Hi everybody. My sister has a problem. I've noticed that most of her
rads are hot at the bottom and cold at the top. When I bleed them some
air comes out and then nothing, no more air. After the air finishes
coming out it is not followed by water, as I'd expect. Nothing at all
happens. Should I be bleeding them with the system OFF as I am doing?
Or should I turn the system ON and then try bleeding. The rads are fed
by a combi boiler and this "air problem" has been prevalent since the
combi was installed about a year ago. Any ideas?
Thanks, mr J

Sounds like air lock if youre sure lbleed nut fully unwound.
Leave system on to pump water through, and take bleed nut all way out
and wait.
Be ready to fit back in as soon as you feel heat at top of rad/hear
gurgling, but leave open until you see some dirty water dribbling out.

Gel wrote:
Sounds like air lock if youre sure lbleed nut fully unwound.
Leave system on to pump water through, and take bleed nut all way
out and wait.
Be ready to fit back in as soon as you feel heat at top of
rad/hear gurgling, but leave open until you see some dirty water
dribbling out.

"The rads are fed by a combi boiler... "

Mr J, no more water is coming out because it's a sealed system, and some of
the thermostatic valves are closed. There's no incoming water arriving in
the radiator to displace the air.

You need to open the thermo rad valves, and then find the mains valve which
lets water into the system. It'll be under the boiler, in some kind of
short flexible loop. Open it, wait for pressure to be indicated @ 1 bar
before closing, and then go back and bleed some more. You might have to
repeat this cycle a few times.

thanks, ill try that. mr J

On 28 Jan 2006 08:15:31 -0800, "mr j" wrote:

Hi everybody. My sister has a problem. I've noticed that most of her
rads are hot at the bottom and cold at the top. When I bleed them some
air comes out and then nothing, no more air. After the air finishes
coming out it is not followed by water, as I'd expect. Nothing at all
happens. Should I be bleeding them with the system OFF as I am doing?
Or should I turn the system ON and then try bleeding. The rads are fed
by a combi boiler and this "air problem" has been prevalent since the
combi was installed about a year ago. Any ideas?
Thanks, mr J

Is the system at the correct pressure?
It sounds like it is almost empty.

Ive just rang her and she's topped it up using the filling loop. It was
nearly on empty. Tomorow I shall bleed her rads for her. Is it positive
that I bleed with the pump pumping water round the rads? mr J

"mr j" wrote in message
oups.com...
Ive just rang her and she's topped it up using the filling loop. It was
nearly on empty. Tomorow I shall bleed her rads for her. Is it positive
that I bleed with the pump pumping water round the rads? mr J


It won't matter that thermostatic valves may be closed as water will pass up
the other pipe to displace the air. As it is a closed system the pressure
head is the same at both ends of the radiator.

Remember to check the pressure after bleeding.


John

In article .com,
mr j wrote:
Hi everybody. My sister has a problem. I've noticed that most of her
rads are hot at the bottom and cold at the top. When I bleed them some
air comes out and then nothing, no more air. After the air finishes
coming out it is not followed by water, as I'd expect. Nothing at all
happens. Should I be bleeding them with the system OFF as I am doing?
Or should I turn the system ON and then try bleeding. The rads are fed
by a combi boiler and this "air problem" has been prevalent since the
combi was installed about a year ago. Any ideas?

I'd be concerned where the water is leaking to.

--
*Don't use no double negatives *

Dave Plowman London SW
To e-mail, change noise into sound.

I don't believe any water is leaking anywhere. She had the combi fitted
when she qualified for a Government grant and from what she tells me
(A) the system was never bled in the first place as the fitters told
her that it "bled itself automatically" and (B) the rads have never
worked at proper temperature since the combi was fitted. A lot of
'effing and blinding from the lads who fitted it but no aftercare.She
was never told about the filling loop and she now tells me that the
instructions suggest regular checking of the pressure and how to top up
the system using the filling loop. I think it's a fine system (it cost
her nowt) but it just needs bleeding. Everytime I bled it I knew
nothing about refilling the system using the filling loop. To
recap,tomorrow when I bleed it, should I bleed it with the system on
then? - and fill the system accordingly. mr J

mr j formulated on Saturday :
Hi everybody. My sister has a problem. I've noticed that most of her
rads are hot at the bottom and cold at the top. When I bleed them some
air comes out and then nothing, no more air. After the air finishes
coming out it is not followed by water, as I'd expect. Nothing at all
happens. Should I be bleeding them with the system OFF as I am doing?
Or should I turn the system ON and then try bleeding. The rads are fed
by a combi boiler and this "air problem" has been prevalent since the
combi was installed about a year ago. Any ideas?

The answer is in your final sentance, the mention of 'combi boiler'. If
you release air from these systems, then you need to replace it with
water. As a combi is a sealed system, as you bleed the air out the
pressure in the system will gradually be lost.

What you need to do is find the filling loop, which will probably be
somewhere near the boiler and top it up. The filling loop allows you to
top up the system water with water from the water mains. A gauge on the
boiler will indicate the system pressure, which should be between 1 and
2 bar once it is filled up and fully bled.



--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In an earlier contribution to this discussion,
mr j wrote:

I don't believe any water is leaking anywhere. She had the combi
fitted when she qualified for a Government grant and from what she
tells me (A) the system was never bled in the first place as the
fitters told her that it "bled itself automatically" and (B) the rads
have never worked at proper temperature since the combi was fitted. A
lot of 'effing and blinding from the lads who fitted it but no
aftercare.She was never told about the filling loop and she now tells
me that the instructions suggest regular checking of the pressure and
how to top up the system using the filling loop. I think it's a fine
system (it cost her nowt) but it just needs bleeding. Everytime I
bled it I knew nothing about refilling the system using the filling
loop. To recap,tomorrow when I bleed it, should I bleed it with the
system on then? - and fill the system accordingly. mr J

No, bleed it with the boiler off - but check that you have about 1 bar
pressure in the system before you start - topping up with the filling loop,
as necessary. As you bleed air and/water out, the pressure will drop. So
check it frequently during the bleeding operation and top up when it gets
low. When you've finally finished, make sure that the cold pressure is about
1 bar and then disconnect the filling loop.
--
Cheers,
Roger
______
Please reply to newsgroup.
Reply address IS valid, but is disposable in the event of excessive
spam.

Cheers. mr J

mr j wrote:

Ive just rang her and she's topped it up using the filling loop. It was
nearly on empty. Tomorow I shall bleed her rads for her. Is it positive
that I bleed with the pump pumping water round the rads? mr J

Have a read through the filling and bleeding procedure he

http://www.makewrite.demon.co.uk/SealedCH.html



--
Cheers,

John.

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In article ,
Mike Harrison writes:
On 28 Jan 2006 08:56:51 -0800, "mr j" wrote:

Ive just rang her and she's topped it up using the filling loop. It was
nearly on empty. Tomorow I shall bleed her rads for her. Is it positive
that I bleed with the pump pumping water round the rads? mr J

Yes, but before it has time to heat up too much - you don' want scalding water coming out!

but on the other hand, the hotter the water, the more air will
come out of solution.

--
Andrew Gabriel

On 28 Jan 2006 08:56:51 -0800, "mr j" wrote:

Ive just rang her and she's topped it up using the filling loop. It was
nearly on empty. Tomorow I shall bleed her rads for her. Is it positive
that I bleed with the pump pumping water round the rads? mr J

Yes, but before it has time to heat up too much - you don' want scalding water coming out!

Thanks for all your help on sorting out my sisters rads. I went round
earlier and bled the system, topping up with the filling loop as I went
along. All rads now flow hot top and bottom. Thanks for helping. mr J

Gel wrote:
Sounds like air lock if youre sure lbleed nut fully unwound.
Leave system on to pump water through, and take bleed nut all way out
and wait.
Be ready to fit back in as soon as you feel heat at top of rad/hear
gurgling, but leave open until you see some dirty water dribbling out.

So if you miscalculate and the water starts spraying out of the
completely unscrewed bleed nut, how are you gonna get that bleed nut
back in? Even small amounts of water pressure can be really hard to
fight, I've been there...

In an earlier contribution to this discussion,
cs wrote:


So if you miscalculate and the water starts spraying out of the
completely unscrewed bleed nut, how are you gonna get that bleed nut
back in? Even small amounts of water pressure can be really hard to
fight, I've been there...

Turn off both valves a bit rapidly?
--
Cheers,
Roger
______
Please reply to newsgroup.
Reply address IS valid, but is disposable in the event of excessive
spam.

Ive just rang her and she's topped it up using the filling loop. It was
nearly on empty. Tomorow I shall bleed her rads for her. Is it positive
that I bleed with the pump pumping water round the rads? mr J

It matters little on a sealed system at 1 bar pressure, although it is safer
off, as any water spray will be cold. On a gravity system, you need to turn
it off, as the pressure within the pipework can be sub ambient pressure, so
it sucks air in.

Christian.