On Mon, 03 Apr 2006 09:27:44 +0100, Derek Geldard
wrote:

On Sun, 02 Apr 2006 22:55:32 +0100, Tim
wrote:

They seem to have been de-emphasised now with the advance of sealed
systems and a better understanding of pumping -over.

Thanks Andy & Derek. Curiously the heating installation had this
deaerator and a couple of those ball float designs, which seemed a bit
redundant to me.

Derek, I am curious of your remark about the 'better understanding of
pumping'. Could you clarify this or point me to a URL please?


I also had the Myson one that Andy mentioned. That one was new and
boxed and came with an propaganda leaflet that illustrated all the
myriad possible "wrong" ways of setting up the feed and expansion,
flow and return piping, and the siting of the pump in order to avoid
such nasties as "pumping - over" or negative pressure in parts of the
system.

The leaflet implied the one sure fire way of avoiding all the problems
was by using a Myson Aerjec.

Apparently this was an issue of concern at the time, this was 25 years
ago. Since one encounters these things so infrequently and most new
build houses since then have been built with wet c/h without a
proprietory de-aerator, I presume that eventually the optimum set up
became the norm.

I could find no mention of de-aerators on the Myson site and their
piping layout diagrams don't include them.

DG

Yes, in terms of avoiding sucking down or pumping over, positioning
the vent pipe and FE pipe within 150mm of one another on the circuit
avoids the problem.

However, some people managed and still do manage to put one on each
side of the boiler (wrong because of boiler flow resistance) or worse
still on either side of the pump.

Air separators effectively force the plumbing to be done correctly.

The second aspect is that the design of the pot swirls the water and
helps get the air out after initial filling. I fitted one on a
system a few years ago that had has the FE and vent pipes simply
connected to the circuit within 150mm and it did make an improvement,
although not a vast one.

Better yet is to convert the system to sealed operation if the boiler
is OK for that.



--

..andy