Cannot fill my closed loop heating system

[mcbod]

I am having a strange problem trying to repressurise my closed loop system.

I believe there is a (small?) underground leak in the system as the pressure regularly drops. Typically takes a few days

So regularly I repressure the loop with a feed valve.
There is a pressure meter near the feed valve so I typically get i just over 1 bar and we are good for a few days again.
Normally, I open the valve, I hear/feel a flow in the feed pipe, I see the meter needle very gradually rise to 1 bar over 20-30 seconds I guess.

But every now and again (e.g. today) it behaves very differently.
I open the value, I hear no flow at all, the meter needle shoots up to about 2 bar immediately, but drops back to 0 as I close the valve. I can't fill it.

I assume it has something to do with air.
I know there is a lot of air in the loop
The rads upstairs near the feed clearly have air in them.
But I cannot bleed them as there appears to be not enough pressure to push the air out

Whats going on?
Whats my next move?

 

[jtsplumbing]

What you need is another person to help, one venting the rads and one operating the filling point, if no one to help take pressure up to 2bar then vent a rad repeat till all rads are full

 

[quality]

Your assumption is not correcto or rather wrong. My personal advise would be to get a decent heating engineer to looks at your problem's because there could be more than one

 

[Old Account]

I’d also suggest to get a qualified engineer as it is not healthy for your system to fill that every 3/4 day’s. As mentioned above perhaps you have got more than just one leak