"MarkM" wrote in message
om...
"BillR" wrote in message
...
Vince wrote:
We've had a combi-boiler fitted, early this year, to drive the heating
and hot water. It seems to be working fine at the moment. The thing
is though that the hot water comes out white and it takes a few
seconds in the sink before it clears.
I know it's only miniscule air bubbles in the water and that they're
harmless in themselves. The question is, what is causing the bubbles
to be present in the water and is it inticative of any possible
problems in the system?
I've had a good check around over the last few weeks and can't find
any sign of leakage.
Thinking about it (though it's probably unconnected) - the central
heating does not have a header tank but is fed from the mains via a
valve. I check the central heating pressure periodically and let more
water in if the pressure drops. The thing is, the pressure does drop
so I'm having to allow a bit more water in every month. Doesn't sound
right to me but I still can't find any leaks anywhere.
Any advice on the significance (if any) of the white water or central
heating pressure drop gratefully received.
I don't think the pressure drop is anything to do with the "white"
water.
The pressure drop is concerned with the CH (radiator) side of the system
and
is due to a small leak/seepage from the radiator circuit and should be
fixed. Fernox do a leak sealer in a tube that can easily be injected
into a
rad bleed valve. This has worked well for me on two different systems
but
its not cheap.
As you say the white water could just be the heat driving out the normal
dissolved air in the incoming water but I would have thought the water
would
have had to be much hotter than is normal for a domestic HW tap.
The white bubbles in combi hot water is exactly this - dissolved air
being driven out. It's just because the water has been recently heated
from cold water rich in dissolved gas (air? oxygen?) without any time
sitting around in a tank for the bubbles to come to the surface. If
you heat a kettle of water, you can see the disolved gas coming out of
solution long before boiling point.
You can see this with some taps, especially aerated taps.
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