why are half of my rads staying cold?

hi, your problem looks like the pump and the system is heating the up stairs due to gravaty flow ie the hot water rises to the up stairsand not being pumped it will not complete the circulation.to check this you can bleed the down stairs cold rad or drain some water out from the lowest drain point and it should start to warm up the pipes that are cold, if its a combe tyoe boiler make sure you maintain at all times while doing this test at least 1 bar pressure ie keep it topped up with water this is very important,you need to drain quite a lot of water off to create a return flow of water in the system so passing the hot water from up stairs to the rads down stairs, hope you get the idea be carefull and you will prove the system ie if the pump is not doing its job. bobby rob.do not play with the gas [bang]!

bobby rob
May 2006