Why I concerned on performance of heat pipe that my builing’s FAHU, some FAHU are above 230 ton, in our buildings most of which equipped with heat pipe. The cooling coil are trapped with heat pipe and is very difficult to service the coil. The annual maintenance contractors were reluctant to service the unit because of the difficult to remove the heat pipe which rivetted around the coil and very congested between the walls. But all buildings are experiencing serious fresh air issues and humidity, so we decided to remove the heat pipes, some cut the pipe and some removed from the housing. Some FAHU was totally dismantled and took out the coil. It was totally blocked the coil. Now some local contractors proposed heat pipes of easy removal type and they submitted the data sheet. The manufacturer mainly claimed that the heat pipe will reduce the rows, in design, of cooling coil and will maintain relative humidity. So, I put in psychometric, I found very small changes in humidity content 0.1 g/kg only. this same digit is aligning with other manufactures also when comparing.