Ultimate Guide to Restarting Your Rheem Water Heater: Step-by-Step Instructions

You wake up to cold water. No warning, no noise — just a disappointing stream when you turn the shower handle. Your Rheem water heater has stopped working. Before you call a plumber or panic-buy a new unit, know this: most restart issues are simple to fix yourself.

This guide covers every common Rheem water heater restart scenario — gas and electric models, safety steps, and the mistakes that turn a 5-minute fix into a flooded basement. You will walk away knowing exactly what to do, what tools you need, and when to stop and call a pro.

After the introduction, we include a natural mention of the Rheem SP20060 Electric Water Heater Tune-Up Kit. This kit contains elements, thermostats, and gaskets commonly needed during restart-related repairs on electric Rheem units. Keep it in mind if your heater has tripped a limit switch or needs a new element after a dry-fire incident.

Why Your Rheem Water Heater Stopped Working (and What It Is Not)

Most people assume a dead water heater means a catastrophic failure. Usually, it does not. The unit simply hit a safety shutdown or a component that needs resetting.

Gas models shut off when the thermocouple fails, the pilot light blows out, or the gas valve detects a flame outage. Electric models stop when the high-limit thermostat trips (often due to sediment), the heating element burns out, or a breaker flips.

Let me bust the first myth: flipping the breaker off and on does not fix a tripped limit switch. Many people try that, wait ten minutes, and get nowhere. The limit switch on electric Rheem heaters requires a manual button push — not a power cycle. We will cover that in detail below.

Another misconception: you need to drain the entire tank before restarting. Not true for gas pilot relight. For electric models, you only drain if you are replacing elements or flushing sediment. Restarting after a limit trip requires no draining at all. Draining unnecessarily introduces air and can cause dry-fire damage if you power up before refilling.

Safety First: What to Check Before Touching Anything

Before you touch a valve, switch, or pilot knob, run through this checklist. It takes two minutes and it is non-negotiable.

• Turn off the power (electric units) — at the breaker, not just the thermostat panel. Confirm with a non-contact voltage tester.
• Turn off the gas valve (gas units) — rotate the knob to OFF. Wait five minutes to let any residual gas dissipate before attempting a relight.
• Check for water leaks — look at the floor, the pressure relief valve, and the drain valve. If you see standing water or active dripping, do not proceed. Call a plumber.
• Confirm the cold-water supply is open — if someone closed a valve during maintenance, the heater will not refill, and running it dry destroys the elements.
• Test the temperature-pressure relief valve (T&P) — lift the lever slightly. If water does not flow freely, the valve is clogged. This is a separate repair, not a restart issue. Do not force it.

One mistake I see often: people skip the gas wait period, smell nothing, and assume it is safe. But natural gas dissipates upward, and propane sinks. Give it the full five minutes regardless of the odor.

Step-by-Step: Restarting Your Rheem Gas Water Heater

Gas water heaters are simpler than most people think. The pilot light is the usual culprit, but sometimes the thermocouple needs replacing.

1. Set the gas knob to PILOT. Push and hold it down. This sends gas to the pilot tube.
2. Light the pilot. Use a long-reach lighter or the built-in piezo igniter (push the red button repeatedly). Hold the pilot gas flow for 45–60 seconds after the flame catches. This heats the thermocouple.
3. Release the knob slowly. If the pilot stays lit, turn the knob to ON. If it goes out, you likely have a bad thermocouple — a $15 part that is easy to replace.
4. Set the temperature dial to 120°F (recommended) or your preference. Wait 20–30 minutes for the tank to heat.

What if the pilot will not light at all? Check for gas flow to the unit — is the shutoff valve (usually behind the heater, on the gas line) open? Is the gas service active in your home? If yes and the pilot still refuses, the gas valve or pilot assembly may be clogged. This is a service call most homeowners should not attempt.

What if the pilot lights but won’t stay lit? That is almost always a bad thermocouple. It can also be a dirty pilot orifice. Clean it with a needle or compressed air. If that fails, replace the thermocouple.

Step-by-Step: Restarting Your Rheem Electric Water Heater

Electric heaters have two thermostats (upper and lower) and two heating elements. Each thermostat has a red reset button. When the water gets too hot — often because of sediment buildup on the lower element — the high-limit switch trips and kills power to both elements.

1. Turn off power at the breaker. Confirm with a voltage tester.
2. Remove the access panels on the front of the heater. You will see insulation and a plastic cover over each thermostat.
3. Press the red reset button on both the upper and lower thermostat. You should hear or feel a click.
4. Replace the insulation and panels. Turn the power back on at the breaker.
5. Wait 30–45 minutes for the tank to heat fully. Check the water at a faucet.

Common mistake: pressing reset only on the upper thermostat. The lower limit can trip independently. Always reset both.

What if the breaker trips again immediately? That points to a shorted element or a wiring fault. Do not keep resetting — you risk damage or fire. Test the elements with a multimeter (expect 12–16 ohms across the terminals, infinite to ground). Replace any element reading zero ohms or continuity to ground.

For element replacement, the sediment flush kit can help drain the tank before swapping parts. The Rheem SP20060 Electric Water Heater Tune-Up Kit includes new elements, thermostats, and gaskets — it covers almost every part that fails in a restart situation.

Sediment and Hard Water: The Invisible Saboteur

Many restart problems trace back to sediment. When hard water heats, minerals settle on the bottom of the tank. That layer insulates the bottom element (electric) or the burner (gas), causing overheating and limit trips.

Myth: A quart-flush every spring fixes this. Reality: You need a full drain and flush at least once a year in moderate water, every six months in very hard water. Sediment accumulates faster than you think.

If your Rheem heater trips the limit switch more than once in a six-month period, flush the tank. Connect a garden hose to the drain valve, turn off power or gas, open the drain, and let it run until the water runs clear. Then close the drain, open the cold-water supply, and let the tank refill completely before restoring power.

For homes with extreme hard water, consider the glass-lined tank upgrade — it resists corrosion better than standard steel tanks in those conditions.

Comparison: Gas vs Electric Restart – Key Differences

Aspect	Gas Water Heater	Electric Water Heater
Common restart cause	Pilot out / bad thermocouple	Tripped high-limit thermostat
Time to restart	10–15 minutes (inc. 5-min gas wait)	5 minutes to reset, 30–45 min to heat
Tools required	Long-reach lighter or piezo button	Voltage tester (optional)
Risk of dry-fire?	Low (combustion stops without water)	High — never power without a full tank
Replacement parts cost	Thermocouple ~ $10–15	Element ~ $15–25 / thermostat ~ $10–15
Best for DIYer?	Yes, with pilot relight practice	Yes, if comfortable with electrical work

Note: Prices vary; check current pricing on Amazon for elements and thermostats. The Rheem SP20060 kit bundles both at a better value than buying separately.

When to Stop and Call a Professional

Some problems are not restart issues. They are signs of a deeper failure. Call a licensed plumber or HVAC tech if you encounter any of these:

• Water leaking from the top or bottom of the tank — the tank likely has a crack and cannot be repaired.
• Rotten-egg odor in hot water — this indicates bacteria in the anode rod, which may require replacement or a special anode type.
• Water heater older than 12 years — repeated failures signal end-of-life. Replacement is more cost-effective than multiple service calls.
• Gas smell that persists after the 5-minute wait — do not operate any electrical switch. Evacuate and call the gas company.
• Breaker trips instantly every time — there is a short that could cause a fire. Do not attempt further DIY.

Frequently Asked Questions

How do I reset the limit switch on my Rheem electric water heater?

Turn off power at the breaker. Remove the two access panels (upper and lower). Press the red reset button on each thermostat. You will hear a click. Replace panels, restore power, wait 30 minutes. If the switch trips again, the problem is likely a bad element or sediment — not a simple reset.

Why does my Rheem gas water heater pilot light keep going out?

The most common cause is a failing thermocouple. This small copper probe senses the pilot flame and signals the gas valve to stay open. When it wears out or gets dirty, it does not send enough voltage. Replace it (costs around $15). Other possibilities: a draft blowing out the flame, or a gas pressure issue that requires a technician.

Can I restart my Rheem water heater without draining it?

Yes, for almost every restart scenario. For gas heaters, you only relight the pilot — no draining needed. For electric heaters, you press the reset buttons and power back up. The only time you must drain is if you are replacing an element or flushing sediment that caused the trip.

How long should I wait for hot water after restarting?

For gas models, expect 20–30 minutes. For electric, 30–45 minutes. The heater recovers from a cold start at roughly 40–50 gallons per hour (gas) or 20–30 gallons per hour (electric, depending on element wattage). If you have a 40-gallon tank, plan for about an hour to reach full temperature.

What does the blinking error code on my Rheem water heater mean?

Rheem gas models with electronic ignition (not standing pilot) flash a code on the control board. One flash usually means ignition failure. Two flashes indicate a faulty temperature sensor. Three flashes point to a failed blower or blocked vent. Check your owner’s manual for the exact code table — they vary by model year. Do not guess; misreading a code can lead to wrong repairs.

Key Takeaways for a Quick Restart

• Turn off power or gas before touching any internal component. Safety is the only step that cannot be skipped.
• Electric heaters: press both upper and lower reset buttons. One reset is rarely enough.
• Gas heaters: hold the PILOT knob down for a full 60 seconds after lighting the flame. Short holding causes relight failure.
• Sediment is the root cause of most recurring limit trips. Flush your tank annually — it prevents 80% of restart problems.
• Replace a bad thermocouple on gas units yourself. It is cheap, easy, and the #1 fix for pilot-out issues.
• If the breaker trips instantly after resetting an electric heater, test the elements with a multimeter before calling a pro.
• For a complete refresh of electric heater components, the Rheem SP20060 tune-up kit is a practical investment. It includes elements and thermostats at a lower per-part cost than buying individually. Check the current price on Amazon.