Switchmaster to Hoenywell wiring

[TrickyP]

I have replaced my 3 port valve with a Honeywell 3 port mid postion and have the situation of orignal 6 wire connection to 5 wire and not working properly.
I have connected the wiring as per a post i found but the central heating when activated turns the boiler on and the pump so that works fine but when i activate the heating side the valve moves but does not tell the boiler to come on. I have a spare black wire that when C/H is on there is zero voltage and when the H/W is activated the voltage is 240vac but having no wire connected i think this is my problem. Does anyone know how this wire is used to turn the boiler on or where i have gone worng please?

Thanks in advance for your help.

Richard

 

[D_Hailsham]

Do you mean a Black wire from the valve? The usual colours for a Honeywell V4073 are blue, white, grey, orange and green/yellow.

What are your colours?

Here is a wiring diagram for a Y plan:

 

[TrickyP]

The black wire is in the junction box where all the wires terminate to. The black wire comes from the thermostat on the immersion tank (i think from memory). When the heating comes on i get 240vac to it. I have been told to link the terminals that had the red and orange together but if i do this the c/h pump comes on when the h/w comes on which is not correct. Hope thats a little clearer.

 

[D_Hailsham]

The black wire is in the junction box where all the wires terminate to. The black wire comes from the thermostat on the immersion tank (i think from memory). When the heating comes on i get 240vac to it. I have been told to link the terminals that had the red and orange together but if i do this the c/h pump comes on when the h/w comes on which is not correct. Hope thats a little clearer.

Here is a diagram showing how the Y plan pipes are connected

Does your look anything like this?

There should be three cores in the cable from the HW cylinder thermostat to the junction box and there need to be a connection from the HW ON and HW OFF terminals of the time switch to the junction box as per the wiring diagram, apart from the HTG connection.

If you don't have this, you will not get heating when the hot water is turned off by the cylinder thermostat or at the time switch.

For info, the wire colours of the Honeywell compared to the Switchmaster are as follows:

Switch Master: Green/Yellow = Honeywell: Green/Yellow
Switch Master: Blue = Honeywell: Blue
Switch Master: Yellow = Honeywell: White
Switch Master: White = Honeywell: Grey
Switch Master: Orange = Honeywell: Orange
Switch Master: Red = Honeywell: NO wire. link old Red and Orange terminals together