Netatmo Smart Modulating Thermostat - Compatible combi boilers

[pajeffery]

We currently have a Netatmo Smart Thermostat and a combi boiler, we have also invested in smart valves for each room. This thermostat has no control off the hot water, just central heating.

We are now going through a building extension and need to upgrade the boiler, Netatmo have a new smart thermostat that can control hot water, but I'm trying to understand what boiler would be required.

They state that the boiler needs to be Opentherm compatible with an integrated hot water tank, for us would that mean a storage combi boiler (Not just an ordinary combi boiler)

 

[MNW67]

Why do you want to control the hot water on a combi boiler with a smart thermostat. Are you just talking about changing the temperature of the water going to the taps? I don't see what else you could change.

FWIW, having read the FAQs, I actually think they are talking about controlling heat only boilers with a cylinder, but it is a bit ambiguous.

 

[CBW]

Who has stated it must be opentherm compatible? Which boiler are you considering? Why Does the boiler need to be changed?

 

[MNW67]

Who has stated it must be opentherm compatible? Which boiler are you considering? Why Does the boiler need to be changed?

This is what the FAQs say:

https://helpcenter.netatmo.com/hc/e...-How-does-the-Domestic-Hot-Water-control-work

The Modulating Thermostat can only control the Domestic Hot Water of OpenTherm boilers equipped with a water tank.

Like for the heating, a planning can be created to turn ON or OFF your water heater depending on your needs. You can also check and modify the domestic hot water temperature from the mobile app in the parameters of your Thermostat:

 

[CBW]

This is what the FAQs say:

https://helpcenter.netatmo.com/hc/e...-How-does-the-Domestic-Hot-Water-control-work

It doesn’t offer much information.

 

[Mister Banks]

It doesn’t offer much information.

And what it does say makes no sense!

 

[pajeffery]

Why do you want to control the hot water on a combi boiler with a smart thermostat. Are you just talking about changing the temperature of the water going to the taps? I don't see what else you could change.

FWIW, having read the FAQs, I actually think they are talking about controlling heat only boilers with a cylinder, but it is a bit ambiguous.

You make a good point, I had been talking to the father in law and he had the same problem so ended up looking at solutions.

But, one massive difference is he doesn't have a combi boiler, so he does need to control when hot water comes on. With a combi it doesn't make sense having a schedule as it heats the water on demand.

Can combi boilers be configured to always have hot water on, without buying a separate controller?

 

[pajeffery]

Who has stated it must be opentherm compatible? Which boiler are you considering? Why Does the boiler need to be changed?

Opentherm is from the Netatmo website.
I'm not considering any boiler at the moment, the Netatmo controller would have helped determine that.
Boiler needs to be changed as we're building an extension with ufh and it isn't powerful enough

 

[Mister Banks]

Most would advise against a combi boiler unless you have a small house with only one bathroom. Before you decide on a boiler make sure you have had a heat loss calculation done.

 

[JonathanM]

Boiler needs to be changed as we're building an extension with ufh and it isn't powerful enough

Are you sure? Most combi boilers already have far too much power for the central heating side of things. What power is your current combi?

 

[CBW]

Can combi boilers be configured to always have hot water on, without buying a separate controller?

Not sure about storage combi’s, but a standard combi works on demand, so it’s always ready/on, if that makes sense.

 

[CBW]

Boiler needs to be changed as we're building an extension with ufh and it isn't powerful enough

Ok, what Kw rating is existing and is the extension having hot water demand or just ufh?

 

[pajeffery]

Not sure about storage combi’s, but a standard combi works on demand, so it’s always ready/on, if that makes sense.

Definitely makes sense, at the moment I'm thinking we can just use our existing Netatmo controller, then just have the combi boiler set for hot water all the time instead of on a timer.

The only confusion I have is why there's another controller on the old boiler, I'll check tonight

 

[Mister Banks]

Definitely makes sense, at the moment I'm thinking we can just use our existing Netatmo controller, then just have the combi boiler set for hot water all the time instead of on a timer.

The only confusion I have is why there's another controller on the old boiler, I'll check tonight

A combi boiler doesn't have a timer for hot water otherwise you won't have any hot water when you need it.

 

[pajeffery]

So just had a look at the old boiler, in addition to the Netatmo there is a Drayton Digistat SCR and a Honeywell ST9100S that we had connected, I've never touched them since I moved in.

The Honeywell was wired into the mains and the Digistat, the Digistat was then wired to the 230V terminal in the boiler (Only the Live, Neutral and Earth, 2 other cables were not connected to the boiler).
The Netatmo was wired to the 230V terminal and RT terminal.

I'm guessing that whoever installed the Netatmo decided not to remove the old thermostats, when they should have wired from the mains to the boiler