C/H Timer wiring help please

[anothercarl]

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.

 

[EFLImpudence]

If the backplate is the same standard one can you just not fit the new timer to it?

 

[b13kal]

If you are selling the house , remove the external timers and put the link jumper back in.

That will get the heating Back on. That's your cheapest option

 

[anothercarl]

Thanks for replies guys

@ EFLImpudence: the connectors on the backplate are the same but it’s not the same backplate. The shop says there isn’t a Timer now that will fit straight on to the SM300 backplate
@ b13kal: I could do as you say or put the SM300 back on and leave it on Constant, call me a softie LOL but I like to do things right and fix it proper i.e. new working Timer.

But Thanks again for your input anyway chaps. Regards, C.

 

[b13kal]

Ok fare play

Ok since your a good man post pics of both back plates inc the wiring and ill try to help you out

 

[b13kal]

Call me sad but I just looked on ebay and found 4 why not just buy one off them and plug it in?

 

[EFLImpudence]

But the terminals are the same. Transfer the wiring.

You really need a continuity tester to find out for sure but -

Cable 1 is 4 core, it has a Black to No.2, a Blue to N, a Brown to 1, and an earth.

To boiler ???

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

This would appear to be the control wires. To Thermostat ?
The earth should be connected - plumbers???

Cable 3 is from a fused spur, N L and Earth to their respective places.

This would appear to be the 240V supply

 

[anothercarl]

Hi Guys
Just spent last 3 hours taking photos, cropping em, uploading 'em, writing replies then clicked the wrong button and lost it all.
Have had enough for tonight. Back tomorrow daytime, hope you can be too. Thanks.

 

[anothercarl]

Hi Guys

The job is now sorted, big thanx to Doitall in Plumbing forum. But also thanks to you for your help too.

Regards
Carl

 

[ban-all-sheds]

Let's hope he didn't have you misuse any conductors..

 

[Scoby_Beasley]

Cable 2 has earth chopped off.....

Let's hope he didn't have you misuse any conductors..

Too late!!