On Mon, 7 Nov 2005 13:48:25 -0000, "TheScullster"
wrote:


"Andy Hall" wrote:

Thanks Andy, understand intruction except this next bit:

Once you've done this and got a clean system, make sure that *there is
no sucking down the vent pipe*.

Please can you clarify?

Phil


This is where the plumbing layout, and pump position are such that
there is a significant pressure differential between the vent and the
feed pipes. If it is in one direction, there can be pump over -
water trickles from vent into tank. In the other, air is sucked down
the vent. Either one causes repeated oxygenation of the water,
although suckdown tends to also produce a build up of air in
radiators.

It is caused if there is a pressure differential between the two
places where vent and feed pipes connect to the system and is quite
likely to happen if they are on opposite sides of the pump. However,
as little as a 30cm length of pipe between the two can cause problems.

Generally the best way is to make sure that they connect to points no
more than 15cm apart or to an air separator like a Myson Aerjec.



--

..andy