GLOWWORM FLEXICOM 30cx and Nest v3 thermostat

[Brianas]

Hello all
i have the GLOWWORM FLEXICOM 30cx combination boiler, i have bought the Nest V3 smart thermostat , i have wired up the boiler and the thermostat as far as i know correctly from the diagram with the nest instructions


This is the fused power switch to the boiler the white sheathed cable to the lower left was to the boiler , the upper left mains cable is the mains feed to the fused box.
(ignore the white cable center top to bottom right - its the same wire as to the boiler but curved up from inside the back box)

this is the terminal block from the boiler , i now don't have the brown and blue that are seen on the "24v Eb us 0V " as they were to power the old timer/thermostat

This is the diagram i have followed from the instruction manual

The issue i have is that the combi boiler is obtaining power as the unit powers up and the display panel is illuminated , and when i turn on the hot tap , i get hot water (its a combi boiler)
BUT i do not have any central heating control , i cannot get it to fire up at all
Am i missing a wire somewhere, ?
i do not understand the diagram - do the lines above terminal 1-2-3 represent its switches between one and the other ?

To add misery to this , i have found a leak in the boiler and i am to collect the new part tomorrow so i have left it for now ( the coldest day of the year )
Any help appreciated
thanks

 

[picasso]

Have you connected 3 in the heat link to R on the boiler ?

 

[Brianas]

Have you connected 3 in the heat link to R on the boiler ?

Hi Picasso

firstly thank you for such a fast reply

NO .......... but since posting i have just found this link,

https://www.cnet.com/uk/how-to/how-to-set-up-a-nest-thermostat-in-the-uk/

It re enforces your comment , the video , though ive had to watch it a few times, shows a different way to wire the system together that makes sense to me. And indeed as you say there is the wire to the R terminal on the boilers wire block. (the brown sheathed black wire)

all in all i think ive got it wired exactly as the diagram which gives no indication to wire to the "r" terminal but as i say the video makes it clear , reinforced by your comment

i have left it now for the day especially as when i pressure up the central heating it splashes water all over, ive ordered a part online to collect tomorrow and fit in the evening , once that's done i will put the wire as you and the video explain , then i will feed back the results

if it woks as wired in the video , then the diagram must be wrong and misleading - or i am too thick to understand it , but to labor a point the video makes it clear to me , the main difference is the mains power is coming from the permanent live within the boiler to the net unit and not from the fused box as the diagram is interpreted by me.

Brian

 

[jackthom]

Deleted

 

[picasso]

No Idea what your watching in the video but the diagram you posted is the right one, as I said before 3 in the heat link goes to R which switches the boiler on.

 

[stem]

If I read your first post right, it sounds to me as if you have removed the cable supplying 230V mains supply to your boiler. Anyway, below is the wiring information the Flexicom cx boiler manual:



Based on the above, I would install the Heatlink like this.



You can power the Nest Thermostat by either using a plug in power supply, or connecting the Heatlink terminal T1 to the Thermostat T1 and connecting the Heatlink terminal T2 to the Thermostat T2 and

 

[picasso]

The op has hot water so there is a good chance there is power to the boiler he has also removed the wires to the 24v supply.

 

[stem]

I thought I would show IMHO the simplest way to connect them for a DIYer, no additional links or anything to make, and I got the impression the OP was confused after watching the different videos. I got confused about what the actual situation was as there were pictures that didn't seem relevant any more etc.,

So. I though start from scratch with a nice simple installation, hopefully the 24v wires are still there, but not connected so nice and easy to put back.

 

[Brianas]

Hi all
Thank you for all the input . I have now got the system working as should. As Picasso said I was missing the link from terminal 3 in the heat link to the R on the boiler terminal block .
I disconnected the thermostat wires from the boiler block as it is 24 volts (I think) and the nest says only concept it to the 12v terminals in the heat link . Having said that it would work wirelesslying if plugged in by the supplied plug adaptor .
I will sit and draw a diagram of the wiring and post it here
Thankfully I didn't need to go anywhere near gas so I am assured that the system integrity remains
Brian

 

[stem]

Good! glad to hear you got it working.

I disconnected the thermostat wires from the boiler block as it is 24 volts (I think)

The 24v refers to the voltage generated by the boiler that can be used for control purposes as it was by the original thermostat, and would have still have been if you had connected it as per the diagram I did for you earlier. [The way you have connected it is fine BTW. There is more that one way to connect the Nest to your boiler]

and the nest says only concept it to the 12v terminals in the heat link.

The Nest Thermostat has to get 12v from somewhere to power it. It can get this from either the plug in power supply as you have done, or by connecting it to the 12v terminals that is provided by the Heatlink for this purpose. This is completely separate to, and has no connection with the 24v used by the boiler.

 

[Raming]

Hi,

Have you got diagram of your final installation.

I am replacing existing wireless thermostat (climapro2) to nest.

Thanks

Hi all
Thank you for all the input . I have now got the system working as should. As Picasso said I was missing the link from terminal 3 in the heat link to the R on the boiler terminal block .
I disconnected the thermostat wires from the boiler block as it is 24 volts (I think) and the nest says only concept it to the 12v terminals in the heat link . Having said that it would work wirelesslying if plugged in by the supplied plug adaptor .
I will sit and draw a diagram of the wiring and post it here
Thankfully I didn't need to go anywhere near gas so I am assured that the system integrity remains
Brian

 

[stem]

What boiler are you wanting to connect the Nest to? if it's a Glowworm Flexicom like the OP, I did a diagram for connecting that to Nest earlier in the thread.



I believe that the Climapro2 will be connected to the boiler ebus terminals, so wired in differently to the Nest.

 

[Raming]

What boiler are you wanting to connect the Nest to? if it's a Glowworm Flexicom like the OP, I did a diagram for connecting that to Nest earlier in the thread.

View attachment 133072

I believe that the Climapro2 will be connected to the boiler ebus terminals, so wired in differently to the Nest.

Thank you for a response.

It is a Flexicom 30cx

I was thinking to remove wires from the existing wireless receiver and wire to Nest 2 and 3 terminals.
And power nest with supplied plug and cable.

Is it workable scenario?

Thanks

 

[stem]

If the Climapro2 is connected to the boiler 'ebus' terminals. Then Climapro2 wiring should be removed and the new thermostat wired in as per my diagram. You can't connect the Nest to the ebus terminals. It needs to go to the 24v and 0v terminals.

The Nest 230v mains supply should also come from the same fused spur as the boiler, so that the entire heating system is isolated when it is switched off.