Bleeding a radiator

Legacy_user

When you bleed a radiator normally, you allow any air to escape then when water starts to trickle,you close the tap. We have a condenser boiler, so presumably you wouldn't attempt to bleed the rad when the boiler was off, as once the air was out no water would come, so one would assume it best to bleed when the boiler was on?, is this so please.

partan

im assuming you mean a combi-boiler? if so, the system is pressurised, this is what pushes the air out. make sure you check the water pressure on the boiler, and top it up if necessary.

macman

Whether it's a condensing boiler or not makes no difference to how you bleed the rads.
Water will continue to flow out until you close the bleed valve. If you are bleeding a combi then eventually the level will fall below the bleed valve level (if you left it open long enough). With a conventional system the system is topped up from the header tank as necessary.

Lucero_2

You should always bleed when the heating is on anyway (otherwise you won't know where the air locks are).

With a condenser boilers, as was said, if you have to bleed too much the pressure in the boiler will drop and will need topping up

penrhyn

Best to bleed radiators when cold and the boiler off. The pressure gauge on the boiler should be checked afterwards, and if the pressure has fallen below 1 bar ( or what the mfg recommends)then more water should be run in via the filling loop.


With all this conflicting advise I think we need a plumber!!

spadoosh

Yeh i would bleed it whislt its off, not thanks to spluttering hot water in my face.

Anthonis

Blue is air, red is water....
Now if you have lots of air in system, ensure that your pressure level would be slightly bigger than it is stated on manual. Top up system on cold. Now turn on heating, with heating always goes on water pump so water start circulating and if the is any air it will get to the radiator... Wait 5-10 mins and then bleed, do not turn off heating as with it stops pump... Bleed till air stops and water starts..... Then repeat same on others as air can easily circulate to other places, usually higher spots.... When you finish again check pressure in system if its not to low on cold...

ChiefGrasscutter

Often the first radiator after the boiler in the heating circuit will accumulate most of the air.

Lucero_2

So the heating should be on when you bleed, after all, cold water is denser than hot so you might not even know you have a problem.

zeeshan_ali2525

I keep getting air in a couple of radiators. Someone suggested getting self bleeding radiator valves.

espresso

The heating should be off when bleeding radiators as air can actually be drawn in if the water is being circulated by the pump when the bleed valve is opened. Any air should collect at the highest point in the heating system e.g. in an upstairs bathroom with a tall towel warmer. Central heating inhibitor e.g. Sentinel X100 should be added annually to prevent corrosion, limescale and to keep the sytem running efficiently. If the system is pressurised the system pressure needs to be checked after bleeding.