Central Heating Room Thermostat Wiring Help

[Nicovid]

I need some advice on replacing an old Central Heating thermostat with a new digital Honeywell THR840DUK. The Thermostat controls an Oil fired boiler which provides Hot Water & Central Heating.

The old thermostat I'm replacing is a Potterton PRT100 and is wired as follows.

House Wiring Potterton Thermostat

• Nicovid
• 25 Oct 2010
• 1

The wires are Red, Yellow & Blue. (The white colouring is actually paint)

Wiring Diagram for Potterton PRT100

Potterton PRT100 wiring diagram

• Nicovid
• 25 Oct 2010
• 1

Please can some one advise what wires I need to connect to the new thermostat A B C

Honeywell THR840DUK Wiring Diagram

• Nicovid
• 25 Oct 2010
• 1

Many thanks.

 

[stem]

Old stat

Blue, Terminal 4 = Neutral
Yellow, Terminal 2 = Heat
Red, Terminal 1 = Live

New Stat
Yellow = B
Red = A

As the "Neutral" is not required then isolate the blue wire but do not connect it to A, B or C

 

[Nicovid]

Thank you very much. That has worked a treat....Excellent.

 

[Taylortwocities]

Why do people never look in the WIKI?
//www.diynot.com/wiki/electrics:how_to_replace_a_room_stat