I'm a little stumped over how to bleed a radiator in a friend's house. His radiator, which is cold at the top but hot at the bottom, has a bleed valve at the bottom. When I loosen it, a healthy spurt of warm water shoots out. How am I meant to empty the air which I presume has gathered at the top of the radiator?

It has the bleed valve at the BOTTOM of the radiator? :confused:

You sure there isn't one at the top anywhere?

Are you absolutely sure that there isn't another bleed valve hidden around the back of the radiator at the top with a plastic cap on it? I have fitted radiators in my house from wickes which have this feature.

If not, it sounds like someone has fitted the radiator incorrectly. And if it were me I'd take it off and fit it the right way around.

But I am not a plumber, just a very handy engineer. Maybe a real plumber has a better idea

A bleed valve at the back? Hmm, never thought to look actually, there may well be one. But yes, this one is at the bottom with the thermostat at the other side - the top two ends are just blank metal caps. I'll nip over and check the back of the radiator tonight. Thanks for the suggestions.

edit: all of the radiators in the house (council property) are of the same design.

Originally posted by Ant
But yes, this one is at the bottom with the thermostat at the other side - the top two ends are just blank metal caps. I'll nip over and check the back of the radiator tonight. Thanks for the suggestions.

That doesn't sound like a bleed point, it sounds more like a drain hole to empty the radiator.

If it is a sealed system then you can't bleed the system. If there is no header tank which would be located hopefully several feet above the height of the highest radiator in the house then stop letting water out because the system will just be emptying of water and so making the situation worse A sealed system can be topped up by putting water in from a tap usually near the boiler but it is a bit of a pain forcing all the air out of the radiators..

It sounds like a sealed system then - there's certainly no bleed point behind the radiator. I'll pass the problem over to someone who knows what they're doing.

Thanks everyone.

Keep us posted Ant. You've got us interested now ;)

Sorted.

There was a 4mm plastic cap that sat flush in the bleed point cavity that made it look just like a round flat decorative feature in the centre of the screw-in nut. Basically we had to smash the thing off with a screwdriver.

Glad you got it sorted.

Incidentally, did you know that a 'small' radiator key is known as "a little bleeder"? Oh, and one of these that is especially designed to adjust valves on the opposite side of the radiator is known as "a right little bleeder".

Originally posted by WallBuilder
If it is a sealed system then you can't bleed the system. If there is no header tank which would be located hopefully several feet above the height of the highest radiator in the house then stop letting water out because the system will just be emptying of water and so making the situation worse A sealed system can be topped up by putting water in from a tap usually near the boiler but it is a bit of a pain forcing all the air out of the radiators..
Of course you can bleed a sealed system in exactly the same way as you would with a traditional tank fed system. Sealed systems are mainly found nowadays on combi boiler systems, but the air still has to be removed in order to fill it with water ( laws of physics and all that). The only difference is that you have to top it up manually, with water from the main inlet via the filling loop,( a length of flexible pipe usually located near the boiler). When the system is full and all radiators bled, the pressure as seen on the pressure gauge on the front of the boiler should read approx. 1-1.5 Bar. Job done.

Originally posted by Sam Miguel
Incidentally, did you know that a 'small' radiator key is known as "a little bleeder"? Oh, and one of these that is especially designed to adjust valves on the opposite side of the radiator is known as "a right little bleeder".

:lol: :lol: Lovin it. :D

Incidentally if you weren't able to find a bleed valve (some of the newer council heating systems have their bleed valves removed so that tenants can't mess with them) then you could always carefully take a wrench to one of the upper metal caps and loosen it a little until you hear air coming out. Then all you have to do is quickly tighten it when water starts dripping out. Careful how much you open it though as you really don't want it to come all the way off. :nono: Might be an idea to put a cloth underneath as well because that water can get pretty dirty. :gag:

And don't overtighten the nut! Council radiators seem to use cheap plastic washers that split easier than they squeeze.:|

Originally posted by Magneteer
Of course you can bleed a sealed system in exactly the same way as you would with a traditional tank fed system. Sealed systems are mainly found nowadays on combi boiler systems, but the air still has to be removed in order to fill it with water ( laws of physics and all that). The only difference is that you have to top it up manually, with water from the main inlet via the filling loop,( a length of flexible pipe usually located near the boiler). When the system is full and all radiators bled, the pressure as seen on the pressure gauge on the front of the boiler should read approx. 1-1.5 Bar. Job done.

I've known people with a sealed system open a bleed valve and then just expect the air to come out and the radiator to refill with water. My entire post did read that you had to manually put water into the system to get the desired effect,so I'll retract my earlier statement that sealed systems cannot be bled and instead just say it's not as straight forward as a system with a header tank.
Guess what I'm doing tomorrow?

sealed systems can be bled of air, but as pointed out in this thread have to be refilled from a valve near the boiler (usually on combi systems). easy enough to do I reckon, should take you all of 15 minutes. Dont forget to close the valve again after refilling the loop, as thats a fresh water inlet and should not be left open.

Originally posted by 1Man&hisBMW
Dont forget to close the valve again after refilling the loop, as thats a fresh water inlet and should not be left open.
Technically, the filling loop shouldn't be left for an end user to play with. It should be for the plumbers only! I've yet to come across a sealed system that hasn't got the filling loop fitted.

Originally posted by Lurch
Technically, the filling loop shouldn't be left for an end user to play with. It should be for the plumbers only! I've yet to come across a sealed system that hasn't got the filling loop fitted.

the filling loop is fitted on all combis I have seen, and most manuals instruct on how to fill the loop anyway. the only thing usually missing is the lever on the valve, but most fitters even leave this on. still how much would it cost to have a plumber out to do the job?

I've come across one or two that have their filling loops removed and metals caps covering the non-return valve, although like you say most of them still have their filling loops attached. It's not too good for the system really as they have been known to pass and then you get pressure loss on your system. Best to keep an eye on it and make sure your cold-setting system pressure is always around 1-1.5bar.

And yes, don't leave the tap open on a filling loop. A certain forum member (who shall remain nameless) once called me up saying his boiler was leaking. After attempting to blow some of the pressure off, draining it off and refilling we realised that his other half had been playing around and had left the tap from the cold feed wide open so the system pressure was nearly up to 4Bar. OUCH! :lol: