Replacing a room thermostat

[SamNotSpam]

Hi, looking for some advice please!

I currently have an old three-wire Potterton room stat that I'm replacing with a Siemens RDJ10. The stat is linked to a Honeywell ST6400, and I want to override the CH timer controls on this. This is then linked to my ancient Stelrad Ideal Excel RS60 (1980's model, not the newer one).

My question is, what wiring do I need to change? As it stands the new stat is just ignored by the boiler, so I assume there's another step needed. I've already used the forum to correctly wire up the new stat (common to LX, switched live to L1, neutral not used and terminated). I'm attaching a picture of the current wiring pattern, the grey one is the one that goes to the room thermostat if that helps:

Any ideas/advice gratefully accepted, thanks!

 

[doitall]

Unfortunately you should have asked first instead of assuming every boiler is the same.

Post the details about the system. and make/models.

Is it an Y plan (3 port valve)

Can you put the old stat back and show the connections in the wiring center.

 

[SamNotSpam]

I haven't changed any of the wiring in the unit pictured, all I've done is swap the old thermostat for the new one. I'm fairly sure I've stated the make/models of all the components in my original post - what am I missing? Finally, it's not Y-plan, there are two separate actuators for the CH and HW.

Thanks.

 

[doitall]

Very helpful, where is the orignal and what name was it under, and why start another thread.

The grey wire should be a permanent live.

The brown in the mv is the call from the room stat.

The orange is what tell the boiler to work.

 

[SamNotSpam]

I don't understand what you're on about, I haven't started a new thread! I really don't get your snarky attitude, you don't have to help if you don't want to, I suggest you log off and have a nice cup of tea/beer to calm down.

Anyone else want to help please?

 

[doitall]

I was trying to help, but I need information, and can't see anywhere it say you have an S plan.

You did say the grey goes to the room stat which it doesn't.

 

[SamNotSpam]

My old room stat has four wires going to it - earth (not attached), blue (neutral), red (live) and yellow (switched live). These are encased in a grey outer sheath. Since the ONLY red wire in the wiring box also comes from a grey outer sheath, I'd have thought it a reasonable assumption that the wires encased in that sheath are connected to my room stat. Please enlighten me as to your theory!

 

[doitall]

My old room stat has four wires going to it - earth (not attached), blue (neutral), red (live) and yellow (switched live). These are encased in a grey outer sheath. Since the ONLY red wire in the wiring box also comes from a grey outer sheath, I'd have thought it a reasonable assumption that the wires encased in that sheath are connected to my room stat. Please enlighten me as to your theory!

When one refers to the colour they usually mean the wire not the outer sheath.

So the yellow goes to the brown in the MV.

The red looks like it's connected to the earth wire, does that correspond to terminal 4 in the programmer.

 

[SamNotSpam]

Apologies, I didn't realise I wasn't being clear . Yes it does, the CH On terminal.

(I have to go on a customer callout for an hour or so, I'll try and keep up with this on my phone if I can).

 

[doitall]

Have you got a multimeter and know how to use it safely.

If so is the 230vac on the red wire when the htg is calling.

The red wire goes to LX in the new stat.

 

[SamNotSpam]

Sorry for the delay; yes, it is, so I'm connecting that to LX (which confirms my original wiring of the new stat was OK at least!) and the yellow (H on the old stat) will be L1, is that right?

 

[doitall]

Yes, the yellow to L1.

Remove the yellow from the wiring center and check for 230vac when the heating and stat is calling.

IF there is remove the orange from the wiring center and check that. that will be the orange from the htg MV to make it clear.

 

[SamNotSpam]

OK, voltage on the yellow but not the orange.

 

[doitall]

OK, voltage on the yellow but not the orange.

May have confused with my last post.

Did you put the yellow back in the connector before checking the orange.

 

[SamNotSpam]

Yes, I did.