New thermostat not turning central heating OFF

[Savo]

Hi,

I have a Worcester greenstar 28i junior combi boiler and a tower rf wireless thermostat that I purchased from toleration which I am trying to install to replace the wired British gas one.

The wires connected to the old British gas one were brown to the L terminal, blue to the N terminal, black to the 3 terminal, and the grey wire had just been cut and was not connected to anything.

I spoke to the tech team at Worcester and Tower who both said to connect the live and neutral but then connect the black wire to the terminal 4 (labelled "NO" - switch output on normally open) and then use a piece of wire to connect terminal 4 back to the L terminal. This worked and the wireless thermostat turned the central heating on but is not turning it off so the thermostat says the room is 23 degrees and the target us 21 degrees. The "active" light on the receiver was on until it hit 21 degrees then it correctly went off but did not switch the central heating off.

I'm guessing something is wrong with the wiring so it is constantly in the on position but not sure what I've done wrong. I have attached the wiring table to this post in case it helps.

Any advice would be very much appreciated.

Thanks,

Ian

 

[stem]

Indeed. What you have done won't work, the black wire is the switched live wire controlling the boiler and you have connected it to the permanent live terminal with a link, so the heating will therefore be permanently on.

There are several models of Towerstat and they have different connection / terminal numbers. Is yours like the table below? [If not post back details of your terminals or thermostat model]

If your is as above, then:

Connect the Brown to the Live terminal
Connect the Blue to the Neutral terminal
Connect the Black wire to Terminal 4 NO

The wire link should be between L and COM [Not L and 4]

Edit: I notice you say that you had included the "wiring table" in your original post, but unfortunately I can't see it.

 

[Savo]

Hi Stem,

Thanks very much for the response. Apologies, but my post seems to have been added twice within a few seconds of each other (I tried to change the title as I misspelled Central Heating in my original post and appear to have added it twice). Somebody has replied to the original post so it is now resolved but you were correct - the diagram you added is exactly the same as the one that came with the Thermostat. I wired it up the same way as you described above and it worked perfectly. Blue-Neutral, Brown-Live, Black-NO (Terminal 4) and then just used a piece of wire to join L to COM (Terminal 3). The boiler now seems to be going on and off correctly when the signals are sent by the thermostat so I'm hoping that this is now resolved.

Thanks again for your help and clear instructions.

Ian

 

[stem]

Ah, OK thanks, I didn't see the other post that had already been answered as I accessed this one from the 'unanswered threads' tab. Anyway, glad you got it sorted.

 

[Savo]

No problem - I did try to delete the other thread but couldn't find anywhere to get rid of it, but now you've answered it I'll leave it as it is as it might be useful to anyone else who made the same mistakes I did.

Thanks again.

Ian