On Tue, 28 Mar 2006 11:29:33 +0100, "TheScullster"
wrote:

If it's a combi, aren't the heating and DHW sides separate?
How does the internal state of the CH system affect the DHW side of the
boiler heat exchanger?
[snip]
Yes the CH and DHW sides are seperate but the water that is
circulating around the rads (and is therefore nice and hot) is
diverted through an exchanger which has the DHW flowing through it.
This then heats the hot water to the tap quickly.

Obviously, if the flakes are blocking the flow of water through the
rads side of the heat exchanger, then there is not as great a transfer
of heat to the DHW.

Hope I have explained that clearly.
Rob