Two simple questions steam

Snowmelt

1. When there’s a tee after the header then splitting in two different direction why do we want to get rid of that tee an put two tees on the manifold.
   
   2. When buying black pipe fittings why do we want malleable for steam but not gas ?

clammy

Usually these are split due each one being a separate steam and the single pipe feeding them cannot properly support the connected edr. There is no mailable for steam it’s either mailable or cast iron either may be used but most who do it right just use cast iron .
peace and good luck clammy

EBEBRATT-Ed

Malleable fitting can be used on steam and gas. Cast iron cannot be used on gas but can be used on steam and hot water heat