On Tue, 06 Jun 2006 02:39:43 -0700, Pablo wrote:

Hi

At the moment I only have my hot water on in the house (twice a day via
the timer). I have noticed that the small expansion tank in the loft
(as opposed to the big tank) has hot, brown water in it.
Is it normal for there to be hot water in this tank?

No. Likely explanation is that water is being pumped over from the vent
pipe - sort of inverted U shape with open end over the tank. This may only
happen intermittently, when the pump first runs, or constantly (but I'd
expect you'd notice the latter). First check that the water level in the
tank is only about halfway up rather than full (bend the float valve arm
down so that it only fills up to this level, and bail out water tolower
it). Then check that the open end of the vent pipe no lower than about 1"
below the rim of the tank: if it is then check whether it's come away from
any supports meant to keep it higher and raise it if possible, otherwise
trim back the open end. However there should be a rise of a foot or so
from the top of the inverted U to the open end. The exact dimensions will
depend on the topology of your system but that's a guide. If with all
these factors correct you still get pumping over you may stop itby
lowering the speed of the pump, but that's only a workaround: you should
replumb it to avoid this situation. It may be worth going to a sealed
system (http://www.makewrite.demon.co.uk/SealedCH.html).

Since your water will be well oxygenated by now I'd put in some system
cleanser (e.g. Sentinel X400) and run that for a few days or weeks then
flush out the system and refill adding inhibitor (e.g. X100). Make sure to
bail out any crud in the header tank rather than allowing it to get drawn
into the pipework.