Eccotemp water heater troubleshooting is more diagnostics-driven than traditional tank water heaters. Tankless and POU heaters use control boards, flow sensors, and thermistors that need systematic diagnosis. Below: common symptoms with diagnostic steps.
Symptom: No hot water (electric models)
- Verify electrical supply: breaker on, correct voltage at terminals
- Check inlet screen for debris — clogged screen blocks flow sensor
- Verify flow rate is above the minimum activation threshold (typically 0.5–0.8 GPM)
- Test heating elements with multimeter (disconnect power first)
- Check control board for error LEDs or fault codes
Symptom: No hot water (gas/propane models)
- Verify propane/gas supply: tank valve open, regulator working, supply pressure in spec
- Verify pilot lit (if pilot-equipped) or igniter sparking (electronic ignition)
- Check flow rate above minimum activation
- Inspect burner for debris, spider webs, or carbon buildup
- Verify thermocouple/thermopile providing correct mV signal
Symptom: Lukewarm water
Common causes:
- Demand exceeds capacity (too many fixtures running simultaneously)
- Mineral buildup on heat exchanger reducing efficiency — descale
- Failed element on multi-element units (only some elements heating)
- Low flow triggering only partial activation
- Thermistor failure causing incorrect temperature reading
Symptom: Water too hot / scalding
- Verify setpoint temperature is correct (some Eccotemp models have multiple temp settings)
- Check for stuck modulation valve (gas models)
- Inspect flow restrictor — broken restrictors cause low flow + maximum heat
- For models with mixing valves, verify mixing valve operates correctly
Symptom: Cold water sandwich
Common with all tankless: a brief cold patch when water draws stop and restart. Caused by residual cold water in pipes. Solutions:
- Install a recirculation system to maintain hot water in pipes
- Adjust delay timer if Eccotemp model supports it
- Reduce flow rate slightly to extend per-cycle heating duration
Symptom: Error codes
Eccotemp models display error codes via LCD or LED patterns. Most common categories:
- Flow sensor errors: sensor clogged or failed; clean inlet screen or replace sensor
- Temperature sensor (thermistor) errors: sensor open or shorted; replace thermistor
- Element failure errors: open circuit on one or more elements; test with multimeter
- Lockout errors: excessive faults trigger safety lockout; reset via Eccotemp reset procedure
- Ignition errors: gas/propane models — check pilot, flame sensor, igniter
Refer to your specific Eccotemp model's error code reference for exact code meanings.
Symptom: Banging or popping during heating
Usually indicates mineral buildup creating localized boiling pockets. Descale immediately.
Symptom: Water won't stop flowing / continuous operation
Stuck flow sensor or check valve. Cycle power off/on; if persists, inspect flow sensor for debris or failure.
When to call Eccotemp service
Heat exchanger replacement, control board failure, refrigerant or modulation issues on commercial units, or any error code that persists after standard reset procedures. Eccotemp authorized service technicians have specific training and diagnostic tools.