the site 51 comprises a buffer tank 53 located intermediate the energy conversion system 5 and the heated sheds 3 4 a pump 55 is provided to pump water from the buffer tank 53 back to the energy conversion system 5 a pump 57 is provided to pump water back from the indirect heaters 9 in the first poultry shed 3 and a pump 59 is provided to pump water back from the indirect heaters 9 in the second poultry shed 3 4 the energy conversion system operates to keep the liquid in this case water in the buffer tank at a uniform temperature preferably 85 u00b0 c the energy conversion system thermally treats poultry litter and harnesses the heat from the burning of the poultry litter to heat water which is passed to the buffer tank the hot water in the buffer tank 53 is then delivered to the radiator elements of the indirect heaters 9 in the sheds 3 4 and returned to the buffer tank 53 where it may then be returned to the energy conversion system for re heating various hydronic manifolds may be provided to ensure that the flow and the return water is kept as separate as possible to prevent thermal siphoning of the heat in the water and to ensure that the hottest water is delivered to the indirect heaters 9 and the coldest water is returned to the energy conversion system 5 referring to fig6 there is shown an energy conversion system indicated generally by the reference.