4 wire thermostat to 3 wire!

[sakm]

Hi all I need to replace my room stat on our central heating

our current one is a 4 wire stat and the new one is going to be a 3 wire stat

the old one (towerstat) has a live earth and by the looks of it two neutral wires

Am I right in thinking the two neutral wires just need to be connected to the same point on the new stat (honeywell T6360B)

Here is an awesome wiring diagram of our set up if it helps at all

Don't you just love microsoft paint!!

 

[jackthom]

Can you post a photo of the towerstat wiring?

 

[sakm]

here ya go

 

[jackthom]

Thanks.
The Red Live Wire in 1 goes into the Honeywell 1
Yellow Switched Live in 2 goes into the Honeywell 3
The Green/Yellow Earth in 3 can be connected to the earth tag in the Honeywell.
Blue Neutral in 4 goes into the Honeywell 2

 

[Wildcat1961]

Hi all I need to replace my room stat on our central heating

our current one is a 4 wire stat and the new one is going to be a 3 wire stat

the old one (towerstat) has a live earth and by the looks of it two neutral wires

Am I right in thinking the two neutral wires just need to be connected to the same point on the new stat (honeywell T6360B)

The only sound advise being to have these works carried out by someone who knows what they are doing (term 2 is not a neutral).

 

[bernardgreen]

Do not switch the Live to the Neutral but instead to the Switched Live

 

[sakm]

Do not switch the Live to the Neutral but instead to the Switched Live

View attachment 132864

That wiring diagram is how its wired now

The LN and E terminals are what's just taken off the wiring diagram on the old stat but the terminals are just numbered inside

After posting I soon realised one was a switched live

 

[sakm]

Thanks.
The Red Live Wire in 1 goes into the Honeywell 1
Yellow Switched Live in 2 goes into the Honeywell 3
The Green/Yellow Earth in 3 can be connected to the earth tag in the Honeywell.
Blue Neutral in 4 goes into the Honeywell 2

Thanks for that jackthom

Upon connecting it all up the call lamp is permanently on!

Edit: its the hot water call that is causing it to illuminate

 

[jackthom]

Thanks for that jackthom

Upon connecting it all up the call lamp is permanently on!

Edit: its the hot water call that is causing it to illuminate

Is it just the lamp misbehaving or is the boiler also running permanently and ignoring the thermostat setting?

 

[sakm]

Is it just the lamp misbehaving or is the boiler also running permanently and ignoring the thermostat setting?

Its ignoring the thermostat but looks to be heating the hot water at the moment

Turning the hot water off turns the light out and it stops heating the hot water

Turning the stat to call for heat does nothing! No light on stat either

 

[oilboffin]

Error in wiring

 

[jackthom]

Can you post a picture of the new thermostat wiring just to make sure? Plus confirm that no other connections in the system have been changed.

 

[sakm]

Sure thing here ya go

Just to point out I missed a S/L in my first wiring diagram on the first post this runs from terminal 10 to the boiler if that helps at all

Thanks for all the helps so far

 

[jackthom]

Looks good.
With the power off... move the yellow wire in 3 over to join the red one in Honeywell terminal 1.
Power up and check that the heating comes on permanently.

 

[sakm]

I will give that a bash

Or I could just pull it all out and wire it to this what's in the manual for the boiler!