Blue water in Brum a bad sign ...

[Chris Bartram]

Not usually IIRC, which is why you're supposed to close the taps either end.

[Brian Gaff]

Interestingly, in Guernsey some years ago when certain soaps were used in their water it turned bright blue. It was tested and found to be perfectly safe and the strange effects were blamed on trace minerals in the bore holes where a lot of people got their water. It apparently did not affect water from their main supply, which was a flooded valley, and mostly from rainwater. Nobody has died and I quite liked the taste of the bore hole very soft water. Brian

[Robin]

...*and* disconnect at least one end of the loop. And AIUI that still applies even though (I think) the regs. do now mandate a DCV.

Of course most people know that the risk of the water police breaking the door down at dawn to check non-compliance.

[GB]

So I'll just have to remember not to try to top up our central heating system when the mains pressure is nil. Who'd have thought that's a bad idea? ;)

[Roger Hayter]

My understanding was that both ends should be disconnected! Apart from back-siphonage there is also the risk of increasing the pressure in the CH system to mains water pressure if there is a slow leak through the valves and this could be especially harmful a) if it is high and b) if done when the system is cold.

AMI my 20 year old Firebird oil boiler has a non-return valve on the boiler end valve fed from the loop. I don't know if this is general. But it is a very good idea if one opens the valve with no filling loop in place and the boiler hot.

[John Rumm]

Its an increasingly uncommon way of doing it these days. Many properties will have mains fed cold all to all points of use in the house.

[John Rumm]

A (proper) filling loop includes a double check valve on the inlet of the CH pipework, such that its impossible for water to escape from it.

[Robin]

Anglian Water reported a case a few years ago where the impossible (allegedly) happened :) Warm water (with inhibitor!) from the CH was going into the supply after the taps on the loop weren't turned off properly and the DCV let by.

Found when the customer complained about funny tasting water!

[David]

O.K.

(1) The water has been off.

(2) During that time you have run a cold water tap and eventually got blue water.

(2a) If your system is tank fed then you have run off a lot of cold water which you shouldn't have been drinking in the first place.

(3) The water is back on.

So flush the toilet and run the cold tap for 30 seconds.

Still getting blue water?

Talk to your supplier.

Cheers

Dave R

[John Rumm]

Tis why you are supposed to disconnect the flexi hose as well. ;-)

(although you can't do that if you have a combi with an internal filling loop like many of the WB and Vaillant models).

[GB]

Why both ends?

[Capitol]

I didn't know you lived near me!