am i a dunce? nice new looking digi room thermostat.

[cockneyboy]

Alright here's my problem, if it is one? Hope someone here can help me out.

I have bought a new thermostat for my wall, a modern, nice digital one.

My old one looks crappy and was chipped (the plastic corner) so I thought i'd better sort it out.

Anyway, am i being a dunce or not: (you can tell me).

The old stat had 4 wires, the neutral, the common, the demand and the satisfied terminals.

The new one only has/requires the 2. they are common (C) and call (which is demand i imagine)?!

Basically, i presume as it is a modern one things have changed a little, so what do I do with the 2 other wires? and will the new one be ok with just the two?

cheers people for any help you can give me.

 

[gas4you]

Fit a small terminal block to them to make safe and just forget them.

I assume your new one is battery operated and so has just the 2 wires for the switch?

 

[cockneyboy]

cheers for helping. yeah the new one has a battery (i guess for the digital display). 2 wires for the switch inside are C and CALL. should it need more than this then? so the other wires are just needed to be blanked off. what at both ends or just inside the new stat?

where can i get a terminal block from? i dnt have to buy a whole terminal box do i...

 

[gas4you]

You will need to get a small strip (terminal block), 3 amp capacity and just cut off 2 that you need. Should be around a £1/£2 I would think.

You could, if you locate the wiring center, disconnect those 2 wires there and insulating tape off, eliminating the need for any block at the stat end.

 

[cockneyboy]

cheers boss. will get one.

this is a great forum. glad i found it.

 

[HarrogateGas]

I would suggest not forgetting about the two extra wires..........you proberbly have a motor open/moter close valve somewhere expecting power from those forgotton wires!!! Make sure the new stat has a satisfied terminal that switches (some dont).

You can however forget the neutral.

 

[Lectrician]

I would suggest not forgetting about the two extra wires..........you proberbly have a motor open/moter close valve somewhere expecting power from those forgotton wires!!! Make sure the new stat has a satisfied terminal that switches (some dont).

You can however forget the neutral.

Agree fully.

Your system must have required a satisfied signal from the stat, and this is why it was wired this way.

You need a stat with a change over contact, one being demand and one satisfied.

The neutral you can forget.

 

[cockneyboy]

oh right. maybe i should have got a new stat with a SAT terminal too then.

I don't have a 2 port valve that has a spring return. i have a 3 port valve. from as far as i know there is not a HEATING OFF terminal required in the programmer or from the valve wiring.

not 100% sure now though

 

[gas4you]

Standard 3 port valve will need DHW on, DHW off and CH on from the programmer to make it work, doesn't usually need a satified contact in the room stat, just the HW cyl stat.

 

[Lectrician]

Describe what you have....?

If you just have a standard Y plan 3 port, there is no need for a satisfied signal from the room stat, just the cyl stat and the HW time clock.

Maybe you could check where the satisfied is currently connected to in the wiring centre or joint box etc?

 

[cockneyboy]

sorry people, i got it wrong. ive gotta apologise.

i have 3 terminals in my old stat (why did i say 4)...

i have common, call and neutral.

i guess not many systems use the sat terminal for a room stat, only for the hot water cylinder stat (on a y plan) as mentioned.

maybe with one of those sunvic mv's which have no spring return, they need the sat terminal. (on a s plan).

so i guess i just cap the neutral at 1 end and wire the other 2 up following the wiring instructions with the new stat and job done ...?

 

[gas4you]

Yep, thats right.

 

[cockneyboy]

ok cheers, will do that now.

one last question to ask, does it matter if the other end of the old neutral wire is left connected up in the terminal box? will it affect anything?

 

[cockneyboy]

just drilled 2 new holes for the new baseplate for the room stat. shame the old ones didn't match up.. anyway, nearly there but before i completely change the wires and put the power back on, is it ok for me to leave the old neutral wire in the terminal box wired as before with the old stat?

 

[gas4you]

If has to be left there then yes, but I would prefer to see it disconnected, of failing that made safe at the stat end.