Heating Wiring Problem - cylinder thermostat not working

[dfreitag]

By the way this is the manual I found online..

https://www.vaillant.co.uk/downloads/z/ecotec/ecotec-installation-servicing-2-2005-261445.pdf

 

[dfreitag]

And sorry, I forgot to reply.

It was working just fine until I decided to have a Nest Thermostat installed, and it was downhill from there..

It seemed to be working fine for a while, but maybe I just didn't notice the boiler running & overheating constantly at first..

 

[Aaron b]

sure - do you mean the boiler label (below)?

I WAS TOLD THIS PCB IS NEW!! I paid £250 for it... did the guy rip me off bringing me a used one??

View attachment 100150

I just loaded a manual from Google instead of their website and it looks more like yours. It appears that it doesn't accept any switched live but expects a switched signal between 3 and 4. The orange and grey cores are the switched ones from the valves and could be used for that.

Do you have a meter to test that there is 230v on terminal 4?

 

[dfreitag]

I just loaded a manual from Google instead of their website and it looks more like yours. It appears that it doesn't accept any switched live but expects a switched signal between 3 and 4. The orange and grey cores are the switched ones from the valves and could be used for that.

Do you have a meter to test that there is 230v on terminal 4?

Ok, I see..

I don't have a meter at the moment, but can go buy one if it will help!

 

[dfreitag]

one like this?

Digital Multimeter Car Battery Circuit Multi Tester Voltmeter Ammeter OHM AC/DC Voltage DC Current Continuity Resistance Diodes Transistor Electrical Test Meter with Test Leads Backlight LCD : Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop Digital Multimeter Car Battery Circuit Multi Tester Voltmeter Ammeter OHM AC/DC Voltage DC Current Continuity Resistance Diodes Transistor Electrical Test Meter with Test Leads Backlight LCD.

www.amazon.co.uk

 

[diditrain]

sure - do you mean the boiler label (below)?

I WAS TOLD THIS PCB IS NEW!! I paid £250 for it... did the guy rip me off bringing me a used one??

View attachment 100150

The white flex appears to be connected in all the right places, albeit sub-standardly.
I would turn the heating and hot water to the off position and then check to see if there is any voltage between neutral and the grey wire. The boiler and pump should only fire up when there is a demand for either heating or hot water or frost protection situation, which is highly unlikely at the moment, due to all the glorious sunshine.

 

[diditrain]

sure - do you mean the boiler label (below)?

I WAS TOLD THIS PCB IS NEW!! I paid £250 for it... did the guy rip me off bringing me a used one??

View attachment 100150

Also the pump usually runs on for a few minutes after the demand for heating or hot water has ceased, in order to take the excess heat away from the boile.

 

[dfreitag]

OK, just bought a meter.

V~ 200 and on 4 and 3?

I just loaded a manual from Google instead of their website and it looks more like yours. It appears that it doesn't accept any switched live but expects a switched signal between 3 and 4. The orange and grey cores are the switched ones from the valves and could be used for that.

Do you have a meter to test that there is 230v on terminal 4?

 

[dfreitag]

The white flex appears to be connected in all the right places, albeit sub-standardly.
I would turn the heating and hot water to the off position and then check to see if there is any voltage between neutral and the grey wire. The boiler and pump should only fire up when there is a demand for either heating or hot water or frost protection situation, which is highly unlikely at the moment, due to all the glorious sunshine.

Hi, thanks

ok, so on the meter V~ 200 and on the blue (N) and grey wire (4) on the PCB?

Thank you

 

[dfreitag]

Right. So measured between the blue (N) and grey wire (4) on the PCB - and it's always 244V

No matter if the boiler is running or not.