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How do air separators work?



 
 
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  #1  
Old January 8th 05, 12:22 PM
Set Square
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Default How do air separators work?

Air separators - such as Screwfix 90641 have been mentioned from time to
time.

They seem to consist of two concentric cylinders, with four connections -
one each end and two off the side, near the ends.

Can anyone enlighten me as to:
* How they work (what's inside?)
* Where to put them in the circuit?
* How to connect them - what are the 4 tappings for?

TIA.
--
Cheers,
Set Square
______
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  #2  
Old January 8th 05, 02:02 PM
Andy Hall
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On Sat, 8 Jan 2005 12:22:12 -0000, "Set Square"
wrote:

Air separators - such as Screwfix 90641 have been mentioned from time to
time.

They seem to consist of two concentric cylinders, with four connections -
one each end and two off the side, near the ends.

Can anyone enlighten me as to:
* How they work (what's inside?)
* Where to put them in the circuit?
* How to connect them - what are the 4 tappings for?

TIA.



I'm not sure about that specific one, but the principle is that you
bring the feed/expansion pipe, the vent and an in/out connection to
the circuit together, with the vent at the top.

The water in the circuit passes through the chamber and air bubbles
rise out from it. Some of them have a baffle or equivalent
arrangement inside to provide a longer path (more time) in the
chamber.

http://www.bes.ltd.uk/products/106.asp (look at Aerjec)

Apart from separating air out, because the vent and feed pipes join at
a common location, there should be no pump over or suck down either.



--

..andy

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  #3  
Old January 8th 05, 03:06 PM
Set Square
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Posts: n/a
Default

In an earlier contribution to this discussion,
Andy Hall wrote:

On Sat, 8 Jan 2005 12:22:12 -0000, "Set Square"
wrote:

Air separators - such as Screwfix 90641 have been mentioned from
time to time.

They seem to consist of two concentric cylinders, with four
connections - one each end and two off the side, near the ends.

Can anyone enlighten me as to:
* How they work (what's inside?)
* Where to put them in the circuit?
* How to connect them - what are the 4 tappings for?

TIA.



I'm not sure about that specific one, but the principle is that you
bring the feed/expansion pipe, the vent and an in/out connection to
the circuit together, with the vent at the top.

The water in the circuit passes through the chamber and air bubbles
rise out from it. Some of them have a baffle or equivalent
arrangement inside to provide a longer path (more time) in the
chamber.

http://www.bes.ltd.uk/products/106.asp (look at Aerjec)

Apart from separating air out, because the vent and feed pipes join at
a common location, there should be no pump over or suck down either.



Thanks for that. Presumably they can only be used in vented - and not
sealed - systems?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.


  #4  
Old January 8th 05, 03:49 PM
Peter Andrews
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Default


"Andy Hall" wrote in message
...
On Sat, 8 Jan 2005 12:22:12 -0000, "Set Square"
wrote:

Air separators - such as Screwfix 90641 have been mentioned from time to
time.

They seem to consist of two concentric cylinders, with four connections -
one each end and two off the side, near the ends.

Can anyone enlighten me as to:
* How they work (what's inside?)
* Where to put them in the circuit?
* How to connect them - what are the 4 tappings for?

TIA.



I'm not sure about that specific one, but the principle is that you
bring the feed/expansion pipe, the vent and an in/out connection to
the circuit together, with the vent at the top.

The water in the circuit passes through the chamber and air bubbles
rise out from it. Some of them have a baffle or equivalent
arrangement inside to provide a longer path (more time) in the
chamber.

http://www.bes.ltd.uk/products/106.asp (look at Aerjec)

Apart from separating air out, because the vent and feed pipes join at
a common location, there should be no pump over or suck down either.



--

.andy

To email, substitute .nospam with .gl


I'm sure I'm missing something... surely fitting these masks any problems -
if I have to continually bleed a radiator then I would look for where air is
getting into the system - with one of these fitted I'd never know.

Peter


  #5  
Old January 8th 05, 04:14 PM
nick smith
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Default


"
I'm sure I'm missing something... surely fitting these masks any problems -
if I have to continually bleed a radiator then I would look for where air is
getting into the system - with one of these fitted I'd never know.

Peter


Also will bleed out any gases produced that are not soluble in water.
I've got one on one of our systems - not sure how good it is though.
Nick


  #6  
Old January 8th 05, 04:51 PM
Andy Hall
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Default

On Sat, 08 Jan 2005 15:49:58 GMT, "Peter Andrews"
wrote:


I'm sure I'm missing something... surely fitting these masks any problems -
if I have to continually bleed a radiator then I would look for where air is
getting into the system - with one of these fitted I'd never know.

Peter


I would look at it the other way round.

You shouldn't be getting air sucked into the system via the vent when
one of these is installed, so this leaves only joints for introduction
of air.

The more typical scenario of gas build up in radiators if it isn't
suck down from the vent is hydrogen from corrosion and that's a
different issue. You will still get some build-up of hydrogen in
radiators.




--

..andy

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  #7  
Old January 8th 05, 05:04 PM
Andy Hall
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Posts: n/a
Default

On Sat, 8 Jan 2005 15:06:12 -0000, "Set Square"
wrote:


Thanks for that. Presumably they can only be used in vented - and not
sealed - systems?


Yes.

It would be pointless having one in a sealed system anyway, because
generally once the initial air and dissolved air is removed, there
should not be anything much more unless there is a joint which allows
air to be sucked in. The more likely situation is hydrogen from
corrosion.

For a sealed system you can use an automatic air vent, or there are
suitable air separators. I used both on my system, with a Reliance
air separator. This goes inline in the circuit and is a vertical
column with stainless steel screen inside to help separate out the air
and a relief valve on the top.

Take a look at www.rwc.co.uk

Unfortunately the search on this site isn't great but the info is
there. Do a search on the site using keywords "heating" and
"products" and you will get a clickable link to a page with a diagram
of a house.

Scroll down and you will find air separators. e.g. ASEP 192 103

They look like a robot's genitals.....

These devices collect the small amount of air that may gather and can
be periodically purged by unscrewing the gap and pressing the button
inside.



--

..andy

To email, substitute .nospam with .gl
  #8  
Old January 8th 05, 06:55 PM
Senior Member
 
First recorded activity by DIYBanter: Dec 2004
Posts: 174
Default

Quote:
Originally Posted by nick smith
"
I'm sure I'm missing something... surely fitting these masks any problems -
if I have to continually bleed a radiator then I would look for where air is
getting into the system - with one of these fitted I'd never know.

Peter


Also will bleed out any gases produced that are not soluble in water.
I've got one on one of our systems - not sure how good it is though.
Nick
They are sometimes necessary because at the position of the T where the open vent comes off there is a slight negative pressure which prevents the air in the system from escaping at this point while the pump is running. This can cause a build up of air which eventually leeds to steam. The old way of dealing with this was quite effective, it was to put a T one size larger than the pipe size at this point, i.e. a 28mm T for 22mm pipes. The expansion so caused allows the air to escape during normal operation. There is no benefit to leaving the air in your system so you can blead it through a rad vent that I can think of. You always get gas created anyway, you don't need your radiators to be telling you that. Let it go free!
 




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