central heating

[manny]

i have changed my heating system from a open system to a combi system and the plumper took away the hot water storage tank and linked out all the pipework No problem. Since then i have converted my loft and installed a radiator up there .the problem is where the diverter valve was there a 4 pipes that look like flow and return linked out and i have traced them back and they go into the flow and return manifolds . teed of each pipe and plumbed each one to the radiator in the loft.i am getting a hot flow but looks like i am getting no return i have bleed the radiator but still no joy can any body help. :(