Wiring a thermostat to Baxi Combi boiler - is this the right way?

[plasteredric]

Hi Guys,

I've done a quick drawing of how I think I should be wiring in the thermostat. Can anyone take a look over it to see if i've got it right.

Cheers

 

[paul_h]

Looks about right to me, although when I tilt my iPad it's rotating the drawing so I'm looking at it side on. Only thing that might change is your L1 L2 LX connections, depends on the contacts with the thermostat, it'll either work properly, not work atol or work continually bypassing the thermostat

 

[paul_h]

Had another think I'm sure LX is usually the common , do u have the wiring diagram for your new thermostat?

 

[Anthony King]

From the look of the drawing its a Siemens stat,
And if so lx is common.

 

[plasteredric]

sorry i'm not technical when it comes to electrics, what's the common?

this is the wiring diagram from the stat



From what you've said im guessing it should be live to LX, then neutral from L1 back to boiler?

 

[paul_h]

It's not essential to get colour correct on the switching side, but for simple ness, brown LX and blue L1 as u said.

Colour/polarity must be correct on the mains side tho ..... Which as you've put brown-live ,blue-neutra

no earth as item is double insulated.....

 

[plasteredric]

thanks for all the help.

what do you mean by double insulated?

 

[Geordie Spark]

It's not essential to get colour correct on the switching side, but for simple ness, brown LX and blue L1 as u said.

Colour/polarity must be correct on the mains side tho ..... Which as you've put brown-live ,blue-neutra

no earth as item is double insulated.....

Careful there ........ The thermostat may well be double insulated, but the boiler isn't.

Don't confuse the op into thinking there is no need for an earth on the whole installation!

You know what you mean and so do I and most of the other lads will too, but we can't take it for granted that the op does.

 

[plasteredric]

oh and would it be okay to use 2 separate lengths of 3 core flex or should i really be using a 4 or 5 core?

 

[Anthony King]

oh and would it be okay to use 2 separate lengths of 3 core flex or should i really be using a 4 or 5 core?

3 core from spur to boiler, 4 core boiler to stat

 

[Geordie Spark]

oh and would it be okay to use 2 separate lengths of 3 core flex or should i really be using a 4 or 5 core?

I like to use 5 core, but I'm caught short of 5 core, then 2 lengths of 3 core neatly tie wrapped together with appropriately sized cable ties is ok.

 

[plasteredric]

I like to use 5 core, but I'm caught short of 5 core, then 2 lengths of 3 core neatly tie wrapped together with appropriately sized cable ties is ok.

Wouldn't a 5 core be excessive in this case? im assuming you mean 5 cores + earth. or does it not matter about the spare wire?

Also, should the boiler be on it's own circuit from the RCD unit?

 

[Geordie Spark]

Wouldn't a 5 core be excessive in this case? im assuming you mean 5 cores + earth. or does it not matter about the spare wire?

Also, should the boiler be on it's own circuit from the RCD unit?

It's horses for courses.

The last job I did was a wireless stat. The transmitter was stuck on the wall in a living room and the receiver I mounted in a twin back box ( NOT to be confused with a double back box ) along with the fcu so the wiring from the fcu went to the receiver to power it and then on to the boiler via 3 cores of the 5 core (LNE) leaving 2 remaining cores from boiler to receiver and return from receiver to boiler to control it.

It isn't the "only" way to do it, but in the scenario I had it was the tidiest.

My old gaffer used to say "there's more ways to choke a pig than by stuffing it with butter".


Edit ..... the boiler circuit should be rcd protected and wherever possible I used to run it on its own radial from the cu, but it can be run as a spur.

 

[plasteredric]

cheers guys, great help.

Oh, and Geordie, nice mr2

 

[plasteredric]

just a thought, would i need to put anything from the L2?

 

[paul_h]

just a thought, would i need to put anything from the L2?

No u should only need LX and L1

 

[paul_h]

Careful there ........ The thermostat may well be double insulated, but the boiler isn't.

Don't confuse the op into thinking there is no need for an earth on the whole installation!

You know what you mean and so do I and most of the other lads will too, but we can't take it for granted that the op does.

sorry mate, good point, Lol

 

[Geordie Spark]

cheers guys, great help.

Oh, and Geordie, nice mr2

Thank you.

That MR2 is a beauty - my pride & joy second only to Tidyboiler of course!

I have another MR2 in red but with an uprated engine - a 3 litre V6 but the engine needs a rebuild.

 

[Geordie Spark]

sorry mate, good point, Lol

As you get older you'll find yourself becoming more ..... pedantic ..... just like me.

 

[tidyboiler]

Thank you.

That MR2 is a beauty - my pride & joy second only to Tidyboiler of course!
.

Good save fiasco!!!!!