I have a fully pumped CH system with 2 motorised valves, one for CH and one for HW. I preparation for getting a new HW cylinder fitted I was sorting out and rerunning the cables in the airing cupboard to tidy them up. I made a note, or thought I had, of the connections in the junction box. The HW now isn't working. I have opened the valve manually to get some HW. CH is ok.
Can somebody point me to a wiring diagram for a 2 valve pumped CH system.
Thanks
Kevin
or
Yes, I see that Adam has done so. The arrangement which you have is called an 'S' Plan. It needs to be wired so that the HW demand from the programmer, in series with the Cylinder Stat, provides power to the HW zone valve. Similarly, the CH demand and Room Stat need to drive the CH zone valve.
Each of the zone valves has a set of auxiliary contacts which close when the valve is open. These need to be wired in parallel with each other, with a permanent live to one contact of each, and both outputs connected to the boiler/pump demand. That way, the boiler and pump will run whenever either or both zones have an unsatisfied demand.
[This should be apparent from the S-Plan wiring diagram, but I thought that a verbal explanation may also help].
Probably an S plan as in the diagram Adam posted.
Make sure there is a live via the cylinder stat to one side of the DHW valve motor, and the other side of the motor is connected to neutral. The valve must open if these conditions are satisfied.
I spent this morning on Google studying diagrams and not only did I not make the correct notation before disconnection but I am not convinced the wiring was right before although everything did work before. One more question, how can I tell if a wire is neutral? I mean just because it is black doesn't make it neutral. I need to verify it is neutral. I know it is meant to be 0 volts so if I measure between the suspect wire and earth and I get 0 volts can I assume that it is neutral. I have determined the permanent live wire. I need to verify which is the switched live and neutral.
Kevin
Probably an S plan as in the diagram Adam posted.
Make sure there is a live via the cylinder stat to one side of the DHW valve motor, and the other side of the motor is connected to neutral. The valve must open if these conditions are satisfied.
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