Heating engineer help please

[NextSlidePlease]

Morning all, im in a bit of a pickle.

In short i fit a bathroom for a customer and now his hot water wont turn off.

The programmer is set to off yet the boiler constantly fills the hot tank. Have to turn the power off at the wall to get it to stop. Any ideas what could be causing it?

All i touched was to close the header tank gate valve, drain the central heating loop to install a towel rail and open the valve to fill it back up again.

Oh and install a shower pump. So power was turned off for a few hours.

Vented systems are a bit of an unknown for me so can any engineers out there suggest a few things to try get it running again?

Here are pictures of the setup.







The photo i took of the pump is really blurry but its a grundfos ups3 which is constantly running no matter what we do to the programmer. There is another white box above the pump with a button on it, perhaps a wireless receiver for the programmer i dunno.

Thanks in advance for any suggestions. Customer seems to think its a bit coincidental that its happened but i cant for the life of me see what ive altered to make it suddenly break like this

Edited by NextSlidePlease on Wednesday 30th April 09:52

[mikewps24]

Sounds like an issue with the motorised valve. Did you pin it open when draining the system and not release it afterwards? If the programmer is set to HW off and is not faulty then the only thing that could be firing the boiler is the motorised valve.

[andy43]

I'd guess at the valve too, but if it's not been manually locked open/closed...
Power goes from the timer, to cylinder stat, to zone valve to open it, then power goes from the zone valve 'OPEN' signal on it's relay switch once it's powered open and on to the boiler to call for heat.
If you can test for voltage at those points or at a wiring centre you may be able to work out what's sending the volts to the boiler.
Could be a stuck relay in the boiler or timer too.