Simply Koi and More Koi

Lee, I would be really interested to know how much it cost if you don't mind, and obviously how long it has lasted....... I only want to control temp through the winter to a bare minuimum of approx 12-13 degrees so that koi are 'safe' and can still be fed........ can you share any more info at the moment ?
thanks
Carl

ps.... did you have to change boiler jets as well ?

another ps......... did you have to follow any building regs with the storage of LPG ?....... is it in a ventilated area, etc ?
thanks
Carl