: I have a hot water heating system that was updated to a high efficiency system with a circulating pump. The radiator on the third floor is not getting water. The piping that goes to the third floor is a direct connection from the main pipe not more than five feet from the boiler. Any ideas?I had a simular problem that was caused by a combination of Air, system pressure and monoflo tees. Have you gotten All the air out of the system? Is the pressure somewhere between 8 and 12 psi? Where there zone valves put in during the upgrade? Here are a few things to look at first.