No hot water for 2 days, help!

[Missb00]

Plumber keeps letting us down. No hot water, no emersion either. Heating and cold water are fine. We have a Nest system installed and this seems to be working ok, don't think it's causing the issue as heating it working ok. Have reset boiler a few times and no luck, any ideas what could be causing it??

Can it be something stupid like water pressure?

Just to be clear, the water from the hot tap is cold or there is no water from the hot tap?
Assuming the water is flowing, and assuming it's a conventional boiler with a hot water cylinder not a combi (as you mention an emersion) I would assume that it's either the Nest or possibly the two/three port vavle to the heating coil in the cylinder. The latter would not effect the immersion so it's either a second issue or something common (ie the nest if it controls that as well. Most two/three port valves have a position indicator and/or override leaver, can you checknow that the valve motors to the correct position? If not it could be the valve or the controller, if you can operate the valve manually this will give you hot water until late you identify the problem (though rads and tank will run together). Hope that helps.

do you have a hot water cylinder?

What colour?

Post several photos of it, and the pipes, other equipment, and cables around it. if you have an immersion heater in the cylinder, photograph its cap, and show where the cable goes.

Cold water is coming from the hot taps. Thank you I will get all the pics and post them in a while!