No hot water on Baxi Nuvola 3 Comfort

[randomf]

Hi,

I have installed Baxi Nuvola 3 Comfort with Nest 3rd gen thermostat over OpenTherm. The heating works, however there is no hot water. The boiler doesn't come on when hot tap is opened. Any ideas?

Thank you

[randomf]

The configuration is Combi bolier of course. Tried also System boiler with no hot water control, but none of them works. When I connect the original Baxi thermostat back, everything works as expected

[Vladut]

Hi there, just checking in with you. Did you manage to check the last message?

[george_t]

Hi @randomf, thanks for reaching out. I'm sorry to hear you're experiencing this issue, but we'll sort this out together. Can you tell me please when did the situation start occurring first and when was the thermostat installed?

[randomf]

It occurred right after I installed NEST. I installed it on 29th November. The hot water doesn't work since so I had to revert to original Baxi thermostat.

[AlexD]

Gotcha. You mentioned it was an OpenTherm boiler. Did you perform the installation or was it set up by a professional installer or a Nest Pro?

While the thermostat can be set up in multiple ways I wanted to ask how the Heat Link was wired. Was it wired for an OpenTherm system or in some other configuration? 

You can have a look here at a few different installation examples.

[randomf]

I performed the install. I wired boiler's M2 pins 1, 2 (wires for proprietary thermostat, which should communicate over OpenTherm) with HeatLink OT1, OT2.

[AlexD]

Gotcha. In that case setting the thermostat to System or Combi will not have any effect. As those would use terminals 123456 for operation. Since it is a Combi boiler with OpenTherm the thermostat the thermostat would only control the temperature of the hot water, and the temperature of the water used for heating, as combi boilers provide hot water on demand. However, because OpenTherm standards can vary, your boiler might not be able to do this. If this is the case, you should be able to set the water temperature manually on your combi boiler.

Did you set the water temperature on the thermostat or do you have an option for this on the boiler? 

[randomf]

The problem is the boiler doesn't have any other controls than the thermostat which you can install on the wall or on the boiler and configure it as such. Then I can control the hot water. However both cases it occupies OpenTherm terminals so there is nowhere to plug Nest. Yes, I can run Nest in On/Off mode, however this makes the whole system very inefficient since I lose the ability to modulate the power.

[AlexD]

Gotcha. Have a look at this article here. In the last section it advises that you need to have that particular logo for OpenTherm compatibility. It is possible that the system is not fully compatible using that particular brand's OpenTherm protocol that they use, of course their particular thermostat would be able to operate it. You could perhaps check with the boiler manufacturer, it may be just a setting or something that needs adjusting. It is also possible that it may need an adapter to have full compatibility. If possible check in with them and see what they can advise on compatibility with other thermostats. 

[george_t]

Hi @randomf. Just checking in, how's it going with your thermostat? Were you able to check out the link my colleague sent me?

[AlexD]

Hey there, I haven't heard from you in a while so I'll be locking this thread. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community. Thanks, AlexD.