can enyone tell me why my boiler will not heat all 7 radiators at the same time, 4 will get hot the other 3 farthest from the boiler will only get luck warm, if i turn the three nearest the boiler off ,the 4 farthest away get nice and hot but turn on all 7 again and the 3 furthest away go cool. could it be the pump?

janet2008, January 2009