LOL @ Hutch...plumbers and wiring... [Linked Image]

I am not a plumber but am involved in alot of mechanics as well as electrics...incl "fluid technology" ( a very pompous term for the ability to fathom out hydraulics and compressed air - but does include heating and water systems too occasionally! ).

I suspect Hutch has hit it; the coil in the cylinder has failed and the water from the primary and secondary circuits is mixing. This has dangers for those using the domestic hot water - as well as potentially ruining the heating system/boiler if the primary coil and heating circuits are mixed. I strongly advise a plumber does a system pressure check, possibly a dye test. Alternatively, if the cylinder has already leaked, you just bite the bullet and change it ( saves test costs! ). Pound to a penny; if it has leaked once it will leak again - and that will happen on the first night you are away for a week! [Linked Image]

I'm guessing you're in a soft water area; notorious for eating away at copper...

[This message has been edited by uksparky (edited 10-02-2004).]

If hindsight were foresight, we'd all be millionaires!