Nest Thermostat Combi Boiler Hot Water Control

5euros

I have a Nest Thermostat installed. There are two zones heating and hot water. I can control the heating, but don't seem to be able to control hot water only. If the Nest setup is set to Combi boiler I can't even see separate hot water controls. If I change the setup to "System" then I can see the hot water control on the thermostat and the app,but they don't work with the boiler. Is it possible to get the separate hot water channel working with my configuration?

standardg60

I would assume the hot water temp has no connection to the thermostat at all, just set the temp on the boiler itself.

MagicBusDriver1

You should see a separate Hot water icon in the app but my combi is connected by opentherm. I can change the hot water temperature. Does the hot water work when you turn on a tap?

whizbang

I thought Version 3 of Nest could also control hot water, maybe you need to upgrade..

rightjob!

Do you have a combi or system?

if you have a combi what are you trying to control on the hot water side? The combi takes care of that,you set the combi hot water temperature and that’s it.

if you have a system boiler-do you have 2 zones already or one zone?

5euros

Thank you all for the comments.

Physical set-up

I have a Glow-Worm combi boiler Energy7 18s. I can switch between heat & hot water and hot water only using a physical valve near my hot water cylinder. The heat & hot water together works perfectly. I have only 1 zone in the house (heating & hot water or hot water only).

Software set-up

I have a Nest Thermostat 3rd generation. When "equipment" is set to "Combi" I only see the heating control. When I change the setting to "System" I can see a separate Hot Water control on the app on my phone. However, this has no affect on the boiler (i.e. the boiler remains off when I try to switch on the hot water from the app). If I change the equipment setting to OpenTherm I get a warning stating that O/T is not detected.

So I'm trying to understand:

a) Can I have separate software controls for the heating and hot water or must I run everything from the heating part of the app? It would be nicer to have a time schedule for the hot water in the summer, rather than a temperature control. But maybe that isn't possible.

b) Is it possible that the wiring of the heating control next to the boiler is incorrect?

Thank you for your advice.

standardg60

Are you saying that the only hot water you have is that in the hot water cylinder OP?

That's not how a combi boiler works, it should kick on once you turn the hot tap on and heat the water as you need it.

Sounds like it's been installed to a traditional CH set-up.

5euros

Hi @standardg60, Yes, we have a traditional central heating setup. The combi boiler replaced the original gas boiler.

standardg60

Sort of defeats the purpose of having a combi then but anyway..

You would only have heating control then as it's the heating that's heating the water, there isn't a separate control for it, so in Summer you'd switch the valve to hot water only and use the app to turn on and off the heating.

5euros

Thanks @standardg60 , at least now I know.