No hot water if boiler is off after reaching expected home temperature (Vaillant ecoTec Plus)

[Faybel]

Whenever the NEST is automatically set to 'ECO' or even it reaches expected temperature at home with central heating (radiators) (i.e. home temp is 19º and Nest is set to 20º and home reaches 20º), nest sets boiler to off (which is the expected behavior).

⚠️The problem comes when the above mentioned happens (nest sets boiler to off), then hot water stops working and, to make it work again, I have to set one more degree to the home temperature heating (radiators) (nest sets then boiler to ON) else, I don't have hot water at home. (it shows no error or anything so everything looks fine which of course is not)

It was working fine before installing Nest Thermostat.

Wires connection seems to be fine (N, L, 2 & 3). It has been also checked by a boiler specialist and confirmed it.

On the other hand, after contacting with Google Nest On Call Support, all phone numbers they've provided to contact Google Nest Pro installers are not working/existing ⚠️!!!

- Instalador Oficial : 632819414

- MY HOMI S.L : 617145919

- IoT : 608297721

- Energea : 935631550

- Autonomo Informático : 937741917 / 606387288 / 670256213

- Domonetio : 932418083
- Drones Análisis de Datos : 608682015
- Buo Home : 618252032
- Insum : 644514811 (not existing anymore)

[Frustratedddd]

I assume you have a Combi boiler, or do you have a system boiler?

Are you an oil boiler by any chance?

[Faybel]

Hello @Frustratedddd , first of all thanks for answering 🙂

To be honest, I don't know if it is a Combi boiler or system boiler.

It is a mix (water and temperature) gas boiler, similar to this one : Gas Vaillant ecoTEC plus VMW ES 246/5-5 (https://www.bauhaus.es/calderas/vaillant-caldera-ecotec-plus-vmw-246-n/p/24394183?gQT=2) - Not sure if exactly same model, but as simple view, yes.

Anyway, let me share a pic about the current configuration/installation done, maybe is something wrong in there...

Thanks in advance !

[Frustratedddd]

Who installed the thermostat, plumber/electrician yourself etc.?

Has the thermostat just been installed?

Have you got a Hot Water tank like an immersion heater tank?

Are you saying, you want to be able to call for H/W from say the app for example and JUST the H/W comes on without the heating?

[Faybel]

Who installed the thermostat, plumber/electrician yourself etc.?

Nest Link has been installed by boiler specialist. Not Nest Pro (because it is imposible to contact them), but a guy that has been installing boilers during the last 50 years and, as per what he said, he installed other brands.

Has the thermostat just been installed?

Thermostat has been installed like 3 weeks ago and since then, I'm facing this issue.

Are you saying, you want to be able to call for H/W from say the app for example and JUST the H/W comes on without the heating?

Exactly. Before installing Nest, independently of having the heating ON or OFF, I had hot water at home. If boiler was 'off' (because I was not using heating, like in summer for instance), if I wanted to take a shower, boiler was turned 'on' automatically just to give me hot water.

Now, I only have hot water if the boiler is ON because of the Nest (because nest is not in ECO or reached expected internal temperature, that is when it sets the boiler 'off').

[Frustratedddd]

Mmmmm!!! Best get the boiler guy back in that case, as connections 4-5-6 are not connected for H/W!!!

The connections you have are only for the Heating contacts, and that would mean the only way for H/W would be to do exactly as you are, raising the Heating temperature to get the boiler to fire up. That in turns heats the water, not the best idea in the middle of summer!

When you get him back, I would suggest he removes the Earth coloured core currently connected as a ''Live'' [Terminal 2] and replaces with a Live/Brown coloured core, and then use the earth for protection of the cable installed, of which you have none!

I hope that make sense

[Faybel]

Hello @Frustratedddd ,

When the boiler guy did the installation, I've commented to him that the Nest instructions where saying that connections 4-5-6 were for hot water, but he said that they are not used. Later on, when the assistance came ('cause I've called a week or two later the gas assistance that I've contracted) they've said that everything seems OK on the connectivity.

On the other hand, I've asked a cousin and a brother in law that have nest since months ago how is their connectivity, and this is what they shared. They have it the same way I have, but not facing the issue I'm facing.

Also, as per what I've seen yesterday in different Youtube videos about Nest installation in Vaillant boilers, seems that the connections 2-3 should be connected to 24V = RT instead to the Burner off (current installation).

This is my current installation ⬇️

Youtube Video #1 : https://www.youtube.com/watch?v=rzTWLUCc8tQ

Youtube Video #2 : https://www.youtube.com/watch?v=Yrz21W5HDQU

Both cases are NOT specified in videos as for NEST, but as standard wifi thermostat. Anyway, they are not using Burner Off connections, else 24 V = RT.

I've also asked ChatGPT to see if it can give me some hint and what is suggesting is the same change, from Burner Off to 24 V = RT ⬇️

[Frustratedddd]

You have not answered this question just to confirm.

Have you got a Hot Water tank like an immersion heater tank?

Have you a tank in the loft also?

[Faybel]

No, I have not a hot water tank, neither a tank in the loft. I think it is a mixed boiler as commented in my 2nd post:

To be honest, I don't know if it is a Combi boiler or system boiler.

It is a mix (water and temperature) gas boiler, similar to this one : Gas Vaillant ecoTEC plus VMW ES 246/5-5 (https://www.bauhaus.es/calderas/vaillant-caldera-ecotec-plus-vmw-246-n/p/24394183?gQT=2) - Not sure if exactly same model, but as simple view, yes.

---

[GabrielaG]

Hi Faybel,

Thanks for reaching out to the community. I'm sorry to hear your Nest thermostat isn't functioning properly in your boiler when the Vaillant Ecotec Plus hits room temperature. I'm happy to assist you right now.

I see that you contacted Nest Thermostat support by phone. They advised contacting a Nest Pro technician, but the number was incorrect. You can Find a Pro to install your Nest products. online.

Feel free to keep us posted if you have more questions.

Regards,

Gabriela

[Faybel]

Dear @GabrielaG ,

thanks for your message. Unfortunately, not only ALL Nest Pro technician I've tried to contact are not working anymore or existing, but also the link you've provided says that there is no technician near my zone.

It is very disappointing finding out that all the ones appearing in Nest website are not working or deprecated phone numbers.

[Faybel · Accepted solution]

SOLVED!

Finally, I've followed the instructions from Youtube & ChatGPT (links & screenshots on previous messages) about Nest installation in Vaillant boilers, changing the connections 2-3 to 24V = RT instead to the Burner off and the problem got solved. Now, if the boiler is off (because it reached internal temperature at home, eco or even because I want it to be off), I have hot water.

Connections now are:

Thank you @Frustratedddd  for your kind support!