Converting to a programmable room thermostat

[dstill]

Hi, my house has two separate heating zones, one for the ground floor and a second for the 1st and 2nd floors. The ground floor thermostat had two wires going to it and I have successfully changed that thermostat to a programmable unit. However, the thermostat for the second zone currently has 3 wires going to it but I want to use the same programmable unit as I did for the ground floor zone.

This is the unit I want to change it to.

http://www.ebay.co.uk/itm/201039723434?_trksid=p2060778.m2749.l2649&ssPageName=STRK:MEBIDX:IT


Is it possible given that it currently has 3 wires connected to it?

Thanks in advance and please excuse my ignorance.

 

[andytw]

What do you want to change it FROM ?

 

[dstill]

The current one is an old programmable room stat but it has three wires connected to it, brown, grey with a blue sleeve and black with a brown sleeve. The brown also has a link wire going to another terminal in the existing thermostat. (photo of existing stat below)

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• dstill
• 14 Mar 2015
• 2

The programmer I fitted to my ground floor only needed two wires and I want to use the same type on my 1st floor.

 

[andytw]

What you want to install is battery powered. It is probable that what was installed took power from the cable. To be able to assist you more you need to specify what the original programmer model is, rather than just "an old programmable room stat".

andytw

 

[dstill]

Yer, the new one is battery powered. The existing one is a Siemens RDE programmable thermostat. That's as much as I can see, there's nothing else written on the unit such as a number.

 

[andytw]

What are the markings for the connections on the baseplate from left to right. The second from the left is marked 'L', I can see that.

andytw

 

[dstill]

Hi andytw,

Thanks for your ongoing help, I do appreciate it.

1st one is marked N, 2nd one as you say is L (which has a link wire to the 3rd connection) and the 4th one only has a number which is 014.

 

[andytw]

The wire on N is Neutral and is used to allow the programmer to run itself from the mains. You will not be using this wire. It should be terminated safely.

Connect your new programmer to the other 2 wires, those on Live and the connector you called O14. I think you will find it is Q14.

There is a manual here http://w3.siemens.co.uk/buildingtec...al-controls/documentation/documents/rde_d.pdf

I have been referring to it but it does not show the wiring of the actual backplate, as such, but it can be worked out once we know the markings on the plate.

I think your programmer is a RDE10 as that is what it says on the backplate in your photo.

Trust that helps.

andytw

 

[dstill]

That's fantastic andytw, on closer inspection it is a Q rather than a 0, my eyes aren't what they used to be!

I'll now be able to get this sorted, you've been a great help mate, thanks again.