Pressure should be 1.5 bar max,just drain some water out a rad up stairs till you get pressure down,never bleed rads with heating on 
Not on mine....min is 1.2 bar max is 3 bar, so 2 bar is about in the middle and if the pressure does go over 3 bar, it will release the pressure itself
I'm more intrigued as to where the air came from 
This might be part of the problem. You will have air dissolved in the water in the system from the start. Once that air has been purged, there shouldn't be the need to bleed constantly unless the system is deteriorating through lack of inhibitor. A good inhibitor will contain deoxygenating chemicals to promote this.
If you are having to top up regularly, you are introducing fresh water containing air, so will also be bleeding regularly.
As to the correct pressure to run the system at, it's not an arbitrary choice. The system will contain a pressure vessel inside which an air bladder is charged to a certain pressure. As the system reaches this pressure, the pressure vessel will start to contain the expansion of the water in the system by compressing air in the bladder. This will limit the pressure rise as the system heats.
You really only want to adjust the pressure when the system is stone cold, and you should set it to about the same pressure as the charge in the air bladder. Typically, this will be not more than 1.5 BAR although how it was set at installation depends on the system. Set it to a higher pressure and you have used up some or all of the expansion volume available in the pressure vessel so when the system heats up you may have a problem. If you run out of expansion space the system will hit 3 BAR when it's hot and blow off the relief valve. You'll then notice the pressure has dropped when it's cold and top it up again, and so begins the cycle that admits air and waters down the inhibitor.
Furthermore, if the relief valve operates regularly, it'll only be a matter of time before it gets a bit of crud stuck in it and starts weeping, meaning you'll keep topping up, and keep bleeding...
Another issue is where the bladder in the expansion tank has punctured. The expansion volume of air leaks away (maybe ending up in a radiator)
and you top up the system but end up with no expansion space. So, you top up to maybe 1 or 1.5 BAR cold, and as soon as the system warms up it rises quickly to 3 BAR and lifts the relief valve. Once it cools down, there is nothing to take up the contraction of the water, so it'll draw air in, often through an automatic bleed valve or a weak joint, or the hole in the expansion tank bladder, and you'll be bleeding regularly to remove it...
In your position, I would bleed all the radiators, set the pressure to 1 BAR when it's stone cold, and watch what happens when it warms up. I would expect the pressure to rise to 1.5 BAR or so, and to drop to 1 BAR again when cold. I would expect that it doesn't need any further filling or bleeding. If it does, or if the pressure strays outside those limits, something's not right.
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Topic: Air in a central heating rad (Read 2807 times)