National Oilheat Research Alliance 17
4. Counterflow system
• With this system steam and condensate flow “counter to” (against) each other in the
steam main.
• Steam MUST enter the top of the steam main to keep condensate from flowing back
into the top of the boiler.
• The supply main must maintain a minimum of 1" per 10' pitch upwards towards the
return to prevent condensate from causing water hammer. The preferred pitch is 1/4" per ft.
• A Hartford loop is NOT required because the return is above the boiler water line.
• No return riser is needed because the condensate flows back to the to the equalizer piping.
• Dimension “A” must only be 14" because there is no wet return and very little pressure drop
from the boiler to the point of condensate return.