Hi
I want to replace a Switchmaster 805 with a Horstmann CentaurPlus C27 series II but am confused about the current wiring arrangement. As you can see from the photo, there's a five-core flex to the back-plate but what's confusing me is (a) the green/yellow wire in position 3 and (b) no wire in the earth connector. I presume the gn/yllw isn't an earth - looking in the separate wiring centre box, a gn/yllw (with black tape round it) and brown wire are joined together at position 8 (HW OFF) so I'm surmising that the gn/yllw at 3 in the back-plate is the same but just hasn't been sleeved in the same way. So, a few questions if you don't mind:
1) is what I suspect correct and, if so, is it normal practice or do I need to worry?
2)the wiring diagram for the C27 suggests a requirement for an earth in the appropriate back-plate terminal but I'd then only have two wires left for positions 1 - 4 when I need three. If my suspicion above is correct, though, and the disputed wire isn't currently an earth, then there wouldn't be a problem (presuming no earth is needed in the new one either).
3) Given all this, could someone please confirm that the new wiring positions would be as follows:
[Existing N -blue L -brown 1-red 2-empty 3-gn/yllw 4-black (no earth)]
New - N-blue L-brown 1-black 2-empty 3-gn/yllw 4-red [no earth]
4) Finally, do I need to remove the circuit link in the back of the C27 programmer unit? Sorry but I don't know what kind of CH system I have - all I can say is the boiler is a Baxi Solo 2 50 PF and there's a Grundfoss 15-60 pump and an ACL Lifestyle MPV before the HW tank. At the moment, CH and HW are timed together but you can turn either on/off separately via the CH constant/HW constant buttons on the 805.
Thanks a lot
I want to replace a Switchmaster 805 with a Horstmann CentaurPlus C27 series II but am confused about the current wiring arrangement. As you can see from the photo, there's a five-core flex to the back-plate but what's confusing me is (a) the green/yellow wire in position 3 and (b) no wire in the earth connector. I presume the gn/yllw isn't an earth - looking in the separate wiring centre box, a gn/yllw (with black tape round it) and brown wire are joined together at position 8 (HW OFF) so I'm surmising that the gn/yllw at 3 in the back-plate is the same but just hasn't been sleeved in the same way. So, a few questions if you don't mind:
1) is what I suspect correct and, if so, is it normal practice or do I need to worry?
2)the wiring diagram for the C27 suggests a requirement for an earth in the appropriate back-plate terminal but I'd then only have two wires left for positions 1 - 4 when I need three. If my suspicion above is correct, though, and the disputed wire isn't currently an earth, then there wouldn't be a problem (presuming no earth is needed in the new one either).
3) Given all this, could someone please confirm that the new wiring positions would be as follows:
[Existing N -blue L -brown 1-red 2-empty 3-gn/yllw 4-black (no earth)]
New - N-blue L-brown 1-black 2-empty 3-gn/yllw 4-red [no earth]
4) Finally, do I need to remove the circuit link in the back of the C27 programmer unit? Sorry but I don't know what kind of CH system I have - all I can say is the boiler is a Baxi Solo 2 50 PF and there's a Grundfoss 15-60 pump and an ACL Lifestyle MPV before the HW tank. At the moment, CH and HW are timed together but you can turn either on/off separately via the CH constant/HW constant buttons on the 805.
Thanks a lot
