at this mid point. Power on White and Grey

Operation - Hot water only

After removing and labeling all wires, unscrew the old thermostat wall plate and mount the new thermostat’s wall We are currently using Royal Mail Parcelforce and DPD as our delivery providers, all small items will be delivered by Royal Mail, these can take up to three working days to reach you. Older systems simply have the boiler and pump connected to SL (8 in the wiring centre), with only N and E permanently connected. first the history: I have a very old system that hasn't been updated for probably 30 years or so. I have swapped out all the old (rusted/leaking/broken beyond recognition) plumbing connections and in doing so also replaced all the components for modern units (apart from the pump which seems ok) I have not moved anything the positions are all as before. This video covers the wiring and electrical operation of an S plan system with two 2-port valves. Wiring diagrams and further information continues below. View on Youtube. System Wiring

The room thermostat is shown with a neutral connection. However a 2 wire thermostat can also be used which does not require a neutral. I have managed to install the reciever and get the relay working OK, and when you adjust the temperature the relay opens/closes and you see the wireless display call for heat with the flame symbol. The boiler and pump are switched via the valve. Therefore problems with the valve will mean the boiler never switches on, or in some cases will run continuously. This diagram shows the wiring layout using the most typical components. Here, coloured wires indicate the permanent mains supply to the boiler and programmer. The three additional coloured valve wires are also shown (white, grey and orange).Once the valve is fully open, a switch inside connects the grey and orange wires together. Since grey is permanently connected to power, the orange wire provides power to terminal 10 in the wiring centre, and from there to the boiler and pump. Operation - Heating so far i have connected everything apart from the cylinder stat, I was going to use the old switchmaster one that was there but this has different wires and i cannot find any info on it to determine which is which so i will buy a new one tomorrow and fit this in the wiring center shortly

Your new thermostat may not be directly compatible if you see terminals labeled A B C, or 1 2 3, as your system requires a communicating thermostat. When the valve is powered and reaches the fully open position, the grey and orange wires are connected together. This is normally used to activate the boiler and pump. Overview VideoNote that although the orange valve wire is connected to power, this does nothing, as orange is only connected via an internal switch when the valve is in position A. Operation - Hot water and central heating