Under pressure, one psi will raise water 2.3 ft. It doesn't matter if it's
Buffalo NY or Death Valley CA. The average 3rd story radiator is less than
30 ft. above the boiler, and needs no more than 13 psi. If you need 25 psi
to heat the 3rd floor radiators, they must be about 57.5 ft. above the
boiler.

"buffalobill" wrote in message
oups.com...
at 15 greenfield, buffalo ny altitude we need 25 pounds WHEN HOT AND
CIRCULATING to get from the basement to the third floor hot water
boiler radiators. our temperature is set to max at 180 but it depends
on your system. our expansion tank has no bladder and we set it to half
water half air when cold. you must refer to installation manuals on all
parts of your system.