Gas boiler not heating the immersion tank

Our four-year-old Potterton gas boiler has just stopped heating the hot water tank (the central heating is still working fine, thankfully).

All the pipes into the tank are cold, and I've tried setting the thermostat on the tank hotter and colder, to no avail.

Any suggestions on what else I can try to locate the problem? And would this be a job for a plumber, or someone who services gas boilers?

Thanks for the help as always

Motorised valve is faulty, you can manually open it if you know where it is, it is a box on a valve on a pipe, probably near the cylinder. It will have an electrical cable coming from it.

A plumber can change it for you.

Many thanks Davy for that prompt analysis, glad it's not the boiler

S.

if you can find the motorised valve it is quite easy to open manually.