Gateway for Atag A 285EC and Tado V3+ ?

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Gateway for Atag A 285EC and Tado V3+ ?

Postby Bunzen » Tue Dec 03, 2019 1:40 pm

Hi All,

My new apartement is equiped with a boiler "ATAG A 285EC" (built in 2017, Belgium model) and a wired thermostat "ATAG One". The thermostat is connected on ports 1 and 2 (Atag Z bus) of the boiler, through the ATAG BCU card (Boiler Connection Unit). The boiler also has available ON/OFF connections on ports 3 and 4.

I would like to replace the ATAG One with a Tado V3+ thermostat (to allow Apple HomeKit integration and multizone control with the connected valves).
As far as I understand, the ATAG A Series uses a "proprietary Opentherm" protocol (i.e. the Z-Ready) which may not be (fully) compatible with a "classic Opentherm" Thermostat like the Tado V3+.

Therefore, my question to you is : can I connect the Opentherm Gateway between the boiler ATAG A 285EC and the Thermostat Tado V3+, so both can communicate thanks to the OpenTherm Gateway in the middle?
Will it be fully compatible?

Many thanks in advance for your answers,

Best regards,

B.
Bunzen
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Re: Gateway for Atag A 285EC and Tado V3+ ?

Postby hvxl » Thu Dec 05, 2019 8:53 pm

The OTGW will also require a "classic Opentherm" connection to the boiler. It's not a magic box that can convert different protocols to Opentherm.

However, the equipment matrix shows that someone provided a log file for a different boiler from the Atag A series; the A244EC. So apparently that works with the OTGW. Also other Opentherm thermostat vendors indicate that Atag Z-ready A series boilers produced after april 2009 work with their device. So there's a more than reasonable chance that Tado will work with your boiler, even without an OTGW in between. Possibly the use of the indication Z-Ready instead of Opentherm is a way for Atag to evade the yearly cost of membership of the Opentherm association.

But why don't you ask Tado? That's also what Tado suggests on their support site when you want to know if Tado is compatible with your heating system.
Schelte
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Re: Gateway for Atag A 285EC and Tado V3+ ?

Postby Bunzen » Fri Dec 06, 2019 12:59 pm

Hello,

Thanks for your feedback. I am cross-checking the information from different sources:
- Tado says that their "thermostat V3+" emulates the communication protocol of the Thermostat "ATAG WiZe" so the boiler thinks he is communicating with a ATAG WiZe
- The user manual for the ATAG A 285EC mentions that the boiler is "Z Ready"
- ATAG Customer Service confirms that "ATAG WiZe" is "Z Ready" and we can connect this thermostat directly on ports 1 and 2 of the boiler ATAG A 285EC without any interface.

Therefore, I would conclude that the boiler ATAG A 285EC is fully compatible with the thermostat Tado V3+
However, Tado Customer Service confirms that V3+ is not compatible with the ATAG A 285EC ...

I guess I will have to buy the thermostat V3+ and make the test.
I will keep you posted

Thanks again for your support.

Best regards

B.
Bunzen
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