Vaillant and Honeywell DT99e help

[Dan Masey]

Can't seem to get the stat to control the Vaillant pro24. Have I got this right? The boiler just runs on heating and won't switch off. I then removed the 24v link and it had the opposite effect. Wouldn't switch back on. It's a Honeywell DT90e by the way.

I have a Vaillant mechanical 150 time clock.

 

[Gasmk1]

you have linked the live and switch live which will give permanent live to the boiler, C should be the live back to the boiler

A live B neutral C switch live

 

[quality]

The last photo what the other live going too?

 

[Dan Masey]

So where does the switched live (terminal c) go on the boiler? I thought it only needed 2 core from the boiler to the thermostat?

 

[Gasmk1]

i presume RT is room thermostat so one will be live to thermostat and one will be switch live back you need a live and neutral at the thermostat for the digital display and the the switch live back to the RT if you remove your wires and turn on power to the boiler check the connections on RT one will be 240 one will be 0 the switch live goes to the one which is zero you can at a pinch use your 3 core use live and neutral and use the earth as the switch live but make sure to llabel somehow both ends (eg red or brown insulation tape)

 

[macackau]

Have you removed the link pin on the Pcb? You wire in just a switched live signal in to the purple RT but you must removed the link on the Pcb or it won't work. Second photo where it says RT on the White PCB block that has to be removed.

Vaillant
Remove bridge
Bridge live to A on receiver
Wire B to RT