central heating vaillant boiler

akira181

That green tank is an open vented hot water cylinder.  The system boiler heats the water within and stores it until required, it's not used for central heating.  The pump on the floor looks like a booster pump for the shower to get better water pressure.  The red pump is for central heating, which is a closed circuit, separate to the one for hot water from the taps.

The boiler not staying on could be one of a number of things and isn't really a DIY job, especially if you don't know how it works.  Safest thing to do is to get a heating engineer out to troubleshoot and he can also explain how your setup works.

tetrarch

Is the (red) circulation pump working properly?

These often jam up, the good news is that they are easily freed by removing the screw on the side and manually forcing the valve to turn with a flat-head screwdriver (Do this with the power to the pump OFF)

Regards

Tet

It might 

aggi

Thanks again, got someone coming on Wednesday, will let you know how I get on. The red pump is very hot to touch so wouldn’t be surprised if turns out faulty.