C/H Timer wiring help please

[anothercarl]

Posted: Wed Jan 16, 2013 4:06 pm


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Hi All, Can you help please.
My house is empty and For Sale but I kept heating on cos of the cold weather. It stopped working a few days ago.

The Switchmaster SM300 clock has stopped and buzzes faintly. if I manually turn it, the 'pegs' turn Heating on and off correctly so I presume the clock motor has packed up (exactly like the last one 7 years ago). My local shop advised me there is no direct replacement and suggested a Siemens RWB27 which I bought.

The backplate on the RWB27 is set out exactly like the SM300 i.e. N.L.1.2.3.4. but the wiring diagrams on back of both timers is different and frankly I do not understand the paperwork that came with the RWB27.
(especially since the SM300 isn't listed there).

The boiler is a Ravenheat RSF 82 fanned combi and there is a Room stat.

There are 3 cables into the SM300 backplate

Cable 1 is 4 core, it has a Black to No.2, a Blue to N, a Brown to 1, and an earth.
Cable 2 has earth chopped off and a Blue (red tape stuck to it but not carefully wound around) to 2 and a Brown to 4
Cable 3 is from a fused spur, N L and Earth to their respective places.

Can supply pictures if required.

Can anybody advise me the wiring to the RWB27 pls? would like to get heat back on asap. Many Thanx Carl.


Read more: //www.diynot.com/forums/electrics/c-h-timer-wiring-help-please.351612/#ixzz2IAspadiB

 

[doitall]

Yes a pic would help.

Cable 2 we need to know. so leaving that safe for now.

The old 1 goes in 4.

The old 4 goes in 2.

The old 2 is 1

Cable 3 goes the L&N

 

[anothercarl]

Hi doitall
thanks for your help

F.W.I.W. Cable 3 is def from 240v fused spur.
I think Cable 1 is from boiler and Cable 2 from Room stat

old wallplate (sm300) in situ

sm300 wallplate

• anothercarl
• 16 Jan 2013
• 1

SM300 wiring diag

sm300 rear view

• anothercarl
• 16 Jan 2013
• 1

RWB27 wiring diag

rwb27 rear view

• anothercarl
• 16 Jan 2013
• 1

an attempt at 2 close ups

rwb27 wiring

• anothercarl
• 16 Jan 2013
• 1

sm300 wiring

• anothercarl
• 16 Jan 2013
• 1

 

[anothercarl]

forgot to answer your last question

Cable 2 blue (with red tape on) goes to No 2 which is a spare (no pin on back of sm300)
and the Brown goes to No 4

 

[doitall]

What is the make/model of the room stat.

Can you id the colours with numbers in the stat please.

I think cable 1 goes to the room stat.

 

[anothercarl]

Will go over there now. Will take me a couple hours round trip. watch this space and thanks again. carl.

 

[doitall]

Subject to your confirmation.

Cable 1

Brown to 4
Black(red tape) to 1

Cable 2

Brown to 2
Blue to 1

Cable 3 L&N

 

[matt1e]

The terminals on the switch master are
L & N
4 Is common,
1 is on
Terminal 2 is being used as a connector

Your RWB27 terminals are
L & N
2 is common
4 is on

So just follow DIA's earlier post

If cable 1 is the room stat cable then you need to disconnect the neutral to it
As your boiler has volt free switching so doesn't req it
But cable 1 could just as likely be connected to the boiler

Matt

 

[anothercarl]

Hi Guys

I see you’ve been busy whilst I was away but since I have the pics now, here they are for you to see.

Untitled

• anothercarl
• 17 Jan 2013
• 1

The cable in the Honeywell Room stat is 4 cores which presumably means its Cable 1 as there is only one 4 core cable at the SM300 timer switch and it has the same colours. Inside the room stat the Blue is on No 2, the Black (with Red tape around) is on 3 and Brown on 1 (which is actually 5th screw from left) then there’s the Earth.

Untitled

• anothercarl
• 17 Jan 2013
• 1

The connectors in the stat, from left to right are: Earth, 2, 3, 4, 1 . . . 5 and 6 are empty.

Untitled

• anothercarl
• 17 Jan 2013
• 1

wiring diag inside stat lid

I really appreciate your help guys, thank you.

 

[doitall]

Subject to your confirmation.

Cable 1

Brown to 4
Black(red tape) to 1

Cable 2

Brown to 2
Blue to 1

Cable 3 L&N

Just follow the above.

The blue in cable 1 goes to N as before

Or if it's easier.

The old 1 goes in 4.

The old 4 goes in 2.

The old 2 goes in 1

L&Ns are the same

 

[anothercarl]

Doitall . . . Thank you very very much

It's up and running . . . the jobs a good un

Thank you

Also thanks to Matt for his input.

Best Regards

Carl

 

[doitall]

Thanks for the feedback Carl, always good to know when it goes well