First time house owner here. Before I go cycling I apparently have to do some bloody stuff around the aforementioned house! I know!

How does one bleed a radiator system?

If you google, there seems to be alot of different advice!

ta!

Open screw, let out air, close screw, repeat for any radiators that aren’t warming properly, ride bike

have a cloth handy as you can get rust coloured water squirting out once the air has all escaped – makes a mess of walls / carpets….

Also, once you’ve bled the system you may have to top up the water pressure via the fill valve (normally below the boiler) if it’s a closed system.

If there are any really stubborn ones you may need to close off the rest

Switch off the heating (pump) before you start.

Should go without saying but just in case: loosen the bleed screw, don’t remove it completely.

If you do as DougieDogg says and close any radiators off, make sure you count the number of turns, so when you reopen the valves later on the radiators should still be balanced… 🙂

Auto Radiator Bleed Valve

Fit and forget.

Yes they spit and bubble and pop air and water out…. The rad will be fully bled when you are only getting free flowing water…. with no air in it and so no spitting or bubbling or popping.

As above … defo used a cloth close to/over the valve… as the water will stain and because of the spitting will go everywhere.

good luck

Pump Off
Check/top up system pressure
Bleed all rads
Check/top up system pressure
Ride Bike
(If the water is really black top up the system with corrosion inhibitor. If the water is really REALLY black, drain the system and top it up, adding corrosion inhibitor).

should they be warm/ on?

Doesn’t matter if they’re warm or cold, so long as the pump isn’t running.

If the water that comes out is black, make a note that it would be a good idea (at some point, not now) to flush the system and put fresh corrosion inhibitor in.

Edit – sorry, Smiffy said that!

You can bleed radiators with the pump running, you’ll get the air out the system faster as all the solenoids will be open. If the pump is off then the solenoids are closed and the CH system will only have one the return pipe open.

Yes, agree with footflaps, but if the pump is running then just be careful as there might be hot water circulating through the rad (check the temp at the bottom of the rad) so be careful about hot water spurting out of the bleed screw.

Even if the pump is running it could just be to heat up the hot water circuit so CH circuit might be isolated, so might be worthwhile manually opening the CH motorised valve. But to be honest I’ve never bothered with any of that and just bled the rads and had no issues.

^^^ As wobbliscot – I never do anything more scientific than open the bleed nipple of any/all offending radiators in whatever order I happen to wander around the house whenever I remember to do it and never had an issue in 25 years of home ownership.

…
Check/top up system pressure
Ride Bike

Come home to a cold house and annoyed wife because you forgot to turn the heating back on!

haha  i’m more confused now then when I first posted. It is a new house, completed in July last year, if that makes a difference

I’ll bimble around the house bleeding the radiators as i go, holding a towel to mop up any seepage (from the radiators).

i won’t check if the heating is on, or indeed anything else!

Cheers all!

As above but with one amendment:

You may get 1 or 2 rads that will not bleed the air out. If this happens, when you’ve bled the other rads turn them off at the TRV (valve at the bottom of each rad), then turn the heating on (solenoid will open, pump will run).

This kind of forces the air round the system to the pesky rads and will allow you to bleed them.

I found this out the hard way, after having a cold living room rad for ages cos i couldn’t bleed it properly.

I have one of these. Avoids spluttering mess.

That said, I’ve got a 25+ year combi system and I never get air out of any of the radiators using it, only clean water. No rust, sludge or anything to confirm I need a “power flush” or other snake-oil.

I do have an imbalance though. Lower hallway (huge) radiator being hottest and two in the middle upstairs never getting all that hot. I might have to try turning off the others and see what happens if I bleed the problem ones. Also, I have no TRVs, only old school valves. Small house though and the system is controlled reasonably well by a single room thermostat.

Just had a smashing bimble and bled them.

No air really came out except for the last one. It sounded like a shart.

Was enjoyable, would do again.

That said, I’ve got a 25+ year combi system and I never get air out of any of the radiators using it, only clean water. No rust, sludge or anything to confirm I need a “power flush” or other snake-oil.

We have a 35+ year old non-combi and no matter how many times I flush it, the water is dark brown and stinks of rust! Not that it seems to matter, system works fine bar a small leak I opened up in the back of the heat exchanger by using Fernox DS40 (citric acid) when descaling the boiler the other week. Second time it’s happened and it should eventually rust itself closed….

You may find you have one radiator that get’s air in – I tend to only have to bleed the main bedroom’s radiator, once in a blue moon.

I do have an imbalance though. Lower hallway (huge) radiator being hottest and two in the middle upstairs never getting all that hot.

At the risk of sounding all “snake oil” it might be worth trying to balance your radiators. Hallway radiator might be wide open and the water will take the path of least resistance through that if so. Try shutting one of the valves on the hallway radiator and seeing if the others heat up properly. If so, gradually open up the hallway radiator again so that it heats up without stealing water from the others.

You can bleed radiators with the pump running, you’ll get the air out the system faster as all the solenoids will be open.

If I did that I’d end up with more air in them, not less. Guess how I know?!