Rheem Water Heater Smells Like Gas? Leave

The Short Answer: Rotten-egg odor at a Rheem, Ruud, or Richmond tank is mercaptan until a utility or licensed fitter says otherwise. Leave. Call the gas company from outside. Do not soap the flex, snug the control, or keep lighting the pilot. Sulfur only at the hot faucet is an anode, not this emergency. Tankless Rheem is a different box.

Search Intent & The Real Problem

You opened the closet on a glass-lined Rheem and the room smelled like a matchbook. Or it only stinks when the main burner opens. People call that “normal gas-heater smell.” A clean burner should not put mercaptan in the laundry. Rheem, Ruud, and Richmond share Honeywell / Resideo gas controls, FVIR screens, and the same 3/4-inch flex mistakes. A whoosh at light-off is delayed ignition dumping unburned fuel, then the next spark.

Tankless cousin: Rheem tankless gas smell. Generic closet: closet smells like gas. Odor only on a heat call: when it turns on. After a lighting card: after lighting. This page is a tank Rheem / Ruud / Richmond.

What other guides get wrong

They tell you to mix dish soap and crawl a Rheem closet that already smells. They recommend “checking the pilot” and airing it out with the heater still piped. They confuse sulfur in hot water (anode + bacteria) with mercaptan in the air. They paste Paloma tankless 11/12 steps onto a standing-pilot Performance tank. And they still describe cracking the union. Do not purge it.

Step-by-Step Troubleshooting

Step 1: If indoor air smells like gas — you are done

• What to look for: Rotten-egg odor in the closet, garage, or laundry when the Rheem sits or fires. Hissing. Headache. Kids in the house.
• Required tools: Your feet, a phone outside, the utility emergency number.

Evacuate. Do not operate the heater, furnace, lights, or the garage door opener. The utility shuts the meter. A plumber leak-tests after the line is safe. Wet control after this scare is still leave-first — control box leaking gas.

Step 2: Name where the odor is — air vs water vs light-off

• What to look for: Indoor vs garage. Idle vs firing. Cold water vs air. Soot at the draft hood. A combustion door sitting crooked.
• Required tools: None on the gas train.

Need it off while you wait? Apartment shutoff. White vapor on a 20 F morning is often steam — white smoke.

Step 3: What you may look at without touching gas joints

• What to look for: From a clean-air doorway after the utility, or after odor is gone: appliance shutoff handle position (perpendicular = closed). Flex rusted, kinked, or 1/2” on a 40k-plus burner. Missing sediment trap. Lint packed in the FVIR arrestor. Paint cans or a mower in the same closet. Water in the burner tray — shut the gas; that tank is done and it is a carbon monoxide problem if you keep firing it. Jacket wet: bottom leak.
• Required tools: Flashlight, rating plate (BTU/hr, NG vs LP, Rheem / Ruud / Richmond). No wrenches. No dish soap in an occupied house that smelled.

A starving burner lights late and smells. Typical manifold is about 3.5–7 in. w.c. natural gas / 10–11 in. w.c. LP — confirm the plate. That measurement is licensed. Thermocouple on a standing-pilot Rheem is often ~20–30 mV; a thermopile is hundreds of mV. You do not chase those numbers in a room that smelled.

Step 4: Lighting attempts you must not repeat through a smell

• What to look for: Photograph the status LED before you kill anything: one green flash every few seconds is often standby on a live control; multi-flash is a lockout. A bang on a late light is delayed ignition, not “air in the line” you bleed at the flare. Night after a swap: after replacement. Pilot that will not hold after the utility clears it: will not stay lit.
• Required tools: Photo of the LED and the rating plate. Hand on the cock to leave it off.

Do not hold the knob in “a little longer.” Do not bypass FVIR with a paperclip. Do not keep clicking an electronic-ignition Rheem into a dark chamber.

Step 5: What a licensed fitter actually does at a Rheem tank

• What to look for: Standing-pressure test first, then a fire test: sniff at the inlet union, flare, control, burner tube, and draft hood while it fires. Manometer against the rating plate. Combustion: stable blue, no rollout, FVIR door seated, vent attached. Millivolts if it is a standing pilot. Control-box odor after the utility is still their job — control box.
• Required tools: On their truck. Not yours.

A leak that is tight at rest and wet at fire is still a leak. Dish soap in a house that already smelled is how people stay in a filling room.

When DIY Ends: Calling a Licensed Pro

It ended the first time mercaptan tracked the Rheem closet. You may leave, call the utility, photograph an LED from a clean-air doorway, and hire a licensed plumber to leak-test at fire and check combustion. You may not soap the burner while it runs, hold the knob to “reproduce” the smell, or keep lighting through odor. Same-day licensed repair is the product. Watching it fire one more time is not.

Frequently Asked Questions

Q: Why does my Rheem water heater smell like gas? A: Mercaptan from a leak at the flex, union, or control, unburned fuel from delayed ignition, or a failed lighting trial. If the room smells, leave and call the utility. Sulfur only at the hot faucet is the anode, not this emergency.

Q: Is a gas smell around a Rheem tank normal on startup? A: No. A clean burner should not put mercaptan in the room. A brief hot-metal smell on a brand-new unit is not gas. A whoosh is delayed ignition — shut it down.

Q: My Rheem is electric and still smells like gas. Can I ignore it? A: No. An electric tank has no gas train. Rotten-egg air is still a fuel leak from something else in that space. Leave and call the utility. Rotten-egg water is a different job.