Swapping mechanical to digital thermostat

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Morning all, and merry Christmas.
I am looking to replace my old sangamo choice rstat1 with a moes but-002 go. A bit of back ground. Downstairs we have water underfloor heating upstairs there are radiators. I have 4 room stats downstairs and leave the boiler on all. The time and control the temp via room stats and this works well. The problem is that the upstairs has only a mechanical thermostatic switch that we now need to manually adjust when we want the radiators to come on. I wanted to switch to a moes but 002 to be able to set a timer for this. I am a bit lost on the wiring. The sangamo has a live and live switch connected with the neural not connected. The bht 002 needs all 4. I have connected the live at the boiler and can get bht operational but cannot get the heating to operate. I have 240 v on live and neural, and live switch but i cannot get heating on. Any ideas ?
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I have connected the live at the boiler
your thermostat does not connect to the boiler in any way, it gets wired to the zone valve controlling that zone , the valve tells the boiler when to come on
 
Ian thanks, you are correct it does not need connected to the boiler. I grouped it in with other neutrals to get power to moes thermo, otherwise it does not power up. I can hear the moes switch “click” when adjusting temp but the valve at boiler does not move.
 
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Ian, please see below, colours are as per picture above. The Boiler end i have but notes as to where the cables are.
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For 230V motorised valve control, the new stat replaces the Honeywell as follows:

Brown wire (Live) in Honeywell 1, goes to new stat L 4

Grey (Switched live) wire in Honeywell 3, goes to new stat 2

Insert a link between new stat 4 and 1 so that the two terminals are joined together.

The black wire needs to become a neutral connection. So assuming that these are both ends of the same wire....

2.jpeg


....then the thermostat end connects to the new stat N 3, and the other end to an existing neutral connection. Ideally a blue sleeve should be slid over each end to show that it is being used as a neutral connection.
 

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