OpenTherm with no hot water control

MiroPollak

Hello,

I am sorry if this has been answered somewhere, I couldn't find it.

Here is my problem: I have a Brotje WHBS 22D boiler with Tado wireless receiver connected through OpenTherm and controlled by a Tado wireless thermostat (plus 3 more TRVs in the same zone). The heating is working just fine but I can't seem to be able to control the hot water temperature. No matter if I enable or disable the hot water function in Tado (by going to the installer menu on the thermostat), the boiler seems to be controlling the HW temperature itself. For instance, if the hot water function is enabled and I set the temperature to 50 degrees in Tado, the boiler heats it up all the way to 75. As the receiver is connected via OpenTherm, the HW knob on the boiler is disabled and does nothing so I can't control the HW on the boiler if the HW function is disabled in Tado. Also, when the schedule in Tado for HW says it should be OFF, the boiler sometimes fires up and heats the water to 75.

I have already contacted Tado support and they said I should disable the comfort mode on the boiler (my model does not allow that and I don't even think it has that, there is nothing about it in the manual) or wire the thermostat via relay but I don't want to lose the OpenTherm advantages.

Is there any way how I could enable the hot water control directly on the boiler? I am happy to control it that way, I don't need the Tado app for that. I just want to keep the maximum hot water temperature lower at about 50 degrees (the boiler has a function that heats the water to 75 once a week to kill the bacteria).

Thanks for any ideas!

Miro

johnnyp78

Have you asked tado support to set the maximum flow temp to 50 degrees? They can usually do it remotely. Otherwise maybe contact Brotje? There may be something they can do to alter the boiler settings.

MiroPollak

I think Tado is already out of options. I will try to contact Brotje and see what they say.

Thanks!

johnnyp78

I would double check with Tado to make sure - they set my boiler’s max flow temperature without any problem but I had to explain exactly what I wanted.

MichalK

Hi Miro,

I have a similar problem with the Brotje WHBS 22D boiler. But I use a Netatmo modulation thermostat via opentherm protocol. The thermostat does not want to heat my hot water by itself. When I set the water to, for example, 60°C in the app, it saves that temperature and starts heating (if the water is, for example, around 50°C). But as soon as it heats the water to the desired temperature, the setting resets and it's back to 10°C. 

The hot water control switch in the Netatmo app is also unresponsive.  It doesn't matter if the hot water heating is on or off. The HW wheel on the boiler is deactivated and the temperature cannot be adjusted.

I would also appreciate it if the boiler water temperature could be set on the boiler and the thermostat controlled the rest, but it can't.

I'm afraid it must be some sort of Brotje boiler problem.

If you happen to find out any info from Brotje, I'd be happy to post it here.

Thanks Michal.

MiroPollak

Hi Michal,

after some communication with Tado and Brotje, I have switched from OpenTherm connection to 230V relay and everything seems to be working just fine. I can now set the maximum temperature for the heating on the boiler and the desired HW temperature too (also on the boiler). The problem with boiler heating up to a high temperature is gone. As the relay connection does not allow to control the hot water, I have disabled that option in the thermostat.

So far, so good, if it works like this all the time, I am happy.

Best,

Miro

GrayDav4276

Hi @MiroPollak

This does not seem to be the optimal operation of your tado° / combi boiler configuration. Your tado° has been dominating your boilers "comfort mode" and making your boiler heat up your water for when you turn on a tap. Between your boiler manufacturer and tado° you should be able to "disable" the boilers "comfort mode" setting........other combi boiler users have achieved this.