Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is ON

[rojroj]

Some time back I posted a query in this Forum about Boiler either ignoring the Room Thermostat or the Programmer.
I was suggested (by doitmyself and others) to get the Sunvic MoMo 3 Port Valve replaced by a Honeywell.
After getting this done (Honeywell V4073A), the Boiler is now completely ignoring the Programmer.
Whenever, the room stat is calling for Heat, the Boiler turns ON (irrespective of whether the Programmer is ON or OFF).
I have programmed it to be OFF between 10 pm and 6 am. However, whenever the room temp drops below 18 deg Centigrade around midnight (I've set the Thermostat at 18 deg C), the Boiler fires up. I've also tried switching the Programmer to OFF position during the day while the Boiler is running and it made no difference (Boiler kept running).
The Programmer is a Honeywell 6400C with 3 On/Off and 7 day setting.
The Room Thermostat is a Honeywell (Electronic)

Anyone seen this type of problem or has any ideas ?

Thanks and Regards

 

[PlumbBobBob]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

sounds like a wiring issue to me. who changed the 3 way valve? maybe you should get them back to sort it out

 

[so-solar]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

it sounds like the stat has been wired straight in to the link in the boiler making the programmer redundant! basically the stat is working as an on off switch?

 

[Blackcatgas]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Are you using a sundial type wiring centre? have you cut the link inside it yet?.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Sorry for the delay.

Problem 1 :
I haven't checked with a multimeter. However, with a tester, I can see Full Voltage (Glow) on the Red wire of the Thermostat (Contact 1) irrespective of whether the Programmer is On or Off. That suggests that it has a Permanent Live ? The 2nd Contact is not wired. The 3rd Contact (Yellow) also glows, but faint.
Shouldn't the Red only have 230 V when the Programmer is ON for CH and Yellow 0 V until the Stat switches it Live (the room temp falls below the set temp) ? If this is true, then it explains why would the Boiler start even if the Programmer is OFF (because of the Permanent Live).
But where is the small Volt on Yellow coming from ?

Problem 2 :
As long as the Programmer is ON for CH, the Boiler / Pump is ON even if the Stat is not Calling for Heat. Is this because of the fact that the Valve is getting its Live directly from the Programmer ?

Both these problems were present before I got the Valve replaced by an Engineer, so I don't think he wired it incorrectly. He must have done a straight replacement connection for the 5 wires (replacing Sunvic with a Honeywell). However, he did mention that the Pump didn't have the Ground connected and he grounded it.

I agree that this must be an incorrect wiring as sometimes it is the Stat which controls the Boiler (when the Programmer is OFF) and at other times it is the Programmer which runs it ignoring the Stat (when the Programmer is ON).

I would like some help from you guys in finding out what is wired wrongly and how do I diagnose and correct it.
I must admit that I have no Plumbing / Central Heating background but do have an Electrical Engineering background, so should be OK with the Electricals.

Thanks for all your contributions so far.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

The Room Thermostat is a Honeywell (Electronic)

Which model?

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Sorry the Stat is a Wired Drayton Digistat 1 (2 cells) and the Programmer is a Honeywell 6400C with 3 On/Off and 7 day setting and the Boiler is a Potterton Suprima.
On the Stat, Only 1 (red) and 3 (yellow) are connected.
On the Programmer, apart from the Ground, 5 wires connected :
Live, Neutral, HW ON, HW OFF, CH ON
Note that the CH OFF is not connected.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

YOu said earlier that you have a Honeywell thermost; the Digistat is Drayton!

Have you tried changing the batteries in the stat? See the instructions for info how to do this.

The programmer wiring appears to be correct; the CH OFF terminal is not used.

You say you have an electrical background. It's time to get your hands dirty.

Do all the components connect into a large junction box (wiring centre)? If so you can easily check the wiring using the diagram below. Although it shows a neutral connection to terminal 2 of the T6360 Room Stat, you should not connect anything to T2 on the Digistat.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Thanks doitmyself. It was my mistake - it is actually a Drayton. Yes, I've recently changed the batteries. All the connections appear to go towards / come from the backplate of the Programmer. I'll check against your diag. Thanks again for the diag.

Today morning I found that both the Red & Yellow on the Room Stat were having low Volt (tester lit dimly) when the Programmer was Off and the Boiler didn't fire. However, on turning the Programmer ON (CH), full Volt appeared on both Red & Yellow (with the Stat removed) and Boiler Fired up.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Today morning I found that both the Red & Yellow on the Room Stat were having low Volt (tester lit dimly) when the Programmer was Off and the Boiler didn't fire.

Testers are not reliable! I think you need to invest in a multimeter.

When Programmer is CH OFF there should be 0 volts on the thermostat.

However, on turning the Programmer ON (CH), full Volt appeared on both Red & Yellow (with the Stat removed) and Boiler Fired up.

You should get 240V on the wire from Programmer to the thermostat, but nothing on the other wire as the thermostat acts as the switch between the two wires. Check the wiring of the backplate and make sure there are no shorts between the terminals - stray strands of wire etc.

 

[Avatar]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

sounds like a wiring problem most likely - or a problem with the programmer itself.

Many electicians i know would not like working on a heating system like this . . .

The guy i do work with, has specaily skilled himself to work on these old systems (dont presume as an electrican you will know what to do - it is a plumbing system after all)

I work alongside my electrican, he would isolate and test each component with a MULTIMETER. I can tell him wether the plumbing components are responding properly - he can tell me if the component is wired correctly and responding to the call of the programmer and any stats . . .

It sounds like you are using guess work here. If you called someone in just to replace the three port valve, then you are paying for your presumption - which is the mother of all **** ups remember!!!

Never never never call a tradesman in, and tell them what to replace, cause you dont have a leg to stand on.

If you do, and it is a bad call, then you have to pick the phone up and call them back 'to assess and fix the problem' . . .

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

I have taken the Programmer out from the Backplate / Wiring Centre and checked that there are no loose strands. The Ground connection to the Programmer terminal was almost open (at the back plate).
With the Programmer disconnected, there is no Power to either Red or Yellow of the Room Stat. Red IS connected to the Red terminal of the backplate.
It is a Honeywell make and it says at the top "If using Programmer (not basic TimeClock) Cut Link 1". On mine, Link 1 is intact (not cut).
So, is it a 'basic Time Clock' and not a Programmer then ? Or do I need to cut Link 1 ?

It also says that only Switched Live (S/L), Neutral & Earth needs connecting for Basic Boilers ; however all 5 (L, S/L, N, E & Pumped Live) are needed for Pump Overrun Boilers.
Mine is a Potterton Suprema 40. Is this a Basic Boiler then ? I have a bypass pipe with a stopcock just between the Pump and the 3 way mid-position Valve though ?
If mine is a Basic Boiler, the Boiler connections seem to be wrong, as it has Switched Live, Earth and Pumped Live connected but Neutral not connected.
So, do I need to disconnect the P/L and connect the Neutral ?
On the other hand, if it is a Pump Overrun Boiler, then Neutral and Live should be connected too ?

Please help as I am confused.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

So, is it a 'basic Time Clock' and not a Programmer then ? Or do I need to cut Link 1?

It's a programmer - cut link 1.

Mine is a Potterton Suprema 40.

Not a basic boiler; it's a pump over run boiler.

I have a bypass pipe with a stopcock just between the Pump and the 3 way mid-position Valve though?

That's needed for the pump over run.

 

[street elbow]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Hi,

Just a thought or two.

1, you said that the red wire to the room stat is always live,

2, you say that if you take the programmer away from the back plate the red wire to the stat is dead.

3, you say that the programmer has three on / off.

4, 3 on / off programmers confuse more people than I've had hot dinners.

5, has one of the on / offs been set so it come on for 23hrs 59min rather than 1 min?

6, reset your programmer so it comes on / off at five min intervals ie on (1) at 10.00 off (1)at 10.05 on (2) at 10.10 off (2) at 10.15 on (3) at 10.20 off (3) 10.25. This will allow you to see if the programmer is working correctly over a short time period, and take out any miss timing of the ons and offs.

after trying this, re programme to the times you want, If you only want two on/off make sure that the on and off for the third on/off are set to the same time ie on at 13.00 off at 13.00.

Also make sure that off 1 is set to off before on 2 comes on and so on.

Hope this is of some help.

David.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Thanks 'Doitmyself' and 'David' for your inputs.

David, you can ignore your points 3 - 6 as I am confident that it is not the case. I have set the 2nd on / off both to 12:00 so, basically using only two. And I can see the Programmer CH Light comes on and off consistently at exactly the same times that I've set (07:00 / 08:30, 16:30 / 21:30).

What I've noticed is that the Boiler and Pump Firing is not consistent.
First thing in the Morning (07:00), the Boiler Fires as it should. However, later on, it ignores the Stat (as long as it is ON there is Volt on both the Orange and White of the Valve and the Boiler fires).
The Grey on the Valve is always Live. Orange and White are always the same - either both are Live or both are dead (so there is no switched Off). Sometimes the Stat makes both of them Live (even when the Programmer is OFF) and at other times the Programmer does the same (turns both Orange and White Live even when the Stat is not calling for Heat).
And both the Red and Yellow on the Stat are Live when the Programmer is ON and mostly Live when the Programmer is OFF (I have seen it dead for brief interval though).
If I open the Stat from the back plate, it cuts off the Boiler.

The Programmer might be faulty, but I would like to rule out the Wiring issues before I start changing the Programmer and the Stat.

Doitmyself, if you are saying that I actually have a Programmer (as opposed to Basic Timeclock) and a Pump Overrun Boiler (as opposed to Basic Boiler), then I should cut the Link 1. Should I also change the wiring for the Boiler Terminals in the Wiring Centre to match that for a Pump Overrun Boiler, ie connect the Live and Neutral from the Boiler to the wiring centre ?
Is there any risk in cutting the Link 1 and carrying out the wiring changes for the Boiler Terminals in the Wiring Centre ?
Have I made it clear what sort of a Wiring Centre I have ? It is a honeywell, but unfortunately it doesn't have a Model No. There are screwed terminals and they are labelled (HTG Valve, Room Stat, Cyl Stat, Programmer, Boiler, Pump, Mid Position / HW Valve, Mains - clockwise from left to right). I can send a diagram if you want to ba absolutely sure.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Doitmyself, if you are saying that I actually have a Programmer (as opposed to Basic Timeclock) and a Pump Overrun Boiler (as opposed to Basic Boiler), then I should cut the Link 1.

1. As you have a mid-position valve, which means you have control CH and HW times independently, the ST6400C should be configured as a Programmer.

2. The Potterton Suprima is a Pump Overrun Boiler

Should I also change the wiring for the Boiler Terminals in the Wiring Centre to match that for a Pump Overrun Boiler, ie connect the Live and Neutral from the Boiler to the wiring centre?

Is the boiler fed from a separate mains outlet to the wiring centre? If so, this is wrong as it could be dangerous. It does not matter which way round you connect, i. e mains to W/C to boiler or mains to boiler to W/C.

Don't forget the Earth connection!

Is there any risk in cutting the Link 1 and carrying out the wiring changes for the Boiler Terminals in the Wiring Centre?

No.

Have I made it clear what sort of a Wiring Centre I have ? It is a Honeywell,

Like this?

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Yes - that is the one ! No wires connected to the HTG Valve Terminals.

Is the boiler fed from a separate mains outlet to the wiring centre? If so, this is wrong as it could be dangerous. It does not matter which way round you connect, i. e mains to W/C to boiler or mains to boiler to W/C.

Sorry I don't understand the above question. I can see a bunch (all the cables under a single thick white insulation) of wires coming through the wall (assume from downstairs) and going to the Terminals marked Boiler (along with another bunch going to the Room Stat Terminals). I assume they are coming from / going to the Boiler downstairs.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Sorry I don't understand the above question. I can see a bunch (all the cables under a single thick white insulation) of wires coming through the wall (assume from downstairs) and going to the Terminals marked Boiler (along with another bunch going to the Room Stat Terminals). I assume they are coming from / going to the Boiler downstairs.

Sorry for the confusion. You have answered my question in the above info.

There will not be any wires connected to the HTG VALVE as you have a Mid-position valve, which connects to the block on the other side.

The following links should be cut: L1; L4; L5; L6.

The pump Live wire should connect to the P/L terminal of the boiler block.

There should be five wires going from wiring centre to the boiler

W/C Boiler L to Boiler Mains L
W/C Boiler N to Boiler Mains N
W/C Boiler E to Boiler Mains E
W/C Boiler S/L to Boiler Mains SwL
W/C Boiler P/L to Boiler Pump L

Boiler Pump N and E are not used.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Thanks doitmyself.

On mine, the following are connected in the W/C :

Room stat : 1 - Red (Not Live when Programmer disconnected) ; E- Earth ; 2 - Blue ; 3 - Yellow
Cyl Stat : C - Red ; 2 - Blue ; 1 - Black ; E - No Connection
Programmer : HW Off - Yellow ; HW On - Black ; CH On - Brown ; E - Earth ; N - Blue ; L - Red (always Live)
Boiler : L - No Connection (always Live) ; S/L - Yellow ; N - No Connection ; E - Earth ; P/L - Red
Pump : L - Brown ; E - Earth ; N - Blue
Mid Pos Valve : Earth - Earth ; Brown - No Connection ; Grey - grey ; Blue - Blue ; Orange - Orange ; White - White
Mains : L - Red ; N - Blue ; E - Earth

On the Room Stat : L / 1 - Red ; Sat / 2 - No Connection ; Call / 3 - Yellow

On the Programmer : E - Earth ; N - Blue ; L - Red ; Yellow ; No Connection ; Black ; Brown

On the Valve : Blue - Blue ; Grey - Grey (Always Live) ; Orange - Orange ; White - White (Both Live / Dead together)

Links : Only 4 & 5 are Cut. 1 & 6 are intact.

I have highlighted the ones which I understand are wrong in Red.
And I have marked in Bold the ones which might need checking.
Could you kindly check and confirm. Sorry for asking again and again, but you know I don't understand this and am totally relying on you and so want to make sure that you get the full picture (as you have not physically seen it).

Also,

1) If I cut the Links first, do you think some of the problems might go away. I would like to do it in steps and then observe the behavior. I guess we can revert back the Links by soldering, if needed.

2) Is the Red Wire going to the P/L Terminal for the Boiler in W/C correct ?

3) Should both Orange and White on the Valve always be the same (either Live or Dead). Are they Switched Lives - one for the Boiler & Pump ?

Thanks again for your hand holding.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Thanks for the info, Unfortunately colours don't really mean anything as there is no standardized wiring schema for heating systems; every installer has his own way of doing things. But here goes.

Room stat : 1 - Red (Not Live when Programmer disconnected) ; E- Earth ; 2 - Blue ; 3 - Yellow

The Red should only be live if the programmer has turned heating ON

Programmer : HW Off - Yellow ; HW On - Black ; CH On - Brown ; E - Earth ; N - Blue ; L - Red (always Live)

But CH ON (brown)should be the same colour as Room stat 1 (Red)! Are they two separate cables joined together somewhere?

Boiler : L - No Connection (always Live) ; S/L - Yellow ; N - No Connection ; E - Earth ; P/L - Red

But there should be wires from Boiler L and N to the boiler. You need to check at the boiler what is connected to the L, N and E terminals.

Mid Pos Valve : Earth - Earth ; Brown - No Connection ; Grey - grey ; Blue - Blue ; Orange - Orange ; White - White
Mains : L - Red ; N - Blue ; E - Earth

Wow! Something is correct!

On the Room Stat

: L / 1 - Red ; Sat / 2 - No Connection ; Call / 3 - Yellow

Which stat do you have (make and model)?

On the Programmer

: E - Earth ; N - Blue ; L - Red ; Yellow ; No Connection ; Black ; Brown

Which programmer?

On the Valve

: Blue - Blue ; Grey - Grey (Always Live) ; Orange - Orange ; White - White (Both Live / Dead together)

Grey should not always be live.
What do you mean by "Both Live / Dead together"?

Links

: Only 4 & 5 are Cut. 1 & 6 are intact.

1 and 6 will have to be cut, but not until we have sorted out my queries above!

Should both Orange and White on the Valve always be the same (either Live or Dead). Are they Switched Lives - one for the Boiler & Pump?

Ah! Is this what you mean by "Both Live / Dead together"? If so it's wrong.

Orange and White do not both have to be the same. The orange is switched live for the boiler, but White (and Grey) are control signals to the valve.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

But CH ON (brown)should be the same colour as Room stat 1 (Red)! Are they two separate cables joined together somewhere?

This is just a wire connecting the W/C CH On Terminal to the Programmer CH On Terminal.

But there should be wires from Boiler L and N to the boiler. You need to check at the boiler what is connected to the L, N and E terminals.

Shall check and confirm the Boiler connections.

The Stat is Drayton Digistat 1.

The Programmer is a Honeywell 6400C with 3 On/Off and 7 day setting.

These connections must have been wrong from when the System was installed by the Builders and all the people living in this house for the last 10 - 12 years simply lived it with :-( I wouldn't think anyone (plumber) who doesn't know what he is doing would ever tamper with the wirings !

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

This is just a wire connecting the W/C CH On Terminal to the Programmer CH On Terminal.

Of course they will be different colours; don't know what I was thinking of.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Have checked the boiler - it's a bit difficult to figure out what has come from where.
After removing the Front Left Side Cover, this is what I see :
There's a sort of Junction Box with seven points (this white junction box is screwed with 2 screws).
On the base it is marked as below

L N E Sw L N L E
PUMP MAINS

From one set of wires the connections are to the MAINS Terminals : Blue - N , Brown - L , Earth - E

From the 2nd set of wires the connections are to the PUMP Terminals : Blue - L , Blk - Not Connected , Brown - Switched Live (under Mains) , Earth - E

However, the diagram at the back side of the Front Panel says :

o o o o o o o
Earth No Contact Neutral No Contact Perm Live Sat Call Pump Live Out
(Blue) (Brown) (Red) (Yellow)

The white junction box could have been screwed / wired the other way round ( eg, the Earth is the Right most rather than the Left most)

Also, there is a another set of 4 junctions inside the Wall (covered by a plate) just by the side of the Mains Power switch of the Boiler (just below the Boiler).

Does this make any sense to you ?

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Sorry, the post was not very clear, so one more try :

L N E ................................................... Sw L N L E
PUMP .......................................................... MAINS

o ............. o .................. o ....................... o ................. o ............
Earth .... No Contact .... Neutral (Blue) ..... No Contact .... Perm Live (Brown)

........... o .......................... o
.... Sat Call (Red) ..... Pump Live Out (Yellow)

Also there is another sticker just above the 7 point terminal junction which says :

Programmer Wiring ....... CH OUT ....... DHW OUT ......... DHW OFF OUT

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

There's a sort of Junction Box with seven points (this white junction box is screwed with 2 screws).
On the base it is marked as below

L N E --- SwL N L E
PUMP----- MAINS

That's the connection block you use.

From one set of wires the connections are to the MAINS Terminals : Blue - N , Brown - L , Earth - E

What do the other end of these wires connect to? It should be the boiler terminals of the wiring centre.

From the 2nd set of wires the connections are to the PUMP Terminals : Blue - L , Blk - Not Connected , Brown - Switched Live (under Mains) , Earth - E

So the Blue is being used as a Live, which is not a good idea. The other end of the Blue wire should connect to the Boiler P/L terminal in the wiring centre.

The other end of the Brown wire should connect to the Boiler S/L terminal in the wiring centre.

The white junction box could have been screwed / wired the other way round ( eg, the Earth is the Right most rather than the Left most)

Very unlikely to be wired incorrectly. But if you want to check, the internal wire colours are:

Pump
L - Yellow
N - Blue (linked to Mains N)
E - Green/Yellow (linked to Mains E)
Mains
SwL - Red
N - Blue
L - Brown
E - Green/Yellow

There is a another set of 4 junctions inside the Wall

This is used when the optional programmer is mounted in the boiler.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

So, the Sw / L should be part of the Mains ?

What do the other end of these wires connect to? It should be the boiler terminals of the wiring centre.

Not sure, as the set of wires that connect to the Boiler Terminal in W/C have a Red (connected to P/L) and Yellow (connected to S/L). Also, I'm not sure if they are going / changing colours via any of those 4 junctions inside the wall (used for optional programmer).
Or are you talking of the other Set which is connected to the PUMP terminals of the Boiler (I thought that would go to the Boiler Terminal in the W/C (and not the set that connects to the MAINS)

So the Blue is being used as a Live, which is not a good idea. The other end of the Blue wire should connect to the Boiler P/L terminal in the wiring centre.

Does the Neutral here (PUMP terminal in the Boiler) not need to be connected ?
The S/L at the Boiler terminal in the W/C has a yellow wire ? Where is this coming from ? Also where is the Red wire connected to the P/L in the Boiler terminal of the W/C coming from ? The Blue from the Boiler PUMP terminal is not connected at the W/C end.

Pump
L - Yellow
N - Blue (linked to Mains N)
E - Green/Yellow (linked to Mains E)
Mains
SwL - Red
N - Blue
L - Brown
E - Green/Yellow

The wires going out of the other end of the Connection Block in the Boiler match these colours, although I've not checked where they are going inside the Boilers.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

The diagram below should answer all your questions. I have given comments below.

So, the Sw / L should be part of the Mains?

It doesn't matter which cable the wire is in, as long as it connects to the right place!

the set of wires that connect to the Boiler Terminal in W/C have a Red (connected to P/L) and Yellow (connected to S/L).

See diagram for where they should connect at the boiler

Also, I'm not sure if they are going / changing colours via any of those 4 junctions inside the wall (used for optional programmer).

Don't understand. Which 4 junctions inside the wall?

Or are you talking of the other Set which is connected to the PUMP terminals of the Boiler (I thought that would go to the Boiler Terminal in the W/C (and not the set that connects to the MAINS)

I can see where you are getting confused, as was the installer. If you use the wiring centre the main supply connects to the the W/C Mains terminals. Everything else gets its mains supply from the wiring centre. So the boiler's "mains" comes from the L, N, E terminals of the W/C Boiler terminals. The same is true for the programmer and pump.

Is there a switch or fused spur on the wall near the boiler? Does this turn the power to the boiler on? Does it also turn the programmer on?

Is there also a switch/fused spur near the wiring centre? What does this turn on?

Does the Neutral here (PUMP terminal in the Boiler) not need to be connected?

No. This is because the pump is connected to the wiring centre and gets it neutral and earth connection there.

The S/L at the Boiler terminal in the W/C has a yellow wire ? Where is this coming from ? Also where is the Red wire connected to the P/L in the Boiler terminal of the W/C coming from ? The Blue from the Boiler PUMP terminal is not connected at the W/C end.

I can't even guess where these wires are coming from. Do you have a multimeter and know how to use it?

The wires going out of the other end of the Connection Block in the Boiler match these colours, although I've not checked where they are going inside the Boilers.

Then you can assume that the block is correctly wired.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Don't understand. Which 4 junctions inside the wall?

As I said earlier, there is another set of 4 junctions inside the Wall (covered by a plate) just by the side of the Mains Power switch of the Boiler (just below the Boiler). ------ which you said were for the optional Programmer mounting in the Boiler.

Is there a switch or fused spur on the wall near the boiler? Does this turn the power to the boiler on? Does it also turn the programmer on?

Yes there is a fused spur on the wall just below the boiler. This turns the Power ON / OFF for BOTH the Boiler and the Programmer.

Is there also a switch/fused spur near the wiring centre? What does this turn on?

No there in NONE. The Programmer / Wiring Centre Power is controlled from the fused spur on the wall just below the boiler.

So, with the above wiring in place, do the Links 1 & 6 still need cutting ?

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

As I said earlier, there is another set of 4 junctions inside the Wall (covered by a plate) just by the side of the Mains Power switch of the Boiler (just below the Boiler). ------ which you said were for the optional Programmer mounting in the Boiler.

Got you: my mistake, I was referring to the 4 terminals inside the boiler used for connecting the optional programmer. The blocks you found in the wall could be the connection to the spur and up to the wiring centre. They may explain the differing colours for e.g Switched Live (S/L and SwL) etc.

Yes there is a fused spur on the wall just below the boiler. This turns the Power ON / OFF for BOTH the Boiler and the Programmer.

No there in NONE. The Programmer / Wiring Centre Power is controlled from the fused spur on the wall just below the boiler.

How many wires are connected to the Boiler terminal block in the Wiring Centre

So, with the above wiring in place, do the Links 1 & 6 still need cutting ?

Yes.
You cut link 1 because you have a programmer.

If the pump is connected to the wiring centre, you cut link 6 because you have an overrun boiler.

If the pump is connected directly to the boiler, there is no need to cut link 6.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

How many wires are connected to the Boiler terminal block in the Wiring Centre

Just 3 :

S/L - Yellow - Should this be the Brown Wire from the SwL (Mains) Terminal of the Boiler ? ;

E - Earth ;

P/L - Red - Should this be the Blue Wire from the Live (Pump) Terminal of the Boiler ? ;

L - No Connection (always Live) - This must be getting it's Power from the Internal Wiring of the W/C - Should this be connected to the Brown Wire from the Live (Mains) Terminal of the Boiler ? ;

N - No Connection - Should this be connected to the Blue Wire from the Neutral (Mains) Terminal of the Boiler ? ;

So, am I correct in assuming that the Live Power comes from the Fused Spur (in the Wall below the Boiler) to the Live (Mains, not Pump) Terminal of the Boiler (via the Brown Wire from inside the Boiler) and then goes to the Live (Boiler) Terminal of the W/C ?
If so, where am I currently getting my Live on the Boiler Terminal of the W/C with no wires connected ?

Also, is the Live Input to the Wiring Centre (Red) Live coming directly from the Fused Spur in the Wall or should it come via the Terminal Block in the Boiler ?

Yes.
You cut link 1 because you have a programmer.

If the pump is connected to the wiring centre, you cut link 6 because you have an overrun boiler.

Is this irrespective of the wrong connections ? Or shall I correct the wiring first ?
What I am trying to find out is - will cutting Links 1 & 6 make it worse with the wrong connections or better ?

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

S/L - Yellow - Should this be the Brown Wire from the SwL (Mains) Terminal of the Boiler ?

Yes. They must join somewhere - possibly one of the terminal blocks in the wall

P/L - Red - Should this be the Blue Wire from the Live (Pump) Terminal of the Boiler?

Yes. Again they must join in a terminal block

L - No Connection (always Live) - This must be getting it's Power from the Internal Wiring of the W/C - Should this be connected to the Brown Wire from the Live (Mains) Terminal of the Boiler?

1. Yes it gets power internally
2. If the boiler is getting power directly from the fused spur there is no need to connect this terminal to the boiler mains L

N - No Connection - Should this be connected to the Blue Wire from the Neutral (Mains) Terminal of the Boiler?

See 2 above

E - Earth

Not sure why this is connected; the boiler should be earthed at the Fused Spur.
Can you find the other end and say what it is connected to?

Am I correct in assuming that the Live Power comes from the Fused Spur (in the Wall below the Boiler) to the Live (Mains, not Pump) Terminal of the Boiler (via the Brown Wire from inside the Boiler)

That's what appears to happen. If you have a meter you can verify this

and then goes to the Live (Boiler) Terminal of the W/C?

But you have said there is nothing connected to the Boiler L terminal in the W/C and there doesn't need to be

If so, where am I currently getting my Live on the Boiler Terminal of the W/C with no wires connected?

You answered this question yourself earlier. The W/C Boiler L, N and E terminals are fed by the internal wiring from the W/C Mains L, N and E terminals.

Is the Live Input to the Wiring Centre (Red) Live coming directly from the Fused Spur in the Wall or should it come via the Terminal Block in the Boiler?

It doesn't matter. It would appear to be coming from the fused spur. which is OK. There is no need to change it.

It would be a good idea to check out how the wires are linked together in the terminal blocks behind the wall.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Thanks doitmyself. Shall sort out the Wiring issues first.
Unfortunately I'd have to go on an overseas trip for about a month, so will probably leave it until the New Year.
Shall post an update once I am back.

 

[doitmyself]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Shall post an update once I am back.

Please post update to this topic.

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Sure .

 

[rojroj]

Re: Boiler starts whenever the Room Stat calls for Heat - even when the Programmer is

Sorry for not being able to get back to this for so long - got involved with so many things after returning back.
Are you still tracking it ? If so, we can check the Wirirng issues. Let me know so that I can post a short summary to avoid you trawling through it all again.