Water Heater No Hot Water: Gas vs Electric vs Tankless Diagnosis
Quick Answer
Water heater no hot water - diagnosis by type. GAS TANK: check pilot light first. If out, relight per instructions on tank label. If pilot won't stay lit, thermocouple failed ($10-20, 15-min fix). If pilot stays lit but water cold, gas valve failed ($80-150). ELECTRIC TANK: check breaker (dedicated 240V circuit). If breaker on, upper heating element or thermostat failed. Warm but not hot = lower element failed.
Water heater no hot water - diagnosis by type. GAS TANK: check pilot light first. If out, relight per instructions on tank label. If pilot won't stay lit, thermocouple failed ($10-20, 15-min fix). If pilot stays lit but water cold, gas valve failed ($80-150). ELECTRIC TANK: check breaker (dedicated 240V circuit). If breaker on, upper heating element or thermostat failed. Warm but not hot = lower element failed. No hot water at all = upper element/thermostat. TANKLESS: check error code on display. Most common: ignition failure (clean flame rod), flow sensor minimum not met (low-flow fixtures), or scale buildup (descale with vinegar). ALL TYPES: check hot water usage - did someone take a long shower before you? Tank water heaters take 30-60 minutes to reheat.
What Does the NO-HOT-WATER Code Mean?
No hot water: GAS=check pilot light, relight or replace thermocouple ($10-20).
Most Likely Causes
Based on aggregated repair data, here is the probability breakdown for this error code:
Symptoms You May Notice
- Water Heater No Hot Water: Gas vs Electric vs Tankless Diagnosis
Can you reset a Generic waterheater to clear the NO-HOT-WATER code?
Unplug 60 sec.
Tools Required for Diagnosis
Diagnostic Checklist
Follow these steps in order. We start with the easiest external fixes before opening up the machine.
Follow guide above.
Follow guide above.
Check error codes.
Professional if needed.
Frequently Asked Questions
Cost?
DIY?
Worth it?
Last verified for technical accuracy on March 15, 2026