Rheem Rheem Professional Classic 50 Gal. 38,000 BTU Natural Gas Water Heater RUMBLING Error Fix: Rumbling or Popping Noises During Heating

Error code RUMBLING on the Rheem Rheem Professional Classic 50 Gal. 38,000 BTU Natural Gas Water Heater means: Rumbling or Popping Noises During Heating. The water heater makes rumbling, popping, crackling, or banging noises during heating cycles. This is caused by sediment (calcium carbonate and minerals) that has settled at the bottom of the tank over time. When the gas burner fires, it heats the sediment layer from below. Water trapped under the sediment turns to steam, creating popping and rumbling sounds as bubbles escape through the sediment. This is not immediately dangerous but indicates significant sediment buildup that reduces efficiency, shortens tank life, and can clog the drain valve. Flush the tank to remove sediment. If the tank has never been flushed, the sediment may be too hardite to drain — a full tank cleanout may require removing the drain valve to break up and remove compacted sediment.

The most successful fix is "Remove and Replace the Drain Valve to Clear Compacted Sediment" (medium difficulty, ~60 minutes). Estimated DIY cost: $15-$30. HomeMD has 2 community-ranked fixes for this error.

This error is rated info severity. It is generally not urgent and can often be resolved with a simple DIY fix.

Yes — the top-ranked community fix ("Remove and Replace the Drain Valve to Clear Compacted Sediment") is rated medium difficulty and takes about 60 minutes. Tools needed: Adjustable wrench, Plumber’s snake, Wire brush, Teflon plumber’s tape.

DIY cost: $15-$30. Professional repair typically costs $150-$250. Many homeowners save money by trying the top-ranked community fix first.

The Rheem Rheem Professional Classic 50 Gal. 38,000 BTU Natural Gas Water Heater has 8 other known error codes, including: 1 BLINK / 3 SEC (Normal Operation), 2 FLASH (Thermopile Voltage Low), 4 FLASH (Temperature Exceeded High Limit), 5 FLASH (Temperature Sensor Failure), 7 FLASH (Gas Control Valve Electronics Failure), and 3 more.

Error code RUMBLING also appears on 1 other Rheem model: Rheem Performance 40 Gal. 4500-Watt 6-Year Tank Electric Water Heater. The fix may vary by model, so check each model's specific page for tailored repair steps.