topic Re: Neat 3rd Gen and Worcester Greenstar 40CDi in Nest Thermostats

Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Tue, 12 Dec 2023 03:59:12 GMT

Hello,

I have just had installed a Nest 3rd Gen thermostat so I can control my heat remotely, on my 12 year old Worcester Bosch 40CDi Combi Boiler.

Everything appears to be working just fine apart from it seems the heating pump runs continuously 24/7. Im pretty sure this should not happen, so wondering if anyone can shed some light on how I fix this issue as my friend who installed it is also unsure how to fix this.

many thanks for any advice in advance.

Neil

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

Frustratedddd — Tue, 12 Dec 2023 13:41:30 GMT

That sounds like a bit of an issue, as the thermostat is the part that turns the pump on/off! Certainly should not run 24hr, that defeats the object of having a thermostat. That means it's not wired correctly by the sounds of things.

For it to run 24hr means you have no switching, and would assume the installer has connected live neutral direct to the pump!!

What happens when you turn the stat from calling for heat and not calling? The pump still runs?

Can you upload a picture of the Heat Link wiring, and perhaps we can go from there.

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Tue, 12 Dec 2023 14:42:48 GMT

Hello. I will indeed get some photos of the wiring to post tomorrow. But just so you know the boiler does not fire up, when the nest reaches temp the boiler isnt firing, its just the pump stays on 24/7. The boiler will only fire when we need heat.

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

Frustratedddd — Tue, 12 Dec 2023 16:04:18 GMT

Well I am totally confused!

You say ''Everything appears to be working just fine apart from it seems the heating pump runs continuously 24/7'' Now you are saying '' the boiler does not fire up, when the nest reaches temp the boiler isnt firing'', so which part is working just fine?

That means to me nothing is working correctly!

What system do you have and did you follow the installation wiring diagram for your system?

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

TudorL — Tue, 12 Dec 2023 16:33:45 GMT

Hi there @neilfearnley and thanks for reaching our Community. I'm sorry to hear about this, but I'll do my best to help you out. It's best to start from a picture of the wiring done on the Heat Link, as @Frustratedddd suggested.

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Tue, 12 Dec 2023 16:53:12 GMT

Hello. It was done by a local plumber, but he wasnt seemingly too good with Nest. prior to this I had a Worcester digital room stat on my wall, connected to the boiler. Timer functions were all handles by a TP200 unit that plugs into the front of the boiler. I had absolutely no issues with it, apart from I was not able to connect remotely and turn heating on/off while out of the home. The only thing that has changed is the installation of the Nest 3rd Gen, so I think I am fair to assume something is wrong there. Ill get some pictures of wiring soon as I am back near the boiler.

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Tue, 12 Dec 2023 16:53:45 GMT

I will get some pictures soon as I am back near the boiler. Many thanks

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

TudorL — Tue, 12 Dec 2023 17:14:02 GMT

No worries, keep us posted.

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Wed, 13 Dec 2023 11:35:53 GMT

Good morning all,

please see pictures of the wiring on this link:-

https://www.dropbox.com/scl/fo/zyot0apssrn22gip76niv/h?rlkey=l9ycp64qixkhjkxyfntvrfhr2&dl=0

Hope this will help

Neil

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Wed, 13 Dec 2023 11:36:29 GMT

Wiring pics:-

https://www.dropbox.com/scl/fo/zyot0apssrn22gip76niv/h?rlkey=l9ycp64qixkhjkxyfntvrfhr2&dl=0

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

AlexD — Wed, 13 Dec 2023 12:26:06 GMT

Thank you for the pictures. Just to confirm, as the wires are very long and only 2 colours, you have 2 wires in T1/T2 that go from there to the thermostat display, 2 wires in N/L that are neutral and high voltage live wire and 2 wires in terminals 2 and 3. The one in terminal 2 being high voltage (or low voltage wire if you have a low voltage/dry contact boiler) and the call for heat wire in terminal 3, correct?

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Wed, 13 Dec 2023 12:33:58 GMT

That is correct yes

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Wed, 13 Dec 2023 13:01:23 GMT

Apparently it may not be the pump thats running. my guy says its coming from the top of the boiler, behind the units in the picture? Any help?

https://www.dropbox.com/scl/fi/t2c8bn323wn2y7wkba50f/image0.jpeg?rlkey=fyk50vdmvh46erhy108r4t8du&dl=0

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

Frustratedddd — Wed, 13 Dec 2023 13:48:48 GMT

Does terminal ''3'' at the Heat Link go to terminal Lr at the boiler?

Are Terminals ''Live & Terminal 2'' both just Live, coming from the boiler?

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Wed, 13 Dec 2023 14:07:29 GMT

Hello, from my sparky:-

Terminal 3 (n/o) does go to Le at the boiler. Terminal 2 (com) is perm feed but from Ls at the boiler

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Wed, 13 Dec 2023 14:08:48 GMT

Its looking like its not the heating pump running. Is there a fan at the top of the boiler, it could be this that is permanently running. I just assumed was the heating pump but appears not to be the case. The unit running is at the very top of the boiler.

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

Frustratedddd — Wed, 13 Dec 2023 17:21:15 GMT

Where is Le and what does that do?

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Wed, 13 Dec 2023 18:44:57 GMT

From Sparky….

Le??? I don't think there is an Le.
Boiler controls are as follows:
NS - neutral supply
LS - live supply
LR - live return (no/nc).

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

Frustratedddd — Wed, 13 Dec 2023 18:53:26 GMT

You wrote it!

Terminal 3 (n/o) does go to Le at the boiler. Terminal 2 (com) is perm feed but from Ls at the boiler

Re: Neat 3rd Gen and Worcester Greenstar 40CDi

neilfearnley — Wed, 13 Dec 2023 19:01:55 GMT

Let me get sparkys reply 🙈 sorry. Give me 10