Wiring a wireless thermostat

[Golan]

Good evening.

I am trying to replace and old mechanical thermostat with a new wireless digital thermostat. At the moment the system is controlled by Honeywell ST6400C Programmer,

The old thermostat is Honeywell T6360

wiring to the old thermostat is

3=N 1=L And one goes to the Earth

I am trying to replace the old thermostat with SALUS RT500RF

problem is that I can't understand the wiring diagram; also there is no option to earth in the new thermostat

I tried to connect only the L and the N but the problem is even when the thermostat suppose to stop the heating it is still keeping it on, the light on the receiver goes off but the electrical connection is not been disconnected

HELP .... :(

Thank you

[John]

>> The problem is that I can't understand the wiring diagram; also there

You should have a live, Neutral, switched feed and earth (3 cores and earth)

Have you checked to see what you have at the boiler end of the circuit?

[Golan]

I checked the wires from the thermostat to the programmer.

1 wire go to the N (CH on) 1 wire go to Live witch for some reason is connected to the wiring center 1 earth

i have no idea where to start.

may be it is not the right thermostat for the system.

[Heliotrope Smith]

There is no neutral on the old stat. Just live in and switched live out plus earth.

>> The problem is that I can't understand the wiring diagram; also there

The new wireless stat does not need an earth as there is no mains going to it. It is powered by batteries. Mains power is required at the reciever only.

What make/model boiler are you wiring up?

[Golan]

The boiler is vaillant ecomax 612 Honeywell ST6400C Programmer

i dont think ican wire a wirless thermostat in the currect configration. is there any digital thermostat that i can buy that will work with just a N and L wires ?

[John]

You are thinking wrongly - think live and switched feed. You may not have a neutral although you have a black wire.

Imagine a simple switch - it has a live and a switched feed. This is what I think you need. If you were connecting live to neutral you would get a short.

( although I think you need a neutral to make it work)

[Golan]

Can it be that the simple mechanical thermostat dose not have neutral ?

in that case is a 2 wire digital thermostat will work ??

?id=39124&ts=43139

[Heliotrope Smith]

If the existing thermostat has only two wires plus an earth going to it then there is NO neutral . The (probably red) takes the live to the thermostat (switch) and the (probably black) takes the live back to the boiler.

As long as the thermostat is volt free, yes.

?id=39124&ts=43139

[Ed Sirett]

This subject comes up at least once a week (during the colder half of the year). We need a FAQ or a wiki page on it. Some one must be able to to write down something sensible.

Modern heating controls are double insulated and require no earthing, having no metal casing or chassis. Sometimes there is a spare terminal to park the unneeded earth wire on.

[John Rumm]

OK, reading between the lines here. It sounds like someone has used ordinary two core and earth cable to hook up your old stat and has only made use of some of its functionality. In reality I would guess you

*don't have any* neutral connected to the old stat.

The old style stats work better if there is a neutral present, however they will still work without it.

Forget the colours of the wires: one will be a permanent live connected to pin 1, and the output from pin 3 will be a switched live.

With the earth, cover it in earth sleeving, and fold it back on itself. That way it is available if needed in the future. Its not needed now.

You probably connected your black wire to the pin identified as neutral in the diagram thinking it is neutral.

Instead, look at the top 230V operation diagram in the manual, you want to connect your red wire to the terminal marked L, and your black to the one marked SL (On).

For completeness you should sleeve the black wire with red at both ends to save further confusion. Both wire in the cable are live - one permanent, one switched.

[John Rumm]

Sounds like a good plan...

Your wish is my command (well sometimes) ;-) :

all we need is some content. I could shamelessly nick some diagrams from that the PDF quoted above as a handy starting point.

Fancy adding any more relevant topics to the skeleton?

[John]

>>>>> The problem is that I can't understand the wiring diagram; also there

Guys - in the instructions it clearly looks as though it needs a Neutral - as it is a wireless one it requires power. The instruction states "The unit still requires 230v feed for volt free operation." This implies 3 wires and earth.

[John]

T4360 A does not have a neutral - the connection between the stat and the "Heating Load" (the boiler) is the switched live - it is not neutral.

Please - look at the diagrams and get your terminology right

[John Rumm]

True, but we are talking about the T6360 which does have provision for a neutral connection in the A and B variants. Only the 6360B seems to actually have a use for it in that it has the heat anticipator (according to the spec table)

Indeed.

[John Rumm]

Yup, it quite possibly does for the receiver (the transmitter has battery power).

This is one of the occasions where it is actually harder to wire the wireless version than would normally be the case for a wired version!

[John]

Sorry - I got the model numbers mixed. I got a bit carried away when I saw the diagram without the accelerator.

Perhaps there is a case for ease of wiring for the receiver to be fitted close to the boiler - provided it is within range of the transmitter.

I believe the OP has a live and a switched feed (in black) are we agreed? And that the model also needs a neutral.

[John Rumm]

Yup, the original stat possibly has provision for a neutral, but it looks like it has not been installed that way. The black wire sounds like it is the switched live. (the original connections only make sense for the A and B variants of the T6360).

The new stat's receiver will need a neutral (to allow the receiver to draw power for itself). Assuming it is positioned close to the boiler this could be connected via a length of multicore control flex, rather than fixed wiring using 3&E. Alternatively the stat may currently be connected to a wiring concentrator if it is being used to control the boiler indirectly via a two or three port valve and possibly an external "programmer".

[Heliotrope Smith]

>> The problem is that I can't understand the wiring diagram; also there

Set up the receiver close to the wiring centre. Remove the wire link on the receiver. From the wiring centre find the permanent live & neutral and connect to L & N on receiver. Trace the old stat wires in the wiring centre, disconnect and do away with these and connect to COM and NO. Should now be able to set up transmitter and get things working.