Room Thermostat

[ptaylor]

I am just finishing decorating my hall and would like to replace the thermostat. I have a normal Vaillant combi boiler but i am not sure which thermostats are compatible. I have put a picture below. I got confused because my thermostat has a Neutral, earth and live connection but a lot of them are only advertised as have a 2 wire connection? Also a lot of them now come with batteries, is this just for the LCD displays? Does anyone think that these one's below will be compatible?

Any help would be really appreciated.

[GALLERY=media, 6773][/GALLERY]

[url]http://www.screwfix.com/prods/46637/Plumbing/Central-Heating-Controls/Drayton-RTS8-Room-Thermostat[/url]

[url]http://www.screwfix.com/prods/26159/Plumbing/Central-Heating-Controls/Honeywell-T6360B-Room-Thermostat[/url]

[url]http://www.screwfix.com/prods/40819/Plumbing/Central-Heating-Controls/Honeywell-DT200-Room-Thermostat[/url]

 

[stargazer]

I got confused because my thermostat has a Neutral, earth and live connection but a lot of them are only advertised as have a 2 wire connection?[/img]

What you describe as a neutral connection may be a switched live.
Thermostats work like a light switch that turns itself on when the room gets colder. They have at least two connections – live (via your CH timer) and switched live (call for heat). Some also require a neutral connection.
You may have to look for a 2 wire version. Your middle link (Honeywell) is a 3 wire version and is the same as I have at home. It requires a neutral, live and switched live connections via 3 core and earth cable.

How many cores come from the cable in your wall and what colours are they?

 

[ptaylor]

[GALLERY=media, 6775][/GALLERY]

I have taken this picture if this helps at all?

 

[Diyisfun]

Looks like the earth wire is being used as a neutral.
With the blue wire as the return fom the switch.Mmmm

Im not an electrician

 

[BS3036]

It's also possible that the blue wire is the neutral.

'Most bi-metal thermostats require a neutral to complete the circuit that powers an accelerator heater and possibly an indicator lamp'

And the earth coloured wire is most likely an illicit switched live.

Does the unit have a part number?

 

[sm1thson]

I use to have the same thermostat and replaced it with a similar one to the ones you linked on screwfix, i dont have time to talk you through it now but this link explains what should be wired where:
//www.diynot.com/forums/viewtopic.php?t=75541 (make sure you read the text as two of the wires were the wrong way round as i found it (as pictured)).

hope you havent papered the wall.