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Rheem Water Heater No Hot Water: Gas, Electric, and Tankless Diagnosis

Quick Answer

Rheem water heater not producing hot water: diagnosis depends on the type. Gas tank Rheem: check the pilot light first - if it is out, follow the relighting instructions on the side label. Electric tank Rheem: check the circuit breaker and reset button on the upper thermostat. Tankless Rheem: check the display for an error code - each code points to a specific component.

Rheem water heaters not producing hot water are diagnosed by type: gas tank, electric tank, or tankless. Gas tank Rheem: check the pilot light first. If the pilot is out, follow the relighting instructions on the front label. If the pilot won't stay lit, the thermocouple (pilot flame sensor) has failed ($10-20 part, 15-minute fix). If the pilot stays lit but water doesn't heat, the gas valve has failed ($80-150). Electric tank Rheem: check the circuit breaker first. If the breaker is on, the upper or lower heating element has failed. Rheem electric water heaters have two elements: upper heats first, lower maintains. If you get warm but not hot water, the upper element is fine but the lower element has failed. If NO hot water at all, the upper element or the upper thermostat has failed. Rheem tankless: error codes display on the front panel. The most common Rheem tankless error is a flame failure from a dirty flame rod - clean the flame rod with sandpaper.

RheemWaterheaterSeverity: mediumDifficulty: intermediate75% DIY Success
Time to Fix
10–90 min
Difficulty
intermediate
Parts Cost
—
Tools Needed
Multimeter, Screwdriver set

What Does the NO-HOT-WATER Code Mean?

Rheem 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:

Heating element failed - open circuit40%
Thermal fuse blown protecting against overtemp24%
Cycling thermostat not closing to activate heat14%
Temperature sensor giving incorrect reading to board12%
Gas ignitor failed to reach ignition temperature10%

Symptoms You May Notice

  • See symptoms in detailed guide above

Can you reset a Rheem waterheater to clear the NO-HOT-WATER code?

Unplug 60 seconds. Follow model-specific reset if available.

Tools Required for Diagnosis

MultimeterScrewdriver setFlashlight

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

1

Follow the brand-specific diagnosis in the guide above

Follow the brand-specific diagnosis in the guide above. Each brand has different components and failure points.

2

Check for error codes on the display or LED pattern

3

If basic diagnosis does not reveal the cause, run the

Frequently Asked Questions

How do I find my model number?
Check the inside of the door (front-load), inside the lid (top-load), or the back/side panel for a sticker with the model and serial number.
Is it worth repairing?
If the appliance is under 8 years old and repair is under 50% of replacement cost, repair is worthwhile. Check warranty coverage first.
Can I fix this myself?
Many repairs are DIY-friendly with basic tools. Gas appliances and sealed refrigerant systems should be serviced by professionals.

Last verified for technical accuracy on March 15, 2026