Hot water does not turn on after bleeding radiators

edited December 2022 in General Questions & Topics
Everything was working fine until I bled my radiators, which reduced my pressure and I had to call a gas boiler engineer. Now we are baffled because CH system works as normal via tado but hot water does not even fire the boiler . To turn on hot water , I have to turn the CH on, then change my 3 port valve in the manual mode which allows the hot water into my cylinder. I have to wait for the entire 400litre cylinder to be hot until the hot water flows out....around an hour or so. I am wasting so much of energy and costing me ££. Why can't tado just be simple. We did not touch or change any wiring, the engineer only came and flushed the system. We also replaced the hot water valve which he thought might be faulty. The extension hit is connected to a Honeywell system and I have a Potterton Gold HE combi boiler.
But the irony is ....the hot water light comes on but does not fire the boiler at all, not does it open up the valve when the hot water is on. Central heating works just fine. We have Honeywell wiring and a Y plan.


  • Sounds like it’s either the valve itself sticking or your engineer incorrectly wired the Tado to it when he replaced the old one.
  • I agree with @johnnyp78. If the HW LED is illuminating then it proves the App and communication between Tado devices is working. The HW NO terminal will switch from 0 to 230V to activate the valve. Did the heating engineer check this? With a volt meter it's very easy to prove if Tado is actually switching on the HW circuit.
  • Yes , he did check the connection is going from EK to HW circuit. We had made no changes to the wiring after bleeding the valves and changing the leaking cold water bypass connector pipe. The HW led turns On in the tado but it seems it does not send any signal to the HW unit.
  • The engineer opened the HW box and reconnected the same wiring again but no luck. The hot water signal doesn't seem to turn the boiler on at all, let all the valve. Is there any other hot water thermostat or other reset that can be done? May I reconfirm, if I start the boiler via CH and manually open the HW 3 port valve, the hote water rushes into the hot water tank and we are currently using that hot water but it is consuming too much energy
  • I think you’re going to need to contact Tado support. What device is actually installed? The extension kit doesn’t have a hot water led.