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Blowdown Malfunction — TDS Concentration Buildup

Likely causes

Blowdown motorized valve failure — faulty electrical signal or seized actuator

Check: Measure on-site TDS (conductivity) — above 1500 μS/cm confirms blowdown malfunction; force-open test on blowdown motorized valve

What to do: Immediately perform manual blowdown → if force-open fails, replace valve/actuator → reset TDS setpoint to 1000–1500 μS/cm

TDS controller (conductivity sensor) malfunction or sensor fouled with scale

Check: Remove conductivity sensor → visually check for surface scale; calibration test with 1413 μS/cm standard solution

What to do: Remove sensor scale then calibrate with 1413 μS/cm standard solution → replace sensor if error >±5% → perform manual blowdown at least 3 times per week

Field tip

TDS 1500 μS/cm equals ~4× concentration ratio — above this level, scale, corrosion, and Legionella risks all rise simultaneously.

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