Nest Install on Worcester Bosch 35CDi

[steve@home]

hi all any chance of a looky at this for us please


Have a Drayton heating programmer looks an easy change over to the Nest control unit and thermostat (Honywell t40) just want to get my head around it before i start on programmer currently have this config:

n = 2 wires blue
L = 3 wires brown
1 = 1 wire brown Common looped to live
3 = 1 wire black call to heat
earth to base

Programmer is on a plug with a 5amp fuse going into a RCD Socket There is no fused spur going directly to boiler for live, the live is taken from progammer and then this is then looped to a terminal block were it meets the switched thermostat which then activates the boiler call for heat were the wires travel back to boiler

Honeywell t40
Earth
3 = Blue
1 = Brown


I have had a look at the nest install for this as a combi boiler looks like all you have to do is
move the common over to no 2 and link with live and 3 is black call for heat and the other
wires should i wire as is or find which ones go to thermostat and disconnect them
many thanks, also is it good practice for this to be wired this way or do i need to wire boiler separately with its own power source

the nest thermostat will have to wire from usb or see if i can link it to downgrade to 12v existing wires

best all

 

[mcmoby69]

It will work as you suggest.
Although connections will be a bit tight for linking the live over. Hope you tidy those ends up properly.
There's a few loose strands in there.
Leave the existing stat in place but link the wires out so it doesn't operate.
You can sort it out properly when you decorate next year.

 

[steve@home]

Thanks for your Reply looking at the boiler i traced back wires to this from programmer looks like a bit of a doggy install from plumbers cost me around 2700 for this replacement boiler, when i had my loft ext done were they removed my old convectional boiler out of the loft had a cylinder up there and the middle bed room had motorized valves & Pump to control flow on this system, i have 5 core plus earth running from boiler to this bedroom were i believe it meets the room stat wires and then from there it travels back to programmer as photo unfortunately i have the dreaded wooden flooring down in that room and its not going to be easy to disconnect the wiring for the room stat, I can see the 5 core going up and a separate 5 core coming down through my ceiling space going to programmer and have easy access to it what if i just chop that giving me enough room to wire to the programmer/nest link will be bypassing the the upstairs connections the only issue i have is that once its wired like that there will be a direct connection to boiler be it the same way it was last time with the drayton programmer no fused spur is this acceptable
as for the wires will probably solder or crimp together thanks, they do look a bit naughty but that was installed by a corgi registered plumber

best steve

 

[steve@home]

Thanks all for your comments will be putting in after Crimbo


best all