Fitting a Nest-heat link control to Ideal Logic plus 35 boiler

jackrratt

jackrratt

jackrratt

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Hi :)

I'm trying to fit a Nest-heat link control to my Ideal Logic plus 35 boiler. It should not be hard but I'm confused about the 'call for heat' wire! Yes, I know I should call a professional and may do, but first want to see if I could do it... No harm in just asking :)

The picture below is that of my current wiring with what I think needs to be done. Is this correct? Also if so, the main thermostat can this be replaced where does it get the 12v from on that as this looks like it sends 230v back to that?

IMG_1353.JPG


Many thanks in advance :)

 
your thermostat would have a relay on it with 230v passing to the 'call for heat' when it is below setpoint.

wheres the 12v from?

edit: have you got wiring diagrams - whats the picture of there?
 
Hi Dava, the Nest guide states that you should only connect the Thermostat base to a 12v wire i.e. the T1 & T2 connections on the base. the wire that goes back to the Thermostat in the pic above shows 230v. Also, would the suggestions work re above i.e connection the black wire to "call for heat" and leaving the grey and black wire to go back to the thermostat?
 
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you can't use a standard thermostat with it by the looks of it? the heatlink speaks wireless to the nest to demand it what to do?
 
No, sorry, maybe I'm explaining it very badly. I want to replace current old Honeywell thermostat part with the Nest thermostat too, my issue is that the Nest thermostat needs 12v power. given the picture above do I remove the grey wire (as this goes into my call for action on heat link) and leave in the back 230v wire which io believe would power the new thermostat (Nest needs 12v power)?
 
ok so the grey and black - 1 should go into common and 1 should go into call for heat which closes the link between the 2 terminals to call for heat. (or link live into the common and black into call for heat and disconnect grey for both ends)

the permanent feed to the heatlink will want doubling up with the L/N and from the heatlink T1/T2 to your nest thermostat
 
So here is what I understand... any help much appreciated :)


From the bottom in picture wire-in side.....

1) Current Earth = Remove Not Needed
2) Blue = Remove Old Wire Add Blue Wire To Heat Link N
3) Brown = Remove Old Wire Add Brown Wire To Heat Link L
+ Jump L (Brown) from Heat Link to Heat Link 2 Connection Slot
4) Black = 3 Connection Slot on Heat Link (Call to heat)

Bits I'm unsure about...

Remove Old black wire seen in picture (as this now goes to heat link 3 call-to-heat slot side)
Leave in 230v grey wire (which goes back to Honeywell at the moment?) but does Honeywell not need a N?

Nest thermostat
1) Replace Honeywell Thermostat with Nest using L and N for power (must be 12v).
 
the blue (N) and brown (L) are the permanent feed for the boiler aren't they? so you want to keep them in but double up and take to the heatlink terminals

what thermostat is the honeywell one? is the 230v currently coming from that aswell to power the boiler supply?
 
Dava said:
the blue (N) and brown (L) are the permanent feed for the boiler aren't they? so you want to keep them in but double up and take to the heatlink terminals

what thermostat is the honeywell one? is the 230v currently coming from that aswell to power the boiler supply?
Click to expand...

Cool the blue (N) and brown (L) are the permanent feed for the boiler so that makes sense, thanks. I'm not sure what honeywell I have but I was hoping to replace it using the power suppliy. just checked it out tho and it seems to be powered by batteries (Doh!) the wires going in must be the heat on switch which I assume cannot be used.
 
you could fit the nest there with them 2 wires and take new wires to the heatlink for the heat demand (meaning routing them wires or joining them through to terminals T1/T2 on the heatlink)
 
It tells you how on page 31 of the manual

Oh and the call for heat contacts are volt free so dont put 230v there or you will fry the pcb.

You need 230v from the fused spur to the boiler and 230v to the heat link then 2 wires from the opentherm connector in the boiler to the 2 opentherm terminals in the heatlink, you also need to move a connector in the boiler but thats in the manual page 31

Nest will then control everything

No need for the 12v wires just use the USB adapter supplied
 
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Ok, so this in my final look at how I can achieve getting 12v power using the existing Honeywell CM707 wires (this will be replaced with Nest) as suggested by Dava, can anyone just take a final look at the image to make sure there is nothing MAJOR messed up here?...

1) Leave existing Earth, Blue and Brown wires but take a new Blue N and Brown L to the N and L on the Heat Link.
2) On the HeatLink jump a new wire from L to 2 (common) (no need to connect to brown as shown in the picture do at heat link instead)
3) Remove the two Black and Gray wires seen in the picture and connect them directly to the heat Link T1 and T2 as these will be used for 12v power once the Honeywell CM707 has been removed.
4) connect 3 (call to heat) from the heat link to the connector seen in the picture where the black wire was/is in the picture.
5) where the grey wire WAS/IS (marked at 380v) on the picture --- leave as is?? OR connect to L **** STILL UNCLEAR, sorry.

Honeywell CM707

1) remove Honeywell, currency only 2 wires are connected these will now be coming from T1/2 on heat link supplying 12v I think.
2) connect the base to the new t1/2 links for power

done





draft.JPG
 
Dava said:
you could fit the nest there with them 2 wires and take new wires to the heatlink for the heat demand (meaning routing them wires or joining them through to terminals T1/T2 on the heatlink)
Click to expand...


Just an update. Sorry if I'm being a pain on this forum, but help is always appreciated!

The picture below shows what I have done (not tested it :().

As for the heat-link (not shown) I have linked incoming Live (L) with common (2). The old (L) gray and back wire (old call to heat) I will be linking directly to the T1/2 on the heat link which will supply the 12v power. For the wire I have used thick heat resistant 3 core type.

So, will I go BANG on switch on? Answers wlecome please :)


New

v1.jpg



Old wiring

old.jpg
 
Both call for heat on the boiler (last 2 blocks on your pic) need to go to 5 and 6 on the heatlink. But im still unsure why you are not wiring it as opentherm as i said before then nest will adjust boiler temperatures to what it needs to get up to temp then modulate the boiler to save gas.

it does work and everything is there in the boiler to use it.
 
Thebug said:
Both call for heat on the boiler (last 2 blocks on your pic) need to go to 5 and 6 on the heatlink. But im still unsure why you are not wiring it as opentherm as i said before then nest will adjust boiler temperatures to what it needs to get up to temp then modulate the boiler to save gas.

it does work and everything is there in the boiler to use it.
Click to expand...


Hi Thebug, I did read your command re opentherm, which looking at it now seems the better option. However, I have no idea where they are existing on my boiler. Do you have the same boiler? How do you have it connected?
 
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