Atag One replacement

[brewmook]

Hi,

I have an Atag iC Economiser 27 boiler from 2017, not the more recent "plus" model. It came with an Atag One controller which is hooked in with a 2 wire OpenTherm bus connection.

The controller is about to pack in and I'm looking at Tado instead. The controller battery is on its last legs and a new one from Atag will be 90-odd quid!

In general, has anyone had any issues with OpenTherm compatibility with this boiler?

More specifically, I've been looking at Tado as a replacement. I've read that the only UK model that does OpenTherm is the wired thermostat. Is that really the case? Looks to me like the "Wireless Receiver" in the wireless kits have OpenTherm too.

Tado support said I'd need the "One BCU" module for this to work. I'm interested in the details of what that is and why it's needed, but I didn't want to bug a clearly busy Tado support person. Can anyone elaborate?

Atag themselves are touting Tado on their website, so clearly something works, maybe just not this model. Their support folk aren't too willing to discuss these kind of details with non-accredited installers. I'm keen to keep the 14 year guarantee alive, and tado is "blessed" by Atag.

Why won't the OpenTherm bus connection "just work", regardless of controller manufacturer?

Can I just use the basic on/off connector? Is modulation of the boiler via opentherm really that big a deal?

Thanks,
Dave

 

[king of pipes]

I have the same boiler and swapped out the One controller for a 3rd generation Nest stat I've not had a issue since and it works fine with open therm , I can't advise on Tado but reading the literature I think it's suitable opentherm will definitely improve your energy efficiency and save you money on your gas bill. Kop

 

[Scott_D]

I thought the 14 year guarantee was a recent thing?

 

[brewmook]

I thought the 14 year guarantee was a recent thing?

I'm pretty sure they were on about extending the warranty to 14 years when I got it in 2017. Could be wrong.

 

[Scott_D]

Your paperwork should state the warranty you have.
I also believe you need the ATAG filter, scale reducer and controls to extend the warranty. (Same as most manufacturers)

 

[Knappers]

I think good optimisation with opentherm is under-rated.
Literature I've seen states 1-2% saving but I'm sure these are like for like comparisons.
I think with added comfort of a well setup load compensated ststem, heating can be run at a lower temp for same comfort level.
If that's possible then should be more like 10%

 

[king of pipes]

I think good optimisation with opentherm is under-rated.
Literature I've seen states 1-2% saving but I'm sure these are like for like comparisons.
I think with added comfort of a well setup load compensated ststem, heating can be run at a lower temp for same comfort level.
If that's possible then should be more like 10%

I totally agree the hardest part is educating people that their radiators don't need to be piping hot all the time . Kop

 

[brewmook]

Thanks for the replies.

I eventually got a reply from Atag. They didn't outright say I need the BCU, just to "follow Tado Technical Support".

Tado came back again with "Your current system is working via the ATAG EBUS, but tado° must use OpenTherm. And for this boiler to use OpenTherm, the BCU or translation module needs to be there." Clearly that's not entirely true if Nest works fine.

So inconclusive whether Tado will "just work".

Lost my paperwork, but I'm only on the 10 year warranty after all, apparently. Opting for a second hand Nest E from Gumtree in the end. So cheap it won't matter if it doesn't work.

Cheers,
Dave

 

[king of pipes]

Thanks for the replies.

I eventually got a reply from Atag. They didn't outright say I need the BCU, just to "follow Tado Technical Support".

Tado came back again with "Your current system is working via the ATAG EBUS, but tado° must use OpenTherm. And for this boiler to use OpenTherm, the BCU or translation module needs to be there." Clearly that's not entirely true if Nest works fine.

So inconclusive whether Tado will "just work".

Lost my paperwork, but I'm only on the 10 year warranty after all, apparently. Opting for a second hand Nest E from Gumtree in the end. So cheap it won't matter if it doesn't work.

Cheers,
Dave

I don't think that's entirely true but as I said before Nest is compatible. Kop

 

[PaoloTherm]

Hi everyone,

I have purchased a Nest 3rd Learning for my ATAG I28C (I-Serie 2016 year) and it works pretty well.
Unfortunally modulation is not perfect like weather compensation mode (without ambient controller, only external temperature probe connected to the boiler).
I bought the Nest for a smarter and tighter heating managment but when ambient temperature reach the set-point, Nest turns off the boiler.
Furthermore I must strictly set the maximium heating water temperature , because it seems that sometimes Nest raise up the water temperature to the maximum value.
At this point I would ask to King of Pipes, if he has the ATAG BCU (of One kit) between ATAG boiler and Nest Heat Link (I suppose that you have the same model of me - 3rd Learning).
TY
Paolo

 

[brewmook]

The Nest E is working, but I'd agree the modulation is quite "different". I've not had it in long enough to really get a good impression yet.

I really miss being able to see the set point and flow/return temp from the app. I'd like to explore the API some day, though probably I'll never have time.

 

[king of pipes]

Hi everyone,

I have purchased a Nest 3rd Learning for my ATAG I28C (I-Serie 2016 year) and it works pretty well.
Unfortunally modulation is not perfect like weather compensation mode (without ambient controller, only external temperature probe connected to the boiler).
I bought the Nest for a smarter and tighter heating managment but when ambient temperature reach the set-point, Nest turns off the boiler.
Furthermore I must strictly set the maximium heating water temperature , because it seems that sometimes Nest raise up the water temperature to the maximum value.
At this point I would ask to King of Pipes, if he has the ATAG BCU (of One kit) between ATAG boiler and Nest Heat Link (I suppose that you have the same model of me - 3rd Learning).
TY
Paolo

No I don't have the module fitted just 3rd generation Nest and heatlink wired to opentherm connections in the boiler Atag ic27 economiser . Kop

 

[PaoloTherm]

No I don't have the module fitted just 3rd generation Nest and heatlink wired to opentherm connections in the boiler Atag ic27 economiser . Kop

Ok, and do you observe the effect of modulation? In my case, the boiler works at the maximum temperature value that I have set on the thermostat and on the boiler panel. Obviously i've also setted Opentherm mode into the settings menù of the Nest, but it doesn't matter: when set point ambient temperature is reached, the boiler turns off (for the joy of the reporting section! -_-"").

 

[PaoloTherm]

and then... and then in a GERMAN boiler manual you find that "The following (clock) thermostats can be connected to the ATAG i-Series:

• Bus: connect the ATAG One directly to the BUS position.
• Bus+OT-LPA1): connect a Round Modulation, WiZe or OpenTherm thermostat/controller on OT-LPA (1) and then on OT-LPA in position

BUS (2). See figure 9.1.a.

1) OT-LPA stands for OpenTherm Low Power Adapter.
This adapter must be between the autopilot and
thermostat/regulator be connected, if
there is an ATAG WiZe, Round Modulation or other OpenTherm controller is used".

OT-Adapter is a ridiculous little circuit to be applied in series between the cable coming from Opentherm interface (Nest Heatlink in this case) and the boiler control board. Maybe I'll try it, but I have to find it before.
Meanwhile, I'm speechless, I just say DAMN!

Why informations are soooo fragmented?! --..--