Need help! Just moved into a old house with radiator heat. There are 5 radiators upstairs but only 3 of the get hot...one gets lukewarm and the other stays cold.The one that stays cold is in the bathroom. I bled all radiators of air and made sure all the valves were open but it still gets no heat. There are only ten radiators in the house and the pump should be big enough at 1/12 hp. In the basement I found the pipe leading up to the bathroom begins hot but quickly goes down to warm and then apparently cold as it travels up thru the house. Any suggestions would be greatly appreciated.