Thermostat connection.

[Tom123]

Hi and happy new year

So I bought this mechanical-thermostat and it has 4 connection points, but my boiler allows only for 2 connections (or only live conductor)...

I've connected 0.6mm to point 1 and 3 on thermostat, but because I'm doing it for the first time is it right ?

Wiring diagram at the bottom

Also are, 2, single core-separated, clipped direct to a wall cables not an issue (by the means of induction or maybe volt drop (20 meters total length)) ??

 

[NozSpark]

Terminals 1 and 3 are the correct ones for permanent live and switched live, however you should really be connecting the neutral as well,,,, you should really also be taking an earth to it even if you put it in some terminal strip.

You say you have used 0.6mm single core cables to connect to the thermostat,, this is not a standard size, what is it? You should be really using something like 1.0mm 4 core heat resistant flex so long as the boiler is protected by a 3A fuse.

 

[batty]

I generally use 1mm flat three core and earth to wire room stats all coonections are available at boiler. If you don't have a neutral connection to boiler when its needed temperature will creep out so it won't work very well. You could always get a stat that doesn't need a netrall connection like a siemens but as Noz says cables should be earthed its part of wiring regulations and don't forget boiler electrics are notifieable.

 

[Tom123]

Ok, this cleared up some things.

What is a connection '2' or 'Satisfied' do ?

 

[NozSpark]

Terminal 2 tends to be used on what is called "Y plan" systems where there is a valve which diverts the hot flow pipe to the immersion cylinder or to the radiators

 

[batty]

Live will go to com and switched live to demand if it works back to front just switch connections round. Basically its a two way switch.

 

[SteveT]

Ok, this cleared up some things.What is a connection '2' or 'Satisfied' do ?

On Cylinder stat you may have Common (Feed) Calling © Satisfied (NC) + Earth

When stat on Cylinder is </= set temp C will be live, actuator on mid posistion 3port valve will be in DHW (or W) posistion (or Mid if room stat also calling for heat i

once Cyl temp >set temp, NC will become live and actuator will move to CH or H position diverting heat from cylinder

 

[Doc Hudson]

Don't forget that new central heating control wiring is notifiable under Part P building regulations. So you will need a building regulations compliance certificate to be issues as well.

Doc H.

 

[Tom123]

I will not install it myself. I'm just trying to educate myself with electrical aspects as it is part of my study course (EPE) so it can help a bit.

What I found was there is no Neutral connection in the boiler, can I connect a thermostat's neutral with respect to earth ?

 

[NozSpark]

No you can't use the earth terminal as a neutral connection

You would need to find a neutral terminal; there will be one, otherwise the boiler wouldn't work