Replacing Room Thermostat

[chrispriddyuk]

Hi everyone.
I am trying to repalce the room thermostat.
We have a Worster Combi Boiler. I want to replace the thermostat simply coz the plastic cover on the old one is broken.
However I need some help working out the wiring.
The old thermostat is the Sunvic TLX 2259
Ive found a wiring diagram at http://www.tlc-direct.co.uk/Technical/DataSheets/Sunvic/TLX.pdf
I struggled to work out which new thermostat i needed. I wasnt after a digital one, just a bog standard white plastic jobby.
I went for a Drayton Combi Stat RTS8

The instructions say i need a 3 wire setup. This should be ok as there are three wires connected to terminals in the old room stat.
The instructions say there should be a Live, Neutral and 'N Load'

Any help on if i do actually have the correct replacement and which wires should go where.

Thanks
Chris

 

[Sarahspark]

Do you have a link to the new instructions, as' N load' sounds a little strange.The three terminals are usually L, SL (or call) and N.There is sometimes an earth terminal as well.

Sarah

 

[Space cat]

Sarah took the words out of my mouth! "Load N" is a very strange label indeed. Surely they're not switching the neutral line!

Meanwhile, take note of which wire goes where in your existing thermostat. Live is on 3, switched live (load?) is on 1 and neutral is on 4. You'll need this information when you eventually work out what's what on your new thermostat. If you subsequently mix up neutral with either of the other two, you risk blowing your programmer!

 

[Steve3948]

No what it is showing is the load schematic with a N on the other side of it.

The terminal on the other side of the load symbol is the switch live.

 

[chrispriddyuk]

Hi guys, thanks ever so much for posting
I have now located the manual for the new thermostat
http://www.invensyscontrolseurope.c...6A-4E3F-A026-625C98E429AE/0/D512CombiStat.pdf
Looks clearer in this one. Thi one marked 'N Load' also has the tag 'call for heat'
Does this help with the wiring.
I guess i need to know that the one connected to pin 1 on the old goes to the termnal marked X on the new one,,,and so on...
Thanks all. Much much appreciated.
Do I have the right stat? A combi one for a combi boiler right???
chris

 

[Steve3948]

Load on 3 (switch live calling)
Live
Nuetral

The symbol just shows that your load will require a nuetral.

Depending on your cable, normally

Red or Brown = Live
Yellow or Black = Switch Live (calling)
Blue or Grey = Neutral

 

[chrispriddyuk]

Thanks Steve I think we've cracked it

OLD stat = Purpose = New Stat
Pin 1 = Switched Live (load) = '3'
Pin 3 = Live = 'L'
Pin 4 = Neutral = 'N'

Cabling is a little strange, there are basically two bits of mains cable (as used in ring mains etc) that run from the boiler to the stat. So the colours are all red and black! Thats why i needed to work out what did what and should go where as the colours would never match up!

Thanks for all help.
Ill be back if it all blows up!
chris

 

[suffolklad]

hi chriss did the you get thermostat working then i posted same question as i also couldnt understand why it said n on the stat diagram.