Changing the boiler maximal temperature, opentherm connection

ai1

Hi,

I am using tado V3+ wireless kit with my Chappee Sempra Nova HTE (aka Remeha, De Dietrich, etc) over Opentherm connection. Surprisingly, it works, although Tado support says that the boiler is not supported and Chappee support says that the boiler does not support Opentherm.

Meanwhile, I would like to set the maximal temperature of the boiler, because when Tado calls for heat the boiler goes up to 90C. Is it possible to modify the maximal temperature? Could I set other parameters using Tado thermostat or application?

Thanks in advance,

Anatoli

johnnyp78

You can change the max flow temp yourself now, though there might be an issue if both Tado and the boiler company are saying Opentherm isn’t supported. Are you sure it isn’t using ebus?

If it’s opentherm you can set the max flow temp here https://community.tado.com/en-gb/discussion/8611/release-opentherm-max-flow-temperature-setting

ai1

Great. Many thanks. Will try and report later today.

A priori, the protocol does not seem to be ebus--the only brand of the group using ebus seems to be Valliant. The original controlling thermostat--this one

https://geoplanete.fr/2374-sonde-d-ambiance-filaire-programmable-sempra-nova-hte.html

--has a choose among possible Opentherm parameters (set to auto). In fact, the boiler (week 26 of 2017) is claimed to work with Chappee proprietary R-bus interface, which is clearly does not (tried that at lengths).

I was also wondering if, say, max temperature setting is reset each time the thermostat calls for heat, or it does not change once set.

ai1

I was also wondering if, say, max temperature setting is reset each time the thermostat calls for heat, or it does not change once set.

Sorry, I meant that once teh setting is sent to the boiler, it is saved to boiler memory and is not reset by the thermostat each time it calls for heat. Thanks again

johnnyp78

Once the boiler has been told the parameter, it should keep it. You can check what it is in the Tado pro app.

ai1

Hi again,

it works. When using "tado for installers" application, I can see the correct boiler temp. When I modify the the max flow temperature, it also seems to work, but I will check this using the original chappee thermostat.

Finally, I believe, although denied by Tado and Chappee supports, Opentherm is functioning with my boiler--Chappee Sempra Nova HTE. The tricky point may be the exact production date: week 26 of 2017. It seems that starting from November 2017 the boiler use R-bus interface, in which case there should be a big R-bus logo on the boiler sticker.