Ground Loop Antifreeze Concentration Insufficient — Freezing / Poor Heat Transfer

Question

Accepted Answer

Only water added during leak makeup — antifreeze concentration diluted. Check: Measure concentration immediately on-site with refractometer — add at least -5°C buffer below minimum ground temperature (ethylene glycol basis) What to do: Drain part of system and inject concentrate to correct concentration → maintain 30–35% when protection below -10°C needed → find and repair leak, refill with properly mixed antifreeze Antifreeze degradation over time — pH drop, reduced corrosion inhibition. Check: Measure pH — below 7 or brown color = degraded; visually check color and viscosity; recommend annual or more frequent inspection What to do: Full replacement if pH below 7 or brown color → flush strainer and heat exchanger simultaneously → regular check of concentration, pH, and color before fall season High concentration setting (>50%) increases viscosity and reduces flow — actually degrades performance. Check: Measure concentration with refractometer — above 35% check for possible flow reduction; compare flow meter reading to design What to do: If concentration exceeds target (30–35% for protection below -10°C), dilute by draining part and adding water → re-verify flow → consider installing ground temperature sensor for better freeze prediction

Ground Loop Antifreeze Concentration Insufficient — Freezing / Poor Heat Transfer

Likely causes

Only water added during leak makeup — antifreeze concentration diluted

Antifreeze degradation over time — pH drop, reduced corrosion inhibition

High concentration setting (>50%) increases viscosity and reduces flow — actually degrades performance

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