upgrade circulator pump in closed hot water heating system?
The Maximum head of the pump is not to push the water up to the radiators, it is to overcome the friction loss of the flow of the water in the system. The installed pump should be large enough for your heating system. The water in the system is held up to the highest radiator by the water pressure in the system (look at the pressure gauge mounted somewhere on the boiler) A rule of thumb is 12 psig for a 1 story house, 15 psig. for a 2 story house and 20 psig for a 3 story house. Turn the boiler system off, go to the highest rad and open the vent. If you get water out then the pressure on the boiler is okay.If you can't get the temperature high enough check for water in the rads or baseboard units, vent all the air that may be in the heating elements. If all this fails call a boiler co. to fix the problem. One more thing, if you screw up and install too large of a pump you will get noise in the piping or radiation.