Originally Posted by Dunccoss
doug is it a sealed system because if it is forget what i said in my post above
No it has a black plastic tank that is issulated (approx 18" wide x 15" high x 12" front to back) The tank has no water supply too it because I did not want mains water in the roof space, so I top up/check level of the tank at least twice a year. It normally needs about couple of litres of topping up per year thats all. No leaks anywhere it's just evaoration I'm 98% sure.