Changing room Thermostat

[ekblue]

Hi all

Looking for advise on changing my current mechanical thermostat for a digital one. Any recommendations on what's best price wise?

I currently have a Lifestyle model with three wires in the back, plus earth.

Red (live)
Yellow (load)
Blue (N ??)

A few models i've been looking at online only require 2 wires. Can anyone help with the wiring? Does the Blue need made safe?

Thanks in advance.

 

[ekblue]

Anyone?

 

[Hugh Jaleak]

Choice of stat up to you, but Honeywell/Drayton/Siemens probably better than cheaper versions. Depends how much control you want, some can be set for different temps at different times.

Don't assume anything on the wiring without checking, but assuming blue is Neutral then make safe both ends, red is supply, yellow switched live (load).

 

[jackthom]

Because you probably have both Live and Neutral available at least you can have a mains powered unit, which I would personally prefer to batteries.

 

[Galoka]

Do you want a basic on/off stat to replace you existing one, or do you want a programmable one- which allows you to set different temps through the day

 

[malcolmallan]

I just got the CM907 which I think will be great - but doesnt seem to be working on my system... not sure its not a wiring issue though!

 

[D_Hailsham]

I just got the CM907 which I think will be great - but doesnt seem to be working on my system... not sure its not a wiring issue though!

1. Do you have an existing timer?
2. How have you wired the CM907?
3. Do you have a multimeter and know how to use it?

 

[malcolmallan]

1 yes, i have an existing timer... Its a lifestyle lp722.

2. An electrician wired the cm703 for me... He took out the old mechanical one and put i the cm703... Only two wires i believe?

3. No i dont im afraid

I was hoping that the electrician would have been able to do it... The boss of the electrical company came out today with the plumber. The plumber said all the valves are working so must be electrical and reckons it is possibly incompatible wih the lifestyle programmer??

I dont think the electrician is a heating specialist.

 

[D_Hailsham]

The plumber said all the valves are working so must be electrical and reckons it is possibly incompatible wih the lifestyle programmer??

Then the plumber doesn't know what he is talking about.

I dont think the electrician is a heating specialist.

Not unusual.

Here's how you can check it yourself.

Turn OFF the electric supply to the system
Remove the new prog stat from the backplate
The wiring should be as follows:
Red - Terminal A
Yellow - Terminal B
Terminal C is NOT used
Blue - NOT used: make safe in a terminal block
Earth - NOT used: make safe in a terminal block

Correct any wiring errors
Replace new prog stat

Remove LP722 from back plate

Move the wire connected to terminal 4 (CH ON) to terminal L.
THe LP722 will now control HW only. All control of the heating is now with the CM907. (You said CM907 earlier, I don't know of a CM703.)

Replace LP722
Turn power ON

Check system and report.