Heating Problems

I know it is the fourth pipe - as a smaller pipe feeds out of this and this must be the feed into boiler.

I have a jpg showing the pipes - but not sure how to attach it here...

So you are saying I cannot re pressure the boiler myself - I will need a need a pump with a schrader valve and a pressure gauge ? Thanks

New members aren't allowed post images.

With the pressure that low, there's a chance you have a problem with the pressure vessel. You'll need a pump with a gauge to check and repressurise as required.

The valve feeding the heating system shouldn't be left open.