How to go about preventing a total system failure?

Floob

Before I had my new combi boiler and Tado installed I had an older system with a separate water tank. If that old boiler ever had issues I could simply use the condenser heater in the water tank and still have hot water.

Now that my new boiler has Tado connected, as far as I can see I cant even force the boiler back to manual mode if I needed to (it seems to need to be 'commissioned' by a plumber). If Tado/Boiler comms breakdown it looks like it could be a major issue.

So my question is really, in order to pre-empt an issue with the boiler being connected to Tado and no heating requests getting sent to the SRVs or hot water firing, what is my best bet?

I'm thinking I should buy a spare Tado wireless receiver and bridge, and the moment the boiler/tado stop talking to each other, call the plumber and give them the spare unit, or get them to set it to manual operation so it will actually provide hot water/heating?

Rob2

My system uses a modern OpenTherm bus and so I can just disconnect the Tado and connect an existing (Honeywell) OpenTherm thermostat to control everything.

But it seems that such installations are rare in the UK and everyone still uses relay control? Then it could be a bit more difficult as there is more than once circuit to connect.

Floob

The setup with the Vitodens 100-W uses openthem, but I've got no idea about how to just re-wire a new (Tado receiver) one in.

I'm looking to make the whole process as easy as possible for the plumbers I'll be calling. So I was thinking to buy a spare receiver unit.

Failing that, I'm assuming (if its the tado unit failed) the plumbers can quickly re-commission it in manual mode.

Andreplusplus

What exactly is your fear? Is your tado connected via a wire to the boiler? Or is it wireless and do you have a wireless receiver connected to the boiler?
Do you fear internet outages? Because you don't need internet- you can always manually control the tado device.

hugbilly

Mmm, control of the system without internet is pretty limited. . .

Floob

@andre75 My fear is the Tado receiver attached to the boiler fails and the boiler is stuck in Opentherm mode and cant be set to manual mode without changing the commissioning mode

Andreplusplus

I read that as "leave it to the controller in those modes". But if tado thermostat fails I cannot believe you are not able to switch your boiler on and off to heat your home.
You can test of course, by removing thermostat and replace by another controller, or if you don't have one, connect the two wires, which should fire up your boiler.

Floob

Yes, I'd like to test that, but at the moment the Tado receiver is powered via the boiler, so I cant switch it off without switching the boiler off. Maybe its a better approach to power the Opentherm controller independently?

Viessmann have said:

"The change has to be done from the Commissioning screen, option C7:14 to C7:1 then go to last setting in list until END shows then confirm with OK."

But I cant see how to do that as a user - so I've gone back to them.

Floob

Tado have just said:

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"If there is a hardware fault and tado is still under warranty we would replace it if we consider it necessary after checking the invoice of purchase for warranty purposes.

For you to get the heating while the hardware is faulty, we can provide you with instructions to bypass the system to make the heating work.

The C.7 is only a setting that the boiler needs to either work with Opentherm or Relay, but for you to get emergency heating, you would need to either install your system as it was originally, or use our bypass instructions."

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So maybe there is a way to get the boiler to ignore the attached Tado receiver without it being re-commissioned to "Manual" mode.

The C7 modes are

Andreplusplus

“Yes, I'd like to test that, but at the moment the Tado receiver is powered via the boiler, so I cant switch it off without switching the boiler off. Maybe its a better approach to power the Opentherm controller independently?”

—> can’t you just disconnect the control wires (+/-) from the receiver to test?

Then disconnect the wires - boiler off. Connect wires - boiler on.

Floob

Ok, so Viessman have said:

"The change has to be done from the Commissioning screen, option C7:14 to C7:1 then go to last setting in list until END shows then confirm with OK. The Commissioning Screen is where the Installer set up the Boiler functions, this is in the Installation and Service Manual that the Contractor had on receipt of the Boiler, there are other settings in there that, if changed by mistake, could put the boiler into a fault state, so in theory, this should only be done by a competent Person, i.e the Installer or a Heating Contractor."

So if I wanted the boiler to change to manual, I need a plumber.

Tado have said, to avoid that:

"So the only thing you need to do is turn off the power and then open the tado receiver front cover. Connect both +/- wires together by for example connecting them in one slot (example: connecting both +/- wires in connection + so that they are both together). This will make your heating come on permanently and you will then need to turn the boiler off when the heating is no longer needed."

@Andreplusplus That sounds like the sort of thing you are suggesting.

So it sounds like if the Tado receiver breaks, I should do that. But to be honest I dont want to play about with wires, so either way I think I'll just call the plumber asap to sort it. It still sounds like to me, if I wanted Tado up and running after a hardware failure I should have a spare receiver handy.

Rob2

When you don't want to play with wires you could ask the plumber to install a switch (near the Tado thermostat or near the boiler, whatever is convenient) that connects the two wires yes/no as desired.

Floob

Thats a good point, thanks. I'll look into that.