Replacing room thermostat

[Garp1]

My old thermostat has 3 wires (red, black, green and yellow - which seem to be live, neutral, earth). The new one has 3 ports: 1=live, 2=switched live, 3=neutral. The live and neutral are obvious; should the earth go to the switched live (call)?

Many thanks.

 

[Garp1]

Pictures of old and new thermostats.

Untitled

• Garp1
• 4 Dec 2009
• 1

Untitled

• Garp1
• 4 Dec 2009
• 1

 

[BS3036]

My old thermostat has 3 wires (red, black, green and yellow - which seem to be live, neutral, earth).

This must be a guess and can't be right, can it? If you had live and neutral coming in, there's no wire left to be an output to the thing being controlled. So it can only be live and switched live. There seems to be an unused terminal which may have been meant for a neutral, or may be a normally closed contact.

The new one has 3 ports: 1=live, 2=switched live, 3=neutral. The live and neutral are obvious; should the earth go to the switched live (call)?

So you don't have a neutral available. This is sometimes required to make the thermostat more responsive, or may be used to light the lamp when demanding heat. It may be that you need to get a thermostat which doesn't have the need for a neutral.

Whatever you do, don't connect the earth to the switched live. If the (next) new thermostat has a terminal to park the earth in, use it, else put the earth in a piece of choc block.

What are the types of the old and new thermostats so that people have more to go on?

 

[ban-all-sheds]

The live and neutral are obvious; should the earth go to the switched live (call)?

The fact you can wonder if that might be OK shows that you are so staggeringly ignorant of even the most basic of electrical basics that you have no business doing any electrical work at all.

Please get someone in who isn't going to kill people.

 

[londonboy]

You need a two core stat like the honeywell dt200.
The black is not neutral, its a switchline and should be marked up red/brown.

http://www.screwfix.com/prods/40819...ting-Controls/Honeywell-DT200-Room-Thermostat