Some help would be appreciated. My central heating system makes a wining noise at start up then eventialy goes away and sometimes doesnt.It has been doing this wining noise for the last few years and I have lived with it up untill now. I`m selling the property and need to get it sorted. I`m not the best plumber around but I do give general plumbing a go. What could be the cause of the wining noise. The system is a vented system with a seperate cistern in the loft for the cold water supply and a heating cistern supply. Some radiators have TRV`s fitted but are very old. I will be replacing these anyway. While the TRV`s are out I`ll also flush out the rads. Any suggestions would be appreciated.