First thing to make clear is am not an electrician or plumber. I would
really appreciate the advice being non-technical.

I have a central heating system with 2 Honeywell V4043H1C56 actuators.

The hot water one (nearest the immersion) is working fine but the
other which controls the hot water going to the rads sticks &
therefore needs to be replaced.

First thing to make clear is that it is old & therefore I am having to
replace the actuator & install the converter plate as it is not the
more recent all in one model. Therefore I do have to drain the system.

Problem & therefore advice I need concerns the wiring. The currently
fitted old model has 5 wires, the new model has 6, the most
noticeable difference being an extra white wire.

Wiring in the cupboard is as follows - Colour at the start of each
line is the one from the current actuator

1. Blue & a 2nd blue feeds into to wiring block with a Blue, Blue &
Black on the other side of the wiring block.

2. Grey & a 2nd grey feeds into a Blue & Brown on the other side

3. Green with yellow stripe & a 2nd Green with yellow stripe feeds
into 2 Green with yellow stripes on the other side

4.Red & a 2nd Red feeds into a Red on the other side

5.Black is joined together with one yellow wire


This leaves two questions for installation of the new actuator-----

Do I use the brown wire on the new actuator in the same way as the
black in the previous & what do I do with the white wire in the new
actuator ?

Many thanks for anyone who can give me help.

Neil