Boiler / Thermostat wiring

[plumberdan]

I need some help on the wiring for a Drayton thermostat and wiring into a Procombi HE. The wiring from the Combi manual and thermostt is as shown in the attachments.


My concern is that the boiler diagram is showing 4 wires : NL 2 3, but then the thermostat diagram is only using 3, N L 2 OR 3. Is this thewrong type of thermostat for this boiler ? My electrical skills are no problem,my understanding of boilers is very limited.

Thank you for reading, any help will be appreciated.

 

[ShaunCorbs]

Have you got a timer/clock ??

Live and natural to room stat and connection 3 from the room stat to the 3 port on the choc block from the left

( if the boiler supports 240v controls)

 

[plumberdan]

Thank you for your reply. Do I leave those 2 wires already in choc block 3 shown in the boiler diagram ?

 

[ShaunCorbs]

Thank you for your reply. Do I leave those 2 wires already in choc block 3 shown in the boiler diagram ?

Do you have an external clock ?

 

[plumberdan]

Yes. To explain a little further, I followed the boiler drawing, chock block 1 (from the left) originally went direct to the second terminal shown on the external time clock. I removed this and redirected it into 2 on the thermostat, and ran from 3 on the thermostat back to the 2nd terminal on the time clock. It blows the fuse when the contacts close in the thermostat.

 

[ShaunCorbs]

Yes. To explain a little further, I followed the boiler drawing, chock block 1 (from the left) originally went direct to the second terminal shown on the external time clock. I removed this and redirected it into 2 on the thermostat, and ran from 3 on the thermostat back to the 2nd terminal on the time clock. It blows the fuse when the contacts close in the thermostat.

Right what time clock you got ?

 

[plumberdan]

My apologies, the timeclock is integral to the Procombi HE, not external.

 

[ShaunCorbs]

You got a pic of your room stat please ?

 

[plumberdan]

Hope this is ok.

 

[ShaunCorbs]

Hope this is ok.

View attachment 25534

Model no ??

 

[plumberdan]

Sorry .... Drayton combi stat 24028.

 

[Stu Davis]

Most combi's have two wires looped inside the facia for the room thermostat. I would use L & 2 on your stat. Some times just as simple to fit a Salus digital room thermostat.

 

[plumberdan]

Thank you both for the advice so far.
There definitely were no looped wires in the facia.
The combi manual asks for a "voltage free" thermostat, which I have. Not following the boiler manual schematic may cause me all sorts of headaches, although I appreciate the schematic seems not to work anyway, I have checked and triple checked my additional wiring so I know it is correct, although the schematics in the thermostat are only using 3 of the 4 terminals the combi manual schematic says t block.o use, is it possible I have totally the worng type of thermostat ?
I cannot identify the "call for heat" wire in the combi manual, and even if I could, I would have no idea what wire to leave out in the combi choc block

 

[ShaunCorbs]

try moving the wire from terminal 2 on the boiler to no 3, as normally

1 is live from the boiler
2 is hot water pre heat
3 is heating call

 

[plumberdan]

Thank you for your replies. I have done some more investigating of the choc block and the thermostat and I am concerned about the fact that both contacts 2 and 3 of the thermostat output 240v when the thermostat switches.
When I check the choc block connectors 1 and 2 of the appliance drawing (from the left), they don't seem to be 240v when the heating is running.
I it possible the integral timeclock reduces the voltage? I am concerned about using the 240v output from the thermostat for far of blowing the electronic board in the boiler.
Is there a thermostat that just switches without outputing 24v0v ? Is tis the "voltage free" type of thermostat I need ?

 

[newcastle phill]

Doesnt that boiler like volt free and that stat doesnt.
Check compatability

 

[plumberdan]

Thank you for your reply Phill. I think that could be the issue yes, the boiler needs "voltage free" type (from the manual), but I cannot determine if the stat is or isn't voltage free. That's basically the reason for my posting, I can't find any "recommended" stats for this boiler.

 

[newcastle phill]

Any 2 wire volt free stat will do

 

[plumberdan]

I appreciate the reply phill, and without asking for recommendations, can you advise at leas t a few commercial basic thermostats that can be used.

As a side note, is the Drayton I advised in an earlier post no good ?

 

[newcastle phill]

Drayton rts4 would do
And Basically any 2 wire battery operated stat.

As I say im not familiar with that stat but it doesn't look volt free.
Call plumcentre or other merchants as they will have something on the shelf

 

[plumberdan]

Thanks again for the helpful advice, I have also been in contact with Vokera technical, and their reply was :

"The boiler switches on a 240v Neutral so you will have to use a volt free device, which would normally only be two wires."

So when using the " 2 or 3 wire" terminology, is this 2 or 3 including the 2 needed for the 240v operating supply ?

Any idea of the "call for heat" terminal on the choc block of the boiler diagram ?

 

[ShaunCorbs]

Thanks again for the helpful advice, I have also been in contact with Vokera technical, and their reply was :

"The boiler switches on a 240v Neutral so you will have to use a volt free device, which would normally only be two wires."

So when using the " 2 or 3 wire" terminology, is this 2 or 3 including the 2 needed for the 240v operating supply ?

Any idea of the "call for heat" terminal on the choc block of the boiler diagram ?

depends as some take the live from the supply and just send voltage back to appliance

l and n and then separate to supply side common and out