hot water radiators

computergranny

I live in a ranch home with a 44 yr. old hot water heating system. The upstairs is baseboard heating copper pipe fins. The basement has 2 cast iron upright radiators. For 44 yrs., the basement has been warm as toast. This year the radiators in the basement are stone cold not producing any heat.

Bled air off without correcting the problem. When I trying to get air out the system, with the motor running, the inlet and outlet pipes are hot to the touch. However the radiator itself remains cold without producing heat.

Tried bleeding system with the pump not running, appears to be no air in the system.

Suggestions appreciated.

undone

How would you know if the pump is running? An overheating pump will make the inlet and outlet pipes appear warm without actually moving water. Are there any mixing valves you may not have taken into account?
Also, depending on where the basement heater takes off of the primary loop, the basement loop can be deprived due to a prior take off if its demanding.

biggles

could be the return from those 2 radiators if they are in series and back to the boiler,is the run to the basement off the pump or part of the entire system up to the upstairs