Sizing black pipe for radiator runs? Recommendation?

Jack M

When adding a radiator run (one pipe) off an existing main is there a recommended pipe diameter? Some of the longer existing radiator runs are 1-1/4" but most are 1-1/2". The "newer" pipes are all 1-1/4" (1.37 OD) while the older ones (1920's) are all 1-1/2" (1.9" OD).
How do you decide which size pipe to use when adding a new radiator run? Does it matter? Is the pipe diameter based on the radiator's EDR?

Abracadabra

http://forum.heatinghelp.com/discussion/154319/pipe-sizing-for-steam-radiators

http://forum.heatinghelp.com/discussion/155666/installing-a-steam-radiator-piping-size

http://forum.heatinghelp.com/discussion/129537/runout-versus-riser-size

Jack M

Abracadabra said:

http://forum.heatinghelp.com/discussion/154319/pipe-sizing-for-steam-radiators

http://forum.heatinghelp.com/discussion/155666/installing-a-steam-radiator-piping-size

http://forum.heatinghelp.com/discussion/129537/runout-versus-riser-size

Abracadabra. Just what I was looking for.