Pairing WIRED thermostats

OldTimer

I've got 2 WIRED thermostats and a wireless receiver. Do I to pair each WIRED thermostat with the receiver?

OldTimer

The reason I'm asking this question is that the CH relay (and Led) on the Wireless Receiver seem to be operating and releasing but not in relation to either of the Wired smart thermostat's demand. I've temporarily bridged the Live and CH NO terminals so that I've got heating. The HW relay and LED work as expected.

Rob

@OldTimer

You only need to pair with the bridge. Later, in the app, you can use the Zone Controller setting to choose for each room (and thus each of your thermostats) individually if they should control the wireless receiver.

Looking at the tado account with the same email address as your forum email address, I see pairing is completed and the zone controller settings are already as they should be. Both rooms in your app should be able to control the wireless receiver. Everything already looks fine, to me. It also seems to be working as it should?

Please do note that with a relay system (as you have) and a heat request that is more than 0% and less than 100%, the relay will rhythmically switch on and off every so many minutes, based on the heat request. So it could be that you see that a room is actively asking for heat (but not with 100%), yet the relay is off. That is normal, assuming it will switch on again within a number of minutes.

OldTimer

Thank you for the comment. There is a problem because l know the thermostat is calling for heating because pump is running and the boiler is heating yet the CH led is not on at the same time.

OldTimer

The reason my heating is working is that as I've bridged the Live to CH NO at the Wireless Receiver so that the wiring center is always powered for heating and therefore whenever a wired thermostat calls for heat it operates the motorized valve, pump, and boiler. If I didn't have the bridge then my heating would only work when the Wireless Receiver relay switches on. Observing it tonight sometimes the relay switches, sometimes it does not, and sometimes it switches off whilst the thermostat is still calling for heat. I don't really want to leave the bridge in place. 😟

policywonk

My understanding of the logic of a normal heating environment is this.

1. All tado thermostats negotiate with the wireless receiver to call for CH heat. There is some trickery in the background to streamline the on-off window, but thats the basic logic.
2. When a Tado thermostat is wired (and that thermostat is wired to a zone valve to switch it on), its logic is, to me, normally expected to work like this - if it is serving as a RELAY:
   1. It sends a message to the wireless receiver to authorise CALL FOR HEAT for CH.
   2. Electricity in its wires triggers its assigned zone valve to open
   3. That valve opens and also relays electrically the POWER ON message
      1. from the wireless receiver,
      2. through the zone valve,
      3. to the boiler and pump.
   4. Thats when the boiler should receive the CALL FOR HEAT request.
3. So, when there are two Tado wired thermostats, each with a zone valve, if neither thermostat believes there is a call for heat,
   1. their wires would not trigger their valves,
   2. their valves would thus have no duty to relay a CALL FOR HEAT request.
   3. the boiler wont fire- because the command must ALSO be relayed through the zone valves.
4. Hence, I find it interesting. For a boiler to be fired by the wireless receiver when neither thermostat has asked for heat through its wires,
   1. Either something has gone wrong with the wiring
   2. or one of the zone valves is bridged in the wrong state
   3. and/or the wireless signals are in disagreement with the wired state signals
5. However if one of those stats did make the connection to its zone valve, and that zone valve completed opening and sent on the power-on message, the boiler would start.

Thats how S plans and Y plans are set up. It is possible to wire it all differently.

So.

How are these stats configured in your app? If the boiler can fire when one thermostat calls for heat, but doesnt fire when the other requests it, the one which seemingly has no impact is either badly configured in the app, or is faulty.

Does that make sense? @wateroakley - have I missed something?

OldTimer

My problem is that the Wireless Receiver CH relay is either not switching on when a thermostat demands heat or sometimes switching off before the thermostat ends it demand for heat.

I noticed this issue during testing on the workbench so I bridged the Live to CH NO on the Receiver during installation so that heating would work.

In my system the 2 Wired Thermostats are wired into the S plan wiring center and both thermostats have the same zone controller in the App. In the wiring center each thermostat activates the appropriate zone valve which when open fires the boiler and pump. I can see that when either thermostat calls for heat (observed by the fact that the thermostat has activated a zone valve) the CH led on the Wireless Receiver may or may not be ON.

Since both thermostats use the same zone controller is possible that there is an interaction between them e.g. both thermostats call for heat at the same time and then when one thermostat switches off, the receiver switches off the CH relay even though the other thermostat is still calling for heat?

The HW channel works as it should i.e. the HW relay is on when HW is on and the relay is off when HW is off (there's sometimes a delay of a few seconds when a change of state is commanded).

policywonk

Have you contacted Tado through the app to ask for a replacement receiver? Looks like you have one faulty component - ie the wireless receiver isnt doing its job.

OldTimer

I've noticed the problem 3 times today (10/11/24), at around 8.10am, 9.00am and 13.57pm. Is there anyone who can look at the message flow for these times. In all cases the upstairs stat is calling for heat but the Wireless Receiver has not operated the CH channel.

policywonk

@Rob Would you pick up on this again please?

OldTimer

I'm beginning to think the problem with the Wireless Receiver's CH relay is caused by delay between the various signals involved. There is always a delay between seeing the thermostat calling for heat at the wiring center (which has an indictor light for each thermostat) and the CH relay switching. Sometimes this a second or so but sometimes longer. Does anyone know the message sequence between the thermostat/server/wireless receiver ?

policywonk

@OldTimer have you contacted Tado through the app and pressed for support?
1. If you force the wireless receiver to fire the boiler does it ( even up to a min later)?
2. If that works, even if two wired thermostats are not together asking for heat, but only one is, don't worry, there isn't an electrical contradiction. It should force the motorised valve open. However if the valve doesn't open when one of the stats says "go" then have you considered if the valve is the problem?
@Rob Got a moment?

OldTimer

1. The wireless receiver does not fire the boiler, it only supplies power to the wiring center. The wired thermostats are connected into the wiring center.
2. Each thermostat closes a circuit which lights a lamp (so I can see which thermostat is calling for heat) and operates one of 2 motorized valves. When the valve is open the boiler gets fired.
3. So when a thermostat calls for heat there is an immediate indication irrespective of the valve.
4. Due to the link at the wireless receiver the wiring center is always powered regardless of the CH relay in the receiver. My observation is that the CH relay is not always in tune with the state of the thermostats. At about 21.21 on 23/11/24 a thermostat switched on for about 2-3mins and switched off without the CH relay operating.
5. Without the lamps in the wiring center I probably would never of noticed this, but there is definitely a delay in the CH relay changing state. A few seconds is not a problem but sometimes it is much longer.
6. I have not called support since my view is that the wireless receiver itself is not at fault but the observations may be due to message delay or loss. We need a trace of the messages.

policywonk

IIRC, when a stat triggers, over radio waves it informs the wireless centre, and over its wires it triggers the motorised valves. This means that both the stats and the wireless centre must agree to the call for heat. That however isnt enough.

The motorised valves must then complete their opening process to relay the call for heat, via the wiring centre to the boiler. If their microswitch is burned out - just had two of them go at the charity buildings this week - they dont pass on the request for heat. Had to replace the head units.

As you seem to be comfy doing electrical tests would you force the stat to open the valve and then check to see whether the switched live is transferred to the boiler's call for heat? Do it on both valves? If both are fine, time to push Support hard for a response. They seem to take about 2 weeks to act.