Thanks for all the replies. I've tried running it on a setting of 25
degrees Clarke (I got this number from a neighbour). It shows "r0" on
the display for a couple of minutes and water is continuously venting
down the waste pipe.

However, it continues to vent water and the display changes to "E2" -
which sounds like an error to me. I let this carry on for a further ten
minutes with no change. I gave up and turned it off.

One clue - water vents down the waste pipe even when the unit is not
switched on... a valve stuck open perhaps?

I've been trying all day to get through to their helpline but it's
constantly engaged and ringback doesn't seem to work. Perhaps they have
it off the hook!

Anyone know what this "E2" business is about?

Thanks

Nick