Replacing Satchwell TLX 2259 Room Thermostat

[eas4uk]

Hi

Need some help with the wiring on a new Sunvic TLX 6501

The 2259 is wired as follows

Red wire to terminal 3
Black wire to terminal 4
Grey wire had been made safe by the look of it but not sure as it could of been on terminal 1 at some point?
Green wire to back plate terminal (earth)

Ther terminals on the 6501 are

NC, COM and NO

Im assuming live is COM, and Im not sure on the others
Do these new units not need earthing?

Any help will be greatly appreciated - thx in advance for any replies

eas4uk

 

[D_Hailsham]

The 2259 is wired as follows

Red wire to terminal 3
Black wire to terminal 4
Grey wire had been made safe by the look of it but not sure as it could of been on terminal 1 at some point?
Green wire to back plate terminal (earth)

Are you sure that the above is correct?

Does the 2259 work?

 

[stem]

The existing 2259 wiring connections are as below, with the wires you describe shown in () Terminal 1 is 'demand' this is the terminal that becomes live and switched the heating on, so there must have been a wire connected to it.
1 = Demand (Grey?)
2 = n/a
3 = Common (Red)
4 = Neutral (Black)

The Sunvic TLX 6501 is wired as follows:
1 = Common (Red)
2 = On (Grey?)
3= Off - not used in your case

You do not need the neutral connection for the 6501, so isolate it and make it safe, and definitely don't connect it to any of the terminals

 

[D_Hailsham]

The existing 2259 wiring connections are as below, with the wires you describe shown in () Terminal 1 is 'demand' this is the terminal that becomes live and switched the heating on, so there must have been a wire connected to it.
1 = Demand (Grey?)
2 = n/a
3 = Common (Red)
4 = Neutral (Black)

But in his opening post the OP said:

Red wire to terminal 3
Black wire to terminal 4
Grey wire had been made safe by the look of it but not sure as it could of been on terminal 1 at some point?

So all he has connected is Live (3) and Neutral (4); no Switched Live!

This needs to be sorted out before we can give proper advice.

 

[stem]

Based on the facts from the OP.

Red= Live (common) That's normal and exactly what I would expect
Black = Neutral again normal exactly as expected.

As terminal 1 is the switched live, it must have a connection. How else would the system work without a switched live supply? There's only one wire left which is grey, which the OP says might have gone there.

How else would you explain it?

 

[eas4uk]

Thanks for the replies everyone

Well I have wired it as suggested with the red to com and the grey to NO and it does not appear to be switching the heating on - as in set the temp to 25deg and its not firing up the boiler

I took pictures of the old thermostat before I disconnected it

I've hosted them so you can see what I mean - to my knowledge this has never been touched since we moved in 5 years ago - unless my bro has messed with it but I dont know if he has or not. The thermostat was also working back in May/June when we last used the heating.

 

[D_Hailsham]

Any chance you can post pictures of a clean stat and backplate without all the years of accumulated dust etc?

 

[eas4uk]

Hope this helps?

 

[D_Hailsham]

Hope this helps?

That's very clean. Agi would be proud.

Are you sure you have the correct terminal numbers? I was hoping they would be visible on the pics.

If you look at the wiring diagram on the stat (enlarged below), you will that terminal 3 is the live, terminal 4 is the Neutral and terminal 1 is the switched live. The small rectangle in the bottom left represents the boiler.

click to enlarge

Untitled

• D_Hailsham
• 27 Aug 2010
• 1

 

[eas4uk]

That diagram is hinged on the corner of the 2259 and corresponds with how I posted it was wired before I removed it.
On new one, I have wired the red wire which was on terminal 3 on the 2259 to the COM terminal, and the grey wire which appeared to be either loose, made good, or was on terminal 1 on the 2259, to the NO terminal. The NC terminal has no wire on the new unit and the black wire (neutral?) and the green wire (earth) have been made good but it doesn't seem to be working. I've set the temp to 30deg and turned the controls on the boiler to manual, but it is just not firing the boiler up to heat the radiators... Not sure what to try next to be honest

 

[ChrisR]

COnfirmed - grey and red go to 1 and 2 in your new stat, either way round.
If it doesn't work, wire them together and see if the boiler comes on.

 

[eas4uk]

So just to clarify:

on the new 6501 the 3 terminals that are listed

NO = terminal 1 = switched live
COM = terminal 2 = live
NC - terminal 3 = **empty**

And to test by wiring together if this configuration isn't workig - this is just into the same terminal in a conblock to ensure the boiler fires up?

Also wanted to say thank you again for everyones input so far - much appreciated

 

[eas4uk]

Well I've just rewired the old thermostat to test and the grey is certaily needed on terminal 1 for the boiler to fire so I can confirm that it is the switched live.

I've now rewired the new thermostat and its still not working so I am definitely out of ideas - I have reset the unit, checked the DIP switches but no joy - very frustrating

 

[D_Hailsham]

Well I've just rewired the old thermostat to test and the grey is certaily needed on terminal 1 for the boiler to fire so I can confirm that it is the switched live.

How did you prove this? Was it by linking grey and red together at the thermostat end? If not, how did you prove it.

 

[ChrisR]

Have you checked the batteries in the new stat?
Does it click when you set a low then high temperature?
Do you have a continuity tester to try it with?