help, bleeding radiator, think i goofed up

weetsie

Novice Member
so i made the mistake of assuming i knew how a central heating system worked and i tried to bleed the radiator in my room which was half empty and possibly completely empty now.

anyway, i figured that a radiator has two valves, so all i needed to do is close the outlet, open the inlet, turn the heating on and open the bleed screw and as the water came in, it would just fill the radiator and the hole in the top i opened would allow the air to exit without going into the system.

well it didnt work and i dont know why, so i resorted to google and all of the guides say i should turn the heating off or i could add more air to the system??? :confused:

this makes no sense to me but i tried it anyway and nothing happened, i would of expected either nothing or more air going into the radiator as surely when the heating is off there is nothing to pump the water up and making a hole in the top of the system would surely just allow the water to drop back downstairs to the tank?

eh, i am totally lost and my mum is going to be ****ed when she gets home if i have broken the central heating and she has to fix it, any ideas where i am going wrong?
 

sniffer66

Distinguished Member
You don't need to close either valve when bleeding a rad. Your system will be self filling from the header tank, so all you need to do is turn off the heating, return both valves to the position they were before you bled, then bleed again. The incoming water pressure will force the air from the rad - just remember to have a cloth near the rad key to catch any excess water
 
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Stu V

Well-known Member
If all you are trying to do is remove air from the radiator then you need to open the valve at the top of the radiator with the central heating on and wait for the water to start coming out of it and then quickly shut it (keep a cloth handy). You don't need to worry about the inlet/outlet valves. That's how I have always done it.

Edit - Beaten to it
 

IronGiant

Moderator
The pump will be much happier sucking air in through the bleed valve than pumping the water round a sealed system, so, unfortunately you probably have introduced more air into the system :(. You should do it with the heating off.

Don't panic: yet.

Put the inlet and outlet valves back to where they were before you started. (They are usually set so all the radiators in the house have the same rate of water flow through them so if you don't know where they were, you have buggered up to some extent.) With them set as they were( :rolleyes:) or if you don't know where they were both fully open turn the heating off and then bleed that radiator until water comes out of the bleed valve. If you think you may have introduced air into the system then try bleeding the other radiators as well.

If it's a combi you will need to check the pressure guage on the boiler to check the system is at the right pressure. If all is well, turn the system on. Check that your radiator is now getting hot, but not much hotter than the others, if it is hotter, turn down the inlet valve until it matches the others in temperature ( or keep quiet and enjoy the extra heat ;)).

If in any doubt... confess.
 

weetsie

Novice Member
ok heating is off, both valves open and nothing is happening.

what incoming water pressure will their be when the heating is off? i dont get it :(

edit: didnt see last two posts before i posted this post.

@IG my radiator hasnt been used for a year or so, and both valves were shut off completely and it is a combi

If all you are trying to do is remove air from the radiator then you need to open the valve at the top of the radiator with the central heating on and wait for the water to start coming out of it and then quickly shut it

that was what i was trying to do origionally but it didnt seem to work.
 
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sniffer66

Distinguished Member
ok heating is off, both valves open and nothing is happening.

what incoming water pressure will their be when the heating is off? i dont get it :(


Assuming you have a similar system to me the pressure will come because water finds its own level. The header tank is located above the radiators (think of the header tank as being like a toilet cistern that refills when water is removed) if you release air from a rad then water will take its place as the topmost level of the water is ABOVE the rads
 

weetsie

Novice Member
Assuming you have a similar system to me the pressure will come because water finds its own level. The header tank is located above the radiators (think of the header tank as being like a toilet cistern that refills when water is removed) if you release air from a rad then water will take its place as the topmost level of the water is ABOVE the rads


OH well that makes sense, however while i dont know where the tank is, its definately down not up.

now what? :D
 

nonumb

Well-known Member
If no air is coming through then surely it means there isnt enough pressure in the system? Surely open all valves with the heating on check the pressure and then open the bleed valve? Thats what I've always done.

Edit this is assuming you have a combi?
 

IronGiant

Moderator
I'm up for being corrected on this but the pump doesn't pressurise the system, that's either from weight of the water in the header tank in a conventional system or mains pressure in a combi. If there is no pressure in a combi you need to reintroduce mains water into the system until the pressure gauge on the boiler shows the right pressure.

1) check the pressure gauge on the boiler and report back :)
 
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IronGiant

Moderator
Good point. Also, do you know why the rad was shut off?
 

SBT

Banned
I did mine the other night,the top of the rad in the bathroom was cold,just put the key in the top right of the rad turned a bit,hissed for a few seconds then water came out.Rad is now hot,simples :D
 

weetsie

Novice Member
ok found the tank, its in the cellar so i cant see it being physically possible to bleed it while having both valves open.

and the valves are fine, you can hear the water rushing through when you open them and also the radiator does and doesnt get hot when you have them open/closed.

@IG it was shut off because i shut it off because it made my nose all stuffy but right now that is preferable to being able to see my breath in the morning.
 

Ruperts slippers

Distinguished Member
There is no header tank with a combi,just find the filling loop and open the valves and refill between 1-1.5 bar then turn the boiler on to let the boiler expel and air inside the boiler..
If you have no luck with that the valves maybe duff or the pipes blocked...
 

weetsie

Novice Member
ok its at just under 0.5 bar and i have found the bit on changing the pressure in the manual.

brb wish me luck

edit: i spoke to my mum on the phone and said "i started bleeding the radiator.." and she said "DONT TOUCH IT RING YOUR DAD!"

anyway i read the manual and i was confident i knew what i was doing so i opened the first valve (air or something) then opened the second valve which slowly made the pressure gauge increase, i left it at 1.5 bar.

i then closed the outlet like before and opened the inlet and unscrewed the bleed screw and air whistled out and me assuming my radiator was half empty and this was going to take 5 minutes to fill left it and started typing this sentence till i heard water ****ing all over the floor.

anyway i just heard my mum pulling into the garage and all is well so thanks guys!
 
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Ruperts slippers

Distinguished Member
ok its at just under 0.5 bar and i have found the bit on changing the pressure in the manual.

brb wish me luck

edit: i spoke to my mum on the phone and said "i started bleeding the radiator.." and she said "DONT TOUCH IT RING YOUR DAD!"

anyway i read the manual and i was confident i knew what i was doing so i opened the first valve (air or something) then opened the second valve which slowly made the pressure gauge increase, i left it at 1.5 bar.

i then closed the outlet like before and opened the inlet and unscrewed the bleed screw and air whistled out and me assuming my radiator was half empty and this was going to take 5 minutes to fill left it and started typing this sentence till i heard water ****ing all over the floor.

anyway i just heard my mum pulling into the garage and all is well so thanks guys!

What do u mean by the outlet,both valves should be open when filling the rad,and yes it doesnt take long,so no need to leave the room,and never take the nipple completely out otherwise you might loose it...
 

weetsie

Novice Member
What do u mean by the outlet,both valves should be open when filling the rad,and yes it doesnt take long,so no need to leave the room,and never take the nipple completely out otherwise you might loose it...

this is true, turns out when the pressure is right you dont need to close the outlet. i discovered that when my sisters radiators outlet was missing so i did it without closing it and it worked fine.
 

IronGiant

Moderator
I can think of nothing worse than not being able to find a nipple when you need it... :devil:

I'll get me coat.
 

IronGiant

Moderator
BTW, glad you got it sorted in the nick of time Weetsie :thumbsup:
 
If all you are trying to do is remove air from the radiator then you need to open the valve at the top of the radiator with the central heating on and wait for the water to start coming out of it and then quickly shut it (keep a cloth handy). You don't need to worry about the inlet/outlet valves. That's how I have always done it.

Edit: [-]This is WRONG.[/-] I thought this was wrong, but apparently this is actually correct. Having the pump running whilst doing the bleeding will help remove any air locks from the system

[-]When you are bleeding the air out of radiators, then the only thing shoving air out of the bleed valve at the top of a radiator should be pressure of water from the heating system's header tank in the loft.[/-]

So to get this state of affairs, the central heating pump should be [-]OFF[/-] ON.

The easiest way to make sure the pump is OFF is to turn down the thermostat to its lowest postion.

Edited: Then bleed the radiators, starting with the one that is furthest from the boiler and working your way from [-]upstairs to[/-] downstairs to upstairs.

Don't forget to re-set the thermostat to re-start the pump.
 
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One further note:

Don't start messing with the radiator valves unless you really have to, otherwise you will lose the 'balance' of the radiator.

Ideally in a house, all the radiators should have had their individual valves adjusted, so that when the central heating is on, they can all be on at the same time and no individual room gets too hot or too cold. If this can be achieved then 'the radiators are balanced'.
 

Ruperts slippers

Distinguished Member
This is WRONG.

When you are bleeding the air out of radiators, then the only thing shoving air out of the bleed valve at the top of a radiator should be pressure of water from the heating system's header tank in the loft.

So to get this state of affairs, the central heating pump should be OFF.

The easiest way to make sure the pump is OFF is to turn down the thermostat to its lowest postion.

Then bleed the radiators, starting with the one that is furthest from the boiler and working your way from upstairs to downstairs.

Don't forget to re-set the thermostat to re-start the pump.

The correct way is start downstairs then work your way up..And airlocks can be removed with the pump and boiler running...
 
Aaaargh!

The correct way is start downstairs then work your way up..

I bow to your greater knowledge. Many thanks, Oh Wise One.

I will duly edit my post as you indicate.
 

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