Ravenheat CSI85 central heating system losing pressure

[psarinuk]

Hi all.

My central heating has been losing pressure over the last few months @ 0.5 bar every week. Finally thought of going around the house to find a leak today.

Could not find anything, so thought I would add Ferrox leak repair through one of the radiators. For some reason I thought of checking the boiler itself and found plenty of corrosion and water patch around the Air Purge Valve as shown below.

My question is about whether it would be right to replace this air purge valve or do all valves become like this? Do air purge valves hold water?

I am assuming I did not see a patch below the boiler as it leaks when its ON and therefore water from minor leak evaporates due to boiler being HOT. Any buyers for this story?

Your early response would be highly appreciated.

Thanks.

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[transam]

Its an automatic air vent , has a float inside it , yep they all leak eventually

needs changing . Incidentally u would be advised not to take the combustion chamber off !!!!

 

[psarinuk]

Thanks for your reply. what does this valve do?
Is that true that I need to isolate the boiler and drain it, before it is removed?
Do I need to do anything else after the new one is installed?
The boiler manual says that the black plastic cap at top should be left open permanently by 1 turn.
Don't think this was done before, should that have caused this leak?