Tap Water/Central Heating Question

[sist_si]

Hi guys,
I got up this morning to take a shower and there was very little water coming out of the taps even when I was opening them up quite a lot. This was fine yesterday so I'm not sure what's going on.
The water heated up ok but just had no power. I checked the boiler and it was on and the pressure was just below 1 bar (or the correct marker on the guage anyway).
Now, the boiler does have a slight leak which an engineer has looked at and said it's the 'flow valve' I think and that it should be relativley easy to fix. This has been like that for a few weeks though and it's not caused this problem before.
Anyone got any ideas??
Anyone know any reliable plumbers in Birmingham?

 

[UKDTweak]

The pressure is below 1 bar ?... in my house its between 2 and 3?? Was the same in my last house too, perhaps you need a little more. Ignore th marker, if it anything like mine, you can move the marker to were you want it.

 

[sist_si]

I *might* be wrong on that 1 bar thing....basically, there is a dial guage on the front of the boiler and it has a green segment for the needle to sit in. At the moment, the needle is sitting just below the green area. I can easily refil to top that up as I've done that before. Just never had this lack of water before!?!