New WIFI thermostat controller not connecting to heating boiler. Help me connect the wires

penzdar

Hi everyone,
The situation:
I have one of those normal round rotary thermostat controller for my Bosch 30 HRC boiler. Here is the manual from the boiler (I only found it in Dutch):
https://www.libble.eu/bosch-26-hrc/online-manual-3313/
I purchased a WIFI thermostat controller for it, so I can modernize it and to be able to control and schedule the heating.
Here is the WIFI controller:
https://www.aliexpress.com/item/1005005989585435.html?spm=a2g0o.order_list.order_list_main.17.6edc1802gW3wxv
Basically, you connect a receiver to the boiler and mount it on the wall. The receiver remotely receives the prompt from the mobile controller device which can connect to WIFI. So the receiver should be stationary and directly connected to the boiler.

The problem:
While trying to connect the wires, I read the user manual from the controller saying I need to connect the two wires "OPEN" and "COM" to the boiler. As seen in the manual picture


The boiler, however, does not have OPEN and COM. It instead has connections marked with O,T,F, and A. The wires from the rotary controller are connected to O and T.

I tried connecting OPEN to O or T, and COM to O or T, it did not work. I even tried the other controller method with the 1,2,4,7,8,9 connections. It did not work either.
The manual says, when I click the button inside of the receiver, there should be a flashing green light visible, which allows me to start the pairing process with the mobile controller. But it seem like the receiver is not getting the right signal. Also, after 1 minute, the boiler shows an error indicating that there is no controller connected.
I tried everything, can you please help me connect the right wire to the right place?
Should I power the receiver maybe? The manual says the power is only needed for electric powered floor heating. So I did not try that yet.

Jamie Hall

"open" and "com" should work in exactly the same way as the nice simple round thermostat's two wires. Wherever they were connected on the boiler would be where you would connect them -- and it shouldn't matter which wire goes to which.

However.

That assumes that your wifi controller sends the heat signal to the internal relay which has the 'open" and "com" terminals.

Do you get the flashing green light in the receiver?

And going back a step here... does the boiler work properly with the old thermostat?

penzdar

Thanks @Jamie Hall for your comment
I did connect them the way you are saying. The flashing light did not appear. And yes, the old controller does work. So, I wonder why the receiver is not recognized.

Jamie Hall

Does the receiver have power (I know, silly question...). It will require some kind of power to operate at all...

penzdar

@Jamie Hall I was thinking the same. See the photo from manual. There is the possibilith to connect power. But it seems that its needed only for when you wanna connect floor heating powered by electricity. Should i connect city power to L and N?

Jamie Hall

Without some power it's not going to work. It's not magic. L and N usually are for 120 volt AC, but I have a feeling you may not be in North America? In which case, check the manual and the specifications to make sure that you grid mains are supplying what it wants.

EdTheHeaterMan

This diagram in the Installation Instructions shows that power must be provided to the unit that you place near the boiler at 5 and 6. The 4 and 7 are what is optional for electric heat

penzdar

Ok. So here is a happy follow up. The unit indeed required city power. The instruction was somehow vague. In one picture online it mentions the need for power and in the printed instructions it mentions not. Also bad translation (i assume ftom Chinese) "zero line" meaning N and "fire line" meaning L.
Anyways. After the unit was powered on, I tried to connect it to the same connections as the old controller (OFTA). And it did not work. So I tried the second method provided by the Bosch instructions. Which is simply an on and off trigger flr the flame. Now its all working nicely. I just feel like the flame is on more often compared to when the controller was connected to OTFA unit. Perhaps flame trigger's timing is less smart?
It remains to be monitorred . Thank you all for your help.