Heating - Variable Speed Pump
If the pump is for potable water then buy the stainless steel version because potable water is oxygenated. Only in the case of a closed radiant heating system with oxygen barrier PEX is it ok to use the cast iron version.
008 Variable Speed Delta-T Stainless Steel Circulator Pump, 1/25 HP
Cast iron version
008 Variable Speed Delta-T Cast Iron Circulator Pump, 1/25 HP
Pump Flanges (Stainless)
Pump Flanges (Iron)