No filling loop and red expansion vessel installed. How to represurrize heating?

[Riley]

 

[samsg30]

Looks like system is piped up in a way that will be hard to fill and be prone to air locks. No way to bled air from boiler return except on the compression joint. Feed and vent positions look wrong before pump but hard to see. I would repipe it or turn into a sealed system. I think you will keep getting problems as it is

There's a drain valve on the bypass circuit (with red valve set on 0,4 bar). Is that where it should be and to be used to remove air lock? Else there are two radiators on ground floor where similar drain valve is present. I used one of them to drain the system and not other.

 

[samsg30]

I'm going to say it's your pump.
You said you've got f.22 error on a glowworm that's not low water pressure (that's f9) f.22 I believe without checking is low flow rate through boiler/boiler flow return temp differential wrong
I would start with the pump.

Edit just checked, f22 is described as low water pressure but that doesnt really apply to this boiler with your setup

Yep.. and that's the reason for this whole conversation that there was no filling loop to increase pressure. But now I know as this is open vented system, no need for pressure loop and pump is on the highest point already. F22 disappeared after resetting boiler twice, but many radiators were not getting hot.
Plumber advised to close TRV on radiators which are getting hot so water is pushed to other rads, which did a trick but still there are two rads (one on ground floor and other is towel rail where inhibitor was poured in) which are not getting hot at all and upon bleeding, cold water is coming out.

Not sure if there is air lock in the pipe as such which need to be vented out and how?

 

[Alex Knight]

What do you mean pump is on the highest point?
I've had plenty of pumps that run okay but are sludged up so they are not pushing water round as much as they should, only way of telling is by removing the pump head.

You can try shutting all the rads off apart from the two that don't work that should force any air out, I find flicking the pump between speeds quite often clears airlocks too, also check that the lockshield side of the radiator is open on the two that don't work