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.

Thanks,
Vince.