Wiring Confusion - Wall Thermostat (See Images)

[markyboy944]

Hi guys

I am attempting to replace my old Honeywell rotary wall thermostat with a newly purchased Horstmann one.

My problem is I don't know which wires go where, so I've tried to show the "old" wiring (together with diagram), and the new wiring.

OLD WIRING:

Untitled

• markyboy944
• 7 Mar 2009
• 1

The photo above shows 4 wires from top to bottom, and which also have terminal numbers on the terminals (on the brown plastic - not showing very well on the photo, so I've added the red numbers). These are , vertically from the top

Blue - 2
Red - 1
Blue - 4
Yellow - 3

The following sticker is shown inside the honeywell box:

Untitled

• markyboy944
• 7 Mar 2009
• 1

The letters next to each of terminals 1,2,3,4 show codes (L,N, 20(4)A , 6(4)A) so , putting the two sets of info together (i.e. the photo and the diagram), the honeywll is as follows:

1 - Red - L
2 - Blue - N
3 - Yellow - 20(4)A
4 - Blue - 6(4)A


NEW WIRING:

Can't include photo of the new thermostat, but the manual is clearly stating that (for 230v wiring [as opposed to "volt free"]) , the connections are:


SL Off - Heat Off
L - Live
SL (ON) - Heat ON
N - Neutral

So - the question is - which cables go where ? I guess using the two "tables" of info , the live and Neautral are fairly obvious (I think??) , but what about the other two ?

So .. I'm thinking

Horstmann <-->Equivalent (from old honeywell set up)
--------------- -------------------------------------------
SL Off - Heat Off <--> ?? [ 3-Yellow-20(4)A ? OR 4-Blue-6(4)A ?]
L - Live <--> 1 RED
SL (ON) - Heat ON <--> ?? [ 3-Yellow-20(4)A ? OR 4-Blue-6(4)A ?]
N - Neutral <--> 2 BLUE


(I also spotted another page in the horstmann manual which refers to "The external Thermostat loop" of the boiler. This seems to require 5 wires, so I'm assuming this isn't the relevant page (simply because the existing wiring on the honeywell is 4 wires). Am I right ?

Any help greatly appreciated - cheers - Mark

 

[ChrisR]

Well I'd say your L and N are OK, which leaves the other 2. SO which is call for heat and which is call for coolth?

It should be easy enough to establish that, with the thing disconnected. If you have a meter with Ohms or a continuity bleeper, the one you want will only be connected to Live when you turn the knob UP.

Sparks won't fly even if you connect those two wrongly - it'll turn the heating on but with the knob in the wrong place, so you just reverse them.

 

[Dick Puller]

Mark, I appears you have an extra wire (Blue on 4)??!! This is not normal & you'll need to establish what it's doing, or indeed if it's doing anything??

Normally the wiring on the Honeywell RS is;
Red Switched Live(from programmer/time switch) on 1
Blue Neut. on 2
Yellow (calling for heat) on 3

The Blue on 4 may be an earth wire being sleeved with Blue??

 

[kevindgas]

The Blue on 4 may be an earth wire being sleeved with Blue??

check if there is an earth in the cable cut back to same length of outer sheave! it may be a 4 core cable it may not

 

[namsag]

Dickpuller , have you never heard of motor on motor off motorised valves ie sunvic/satchwell.
good chance the system now how has spring return valves and the extra off wire is not req and is not connected further alone the circuit

 

[picasso]

highly unlikely that an earth is connected to 4 as this this becomes "live" when the stat switches, trace number 4 it is probably disconnected at the boiler/wiring centre.

 

[Jezclayton]

Rewire as follows:-

Existing [1] to Live
Existing [3] to SL Heat On
Existing [4] to SL Heat Off
Existing [2] to Neutral.

Namsag has hit the nail right on the head and it may well be the case that [4] is no longer connected at the wiring centre. As he says, it really depends on the zone valves currently installed, but I wouldn't stress yourself on this one.

 

[Dick Puller]

Dickpuller , have you never heard of motor on motor off motorised valves ie sunvic/satchwell....................A fair point son, but can we have the rest of your reply in English??!! Did you have any formal education??

 

[seco services]

Did you have any formal education??

still got the screwfix forum attitude then.

 

[Dick Puller]

still got the screwfix forum attitude then................And your point is son??

The part of his reply one CAN read is clearly a dig at me, so keep your big nose out!!

 

[seco services]

you don't change puller do you, you p***ed everyone off on the screwfix site now your trying it on here. sad man

 

[Dick Puller]

Why are you compelled to read my posts then???

 

[namsag]

Dickpuller i am so sorry i done a typo error and put further alone circuit instead of further ALONG.
You must be a wee bit paranoid pal as it was not a dig at you or your lack of knowledge about BASIC central heating controls and wiring. I was merely giving you a formal education in the basics.

 

[Dick Puller]

It's clear many on here have a limited knowledge or experience of the heating trade. We are still waiting for your valuable input on this thread 'sego'!!

 

[Dick Puller]

Dickpuller i am so sorry i done a typo error and put further alone circuit instead of further ALONG.................Hmmmm!!! As I say, limited education.

You must be a wee bit paranoid pal.................I wasn't paranoid until they started plotting against me!!!