Display shows “LO” and the unit will not start or shuts down shortly after starting.

Safety first: Turn off power at the main breaker and verify with a meter that power is off before touching any wiring.

• Inspect supply wiring: Remove the electrical access cover. Check that the incoming power wires are tight on the terminal block or contactor lugs. Look for discoloration or melted insulation.
• Measure voltage: With a multimeter and power restored, measure line voltage at the heater’s input. Compare to the nameplate rating (e.g., 208/230V). Voltage more than ~10% below rating can cause LO errors.
• Tighten connections: Turn power back off and tighten any loose lugs to manufacturer torque specs. Replace any burned or damaged connectors.
• Check breaker and wire size: Confirm the breaker and wire gauge match Heat Siphon installation requirements. Undersized wiring can cause voltage drop under load.
• If voltage is consistently low: Contact an electrician or your utility provider. Do not operate the heater with low voltage, as it can damage the compressor and electronics.