Flexible metal pipe

[brenton]

The heating is not working at all. The hot water works but goes very cold after a short time. There's a little button inside the boiler that I press and can sometimes gain a little more hot water. It's a combi boiler

I know there's a flexible metal pipe that you can connect to the two bottom connections on the boiler but I'm unsure as to how this actually works to sort out the pressure.

 

[ArtfulBodger]

It's very unlikely that you need to re-pressurise the system via the filling loop - if there wasn't enough pressure it just wouldn't start at all.

Your system is overheating and tripping the thermal cutout. You really need to get an engineer in to work out why.