Installing a NEST to a Vaillant Turbomax

[Dan Robinson]

Dunno. Not had to worry about it. One follows the instructions.

 

[AGAS]

FFS

 

[Luke Cameron]

Apologies for resurrecting this thread but am looking for the definitive answer to the Nest / Vaillant connections!

Can someone confirm that the 'MikeyD method' is:-

Boiler 3 to Heatlink L
Heatlink L to Heatlink 2
Boiler 4 to Heatlink 3
Boiler 5 to Heatlink N

See image below

From MikeyD's posts it sounds like there is no need to have any wires coming from Boiler L or Boiler N (this was how my previous wireless thermostat got it's power) as the boiler 3 is Live (as well as common?) and boiler 5 is an additional Neutral.

Thanks in advance for the clarification!

Thanks all!

 

[jackthom]

Yes, there’s no need for the additional power feed. The wires from the boiler 3 and 5 will do fine.

 

[Luke Cameron]

Thanks Jackthom,

I replicated what how my old drayton scr was setup as they had identical labels this gave:-

Boiler L to Heatlink L
Boiler N to Heatlink N
Boiler 3 to Heatlink 2
Boiler 4 to Heatlink 3

As far as I can see this just means I'm pulling in power in a slightly different way (possibly avoiding a fuse, so not great long term).

However I'm not seeing any control from the heatlink at all.

The boiler seems to be carrying on as if I still had a wire between boiler 3&4 (IE firing on a timing pattern controlled by the rotating knob on the boiler control panel).

I can here the relay click when I manually change the nest thermostat to either switch the heating on or off, but the boiler carries on doing whatever it was doing(either staying on or staying off..)

Any thoughts on this?

 

[jackthom]

If there’s a clock still connected at the boiler then depending on how it’s wired it could possibly override the Heatlink. Try setting the clock to permanently OFF and see what effect that has, if any.

The Heatlink certainly should work in exactly the same setup as the old Drayton scr.

 

[Luke Cameron]

Clock is set to on (sun) which is what it was on before. Will try that, but sort of expect it to just turn central heating off, the wiring diagram shows them serially, so if either is off, the boiler should not fire.

From what I'm seeing somehow, it feels like Boiler 4 (call for heat) is getting a signal at all times. (as if the loop between 3&4 was still in place). I just can't work out how!

 

[jackthom]

I would disconnect the Heatlink wire from the boiler terminal 4 to see if the live signal is coming from the Heatlink to start with. If it is check that there are no spurious links or shorts in the Heatlink wiring strip.
If necessary you might also remove the Heatlink Live supply so it is completely OFF and check that the boiler isn’t firing.

 

[Luke Cameron]

Ta, good plan

 

[louiscar]

Hmm perhaps wrong of me to revive an old thread but here I am considering getting a Nest thermostat for my Vaillant EcoTec 24. I have a thermostat on the wall but would not wish to use that as the placement is just wrong and has led to so much erractic behaviour.

Anyway I've trawled quite a few threads here and the question I have is whether the wiring (control block numbers) etc are fairly generic between the eco combi boilers?
ie. most seem to involve connecting the receiver to 3 4 5. I will take a look at mine but haven't opened it up as I haven't yet bought the device.
My Ecotec 24 was installed in 2011 as I remember and it was the most basic of all the models at the time but still looks fairly similar to the pictures posted of other models. No HW tank it's just a plain combi boiler.

I would expect (hope) I don't actually have to route out specifics for this particular model if Vailliant do things in a standard way but that is the question.

Sorry for reviving the thread but I didn't want to start yet another thread on this subject and it keeps it all in one place.

 

[ianmcd]

Better to start your own thread, yes far too many on here asking the same thing, you are correct but you need to do it if you want the correct advice, you need a single channel nest and not a dual channel

 

[louiscar]

Better to start your own thread, yes far too many on here asking the same thing, you are correct but you need to do it if you want the correct advice, you need a single channel nest and not a dual channel

Ok I'll post a new one but so far I've not seen a nest with different channels advertised - just "Nest Learning Thermostat, 3rd Generation"

such as this - https://www.amazon.co.uk/gp/product/B016PW3JSG/ref=ask_ql_qh_dp_hza

At the bottom this says "combi boilers, heat only boiler and can control hot water etc"
They appear to be adaptable now.

 

[ianmcd]

if your boiler does 240v AC switching you can use the dual channel but if it uses voltage free or 24v dc switching then you cant so safer to go for the single channel

 

[louiscar]

Ok Thanks Ian I'm going to have to look up the Ecotech pro 24 and see if I can find that out.

edit: got to say that if this is the case - the Nest "compatibility checker" is a piece of gross negligence. The questions it asks -

1) do you have a combi boiler
2) does it have a separate wired thermostat or wireless thermostat (either answer will do)
3) Congratulations nest 3rd gen is compatible.

Doesn't seem like a great check and probably quite misleading for many.

 

[ianmcd]

just get the model that is single channel whether it be nest , hive , or any other make if it is single channel it will work with any combi apart from some Worcesters