Hot water via the programmer doesn't ignite the boiler

[MadaCup]

I've had Tado running over the past week with mixed results. The main issue was that when the scheduled water came on so did the heating. Not ideal when it's as warm as it is at the moment. Tado support (and various sources on the internet) suggested the 3 port mechanical valve, a common problem is the motor going so it cannot open/close the valve to direct the water. I have only owned the house for 6 months and the previous owners didn't look after it, the switch on the 3 port valve was set to manual rather than auto.

I ran out and replaced the motor in the mechanical part of the valve, hoped that would be the end of it. Not so.

Now (and periodically before using Tado) I cannot switch the hot water on. I have even put the old honeywell thermostat and programmer back on but it behaves exactly the same. When I put the hot water on continuous nothing happens at the boiler, yet if I switch the heating on continuous it fires up he boiler straight away.

I have tried the switch both on manual and auto and nothing seems to change it.

Any thoughts?

The 3 port motorised valve looks like this: http://www.honeywelluk.com/products.../V4073A-Motorised-Midposition-Diverter-Valve/

 

[MadaCup]

Ok a strange twist. I followed the instructions I found online and in the checkout guide it suggested cranking up the thermostat on the boiler to maximum, then turning the water on continuous. The boiler fired up straight away. I have put the boiler thermostat back to the suggested 60 degrees and it won't turn on again.

Thinking about it my son hasn't had a bath and we haven't used the shower tonight nor used any other water for washing up etc. Could the boiler be at 60 degrees hence why it doesn't need to come on any further?

 

[MadaCup]

I think my theory last night may have been correct regarding the water having not been used at all yesterday so therefore the hot water didn't need to actually be on.

I had a 10 minute shower this morning and the hot water switched on straight away after plus the heating didn't come on at the same time. If my theory is right, I have wasted hours on this yesterday!

 

[D_Hailsham]

If my theory is right, I have wasted hours on this yesterday!

Not all wasted. You have, hopefully, learned that the boiler temperature needs to be higher than the cylinder water temperature, otherwise the boiler will not light.

 

[MadaCup]

Thanks for the confirmation, really helpful.

Looks like I fixed the 3 way valve so I think that's a decent result.