UFH - 4 core old and 2 core new Actuators

[Gsysaxman]

Replacing 15 year old FAR Italian manifolds (2 downstairs, 1 up) with new Warmup units. However, old actuators have 4 core and new only have 2 core. Can someone please explain what the additional 2 cores are used for in the old actuators and how to modify the wiring for the new, and perhaps if at all possible supply a wiring diagram for an S Plan system with 4 zone valves - 1 for manifolds downstairs, 1 for manifold upstairs, 1 for two towel rails upstairs, 1 for hot water. Many thanks for any help.

 

[brianmoooore]

4 wire actuators incorporate a switch that operates when the actuator is 'on'. This switch will be connected in parallel with the ones on the other actuators, and used to turn the boiler and pump on.
A 2 wire actuator system will have a diode connected to the 'live' wire of each actuator, the second wire from each of the diodes are all connected together and connected to a relay. The contacts of this relay are then used to switch on the pump and boiler.

 

[Gsysaxman]

4 wire actuators incorporate a switch that operates when the actuator is 'on'. This switch will be connected in parallel with the ones on the other actuators, and used to turn the boiler and pump on.
A 2 wire actuator system will have a diode connected to the 'live' wire of each actuator, the second wire from each of the diodes are all connected together and connected to a relay. The contacts of this relay are then used to switch on the pump and boiler.

Thank you, thats very helpful.

 

[brianmoooore]

You get similar with 2 port zone valves. Some have just a blue and brown wire (plus sometimes an earth) which operates the valve motor. Some also have grey and orange wires, which connect to a microswitch which operates when the valve is open.