Hot Water

[Jeffro]

I have just had a new central heating system fitted (combi boiler) so why is my hot water `milky`

[shylock73]

It`s very probably that the water is hard in your area and its the lime in it. If it clears after a few moments that is the reason, nothing to worry about tho except a build-up of lime in the kettle. This can be easily removed with 1-1 white vinegar and water left overnight or a propriety kettle cleaner.

[heathfield]

Water has air dissolved in it. When you run the tap, the pressure that the water is under in the mains supply is suddenly reduced. This has the same effect as when you open a bottle of lemonade - bubbles appear. The milkiness is actually tiny bubbles which will disappear as you let the water stand.
Cold water is able to hold more air dissolved in it than hot water can, so you don't see this effect when you run the cold tap.
But when the water is heated in your combi boiler, it tries to release some of the air, but still being under pressure, it can't, until you turn on the hot tap
It's totally harmless.

[webdude]

Combi boilers are sealed systems i.e. they are at mains pressure and not fed by gravity from a tank in the loft.

I have a Mega Flow which works on the same basic principle, and often my hot water appears milky when the tap is run. This is quite normal and can ocurr when the tank refills and the pressure of the incoming water causes minute air bubles to form in the tank.

[squarebear]

Ours too does this. Just run it for a few minutes and it soon clears.

[Jeffro]

Thanks everyone