Replacing 4 wire thermostat with 2 wire thermostat

[Wright39]

Hi guys,

Im replacing my old honeywell thermostat with a siemens more modern looking one. The old one is wired to a 4 wire system but the new one apparently only uses 2 wires..... Please can you help. I have attached photos

Untitled

• Wright39
• 3 Feb 2013
• 1

The terminals are 2341 from top to bottom of image

Untitled

• Wright39
• 3 Feb 2013
• 1

Here are the wires: blue 2, yellow 3 and red 1

Untitled

• Wright39
• 3 Feb 2013
• 1

Here is the wiring diagram

Untitled

• Wright39
• 3 Feb 2013
• 1

And here is the new thermostat.

Dan

 

[Whitespirit66]

Red to L
Yellow to Y1

Make safe bare ends of blue and earth and tuck out of the way, as not needed.

 

[Dan Robinson]

Or Red to Y1, Yellow to L

 

[Whitespirit66]

So, which way is best?

Untitled

• Whitespirit66
• 30 Nov 2010
• 4

 

[Dan Robinson]

 

[Wright39]

I'm a lover not a fighter. And would love an answer?

 

[Dan Robinson]

You've had two answers, and either would do, although W's is more conventional.

 

[Wright39]

Ok thanks guys.