NTI GF 200 - Troubleshooting: Fan Not Running

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4.6 Troubleshooting
E.438 – Abnormal circulation pump
о Error description:
◊ Incongruity between Pump activation signal and Flow Sensor reading.
о Potential causes:
◊ Air-lock
• During commissioning, the rst Central Heat call may introduce air into the pump, which can overwhelm
the impeller and induce air-lock.
◊ Faulty Flow Sensor or Pump
• It is possible that the pump is failing to generate any ow, or that the sensor is failing to read it.
о Troubleshooting:
◊ If air-lock is suspected (when error appears during Central Heating):
• Ensure that the air eliminator on top of the pump housing is open.
• Flood the pump chamber by opening the valve between it and the Buer Tank (set it to 'INT')
• Press Reset button (bottom left) to clear the error code and resume Central Heating (if call still active).
• Once the pump resumes operation, air should begin escaping from the eliminator.
• Slowly close the valve by the valve by setting it back to 'EXT'. Air should continue to escape.
• If E.438 re-appears, repeat this procedure. If the air-lock does not clear after 3 attempts, check inlet
water supply (and pressure), and attempt a Central Heat call with a simultaneous DHW draw (~ 2 GPM).
◊ Otherwise:
◊ Check Flow Sensor:
• Get back to Stand-by mode (i.e. stop heating (‘W’) call).
• Apply a DHW draw and observe the ow sensor’s output.
• Press Info button (middle left), then [ – ] to see the current ow rate (GPM).
• If readout corresponds to expected ow rate value (based on visible water ow at the xture), we can
eliminate the Flow Sensor as the root of the error.
◊ Check that brass isolation valve is open
• Make sure the black plastic handle is parallel to the valve body and piping
◊ Perform a Pump Test
• From Stand-by, press and hold Diagnostics button (top left) for 5 seconds to enter Test mode
• Press Info button to enter Test menu, and use [ + ] and [ – ] buttons to scroll to “Pump”.
• Press Info button to start the test (5-10 seconds on/o cycles for 1 minute)
• Observe display readout  it should cycle between “On” / “O” and “_ . _” GPM
If these steps fail to resolve the error, contact NTI Technical Support for further assistance.