Ground Loop Flow Reduction — Air Entrainment / Cavitation

Question

Accepted Answer

Air pocket at high point in loop. Check: incomplete purging during fill What to do: Open automatic/manual air vents at high points — repeat purge until flow meter stabilizes Expansion tank pressure insufficient or bladder failed. Check: system pressure drops below 0.5 bar What to do: Check expansion tank nitrogen pre-charge pressure (normally 1.5~2.0 bar); recharge or replace if needed Circulation pump impeller worn. Check: flow more than 20% below design What to do: Measure pump current and flow rate — replace impeller or pump if more than 20% below rated Filter/strainer clogged. Check: Inspect with instruments or visually What to do: Disassemble and clean strainer — recommend inspection every 6 months Underground pipe partially crushed or ground settlement. Check: Inspect with instruments or visually What to do: Pressure-test underground piping at 1.5× operating pressure — check for leaks and crushing

Ground Loop Flow Reduction — Air Entrainment / Cavitation

Likely causes

Air pocket at high point in loop

Expansion tank pressure insufficient or bladder failed

Circulation pump impeller worn

Filter/strainer clogged

Underground pipe partially crushed or ground settlement

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