how to open combi release value/drain system

[chucklepie]

Hello,
I have an arison clas evo boiler and I'm trying to figure out how to drain it for maintenance of radiators/emergencies/etc. Currently I just drain a radiator till the pressure drops.

In the manual it says the process is to loosen the the air release value, put a hose in the drain cock underneath and open it. Couple of questions:

1. In the picture below the pump on the far right is where it says the air release valve is also located, can anyone tell me how to loosen this valve, I'm presuming it's not the big brass screw (which will be the pump) and something to do with the white attachment on top of it, but the diagram isn't clear and the service manual says nothing

2. The red circle with the black dot on the far left is the CH pressure release valve connected to the escape pipe that leads outside and it triggered once many years ago when the fill valve got left semi-open. I'm wondering is this black dot in the circle a button and/or can I just manually do this to save connecting hose pipes, collecting/draining the water, etc.

thanks for any help.

 

[denso13]

Do you not have a drain cock for the heating? That's awfully complicated just to drain the boiler.

 

[denso13]

put a hose in the drain cock underneath and open it

It says the system drain, that isn't at the boiler,

 

[CBW]

Leave the pressure relief valve alone. No it’s not the brass screw or the white thing. The vent is the grey cap behind the pump.

 

[chucklepie]

It says the system drain, that isn't at the boiler,

View attachment 348040

Hello, on the underside of the boiler next to all the other valves is the drain cock. See image from the manual.So I'm asking how to 'loosen the automatic air relief valve' as I it's mentioned as being attached to the pump in my photo but no photos, but have no idea how to do it.

Releasing it here is simpler than using a radiator cock because the one on the boiler you can just let it empty into a giant bucket (or the sink in my garage) without needing to get the hose, put on a jubilee clip and run the hose outside

Noted about the pressure release.

Thank.s

 

[CBW]

So I'm asking how to 'loosen the automatic air relief valve' as I can see it but have no idea how to do it.

If it’s not already open, as it should be to be an auto air vent, then usually a 1/4 turn counter clockwise