How to reset a tankless water heater after a power outage
Power outage knocked out your tankless water heater? Here's how to reset it safely in Prescott, AZ - plus error codes and when to call a pro.
To reset a tankless water heater after a power outage in Prescott, turn off the unit at the breaker or power switch, wait 30 seconds, then restore power and press the reset button if your model has one. If the unit still won't fire, check for an error code on the display and clear it by holding the reset button for 5 seconds. Most outages in Prescott last 2-4 hours, and a simple reset gets hot water back in under 5 minutes. This guide walks you through the exact steps, the error codes you'll see, and when it's time to call a pro.
Why a power outage trips your tankless water heater
A tankless water heater relies on a steady flow of electricity to run its circuit board, igniter, and fan. When the power cuts out, the board loses its memory and the unit shuts down as a safety measure. When power returns, the board may not automatically restart - it waits for a manual reset or a signal from a flow sensor.
Prescott's power grid sees outages from monsoon storms in July and August, winter ice on overhead lines, and occasional planned shutoffs. In 2025, the average Prescott homeowner experienced 3-5 outages lasting 1-6 hours. Each one can leave your tankless unit in a lockout state.
Newer models from Rinnai, Navien, and Rheem often restart on their own after 10-15 minutes. Older units, or those with a faulty pressure switch, need a manual reset. If your unit is more than 10 years old, a power surge during restoration can damage the control board - that's when you need tankless water heater repair prescott in Downtown Prescott.
How do I reset my tankless water heater after a power outage in Prescott AZ?
Resetting a tankless water heater after a power outage in Prescott AZ takes four steps: kill power, wait, restore power, and press reset. Here's the sequence we use on service calls every week.
- Turn off the power. Flip the dedicated breaker for the water heater to OFF. If your unit plugs into an outlet, unplug it. Never work on a unit that's still powered.
- Wait 30 seconds. This lets the control board fully discharge. Some manufacturers recommend 60 seconds - check your manual.
- Restore power. Flip the breaker back on or plug the unit in. Listen for the fan to spin up and watch the display.
- Press the reset button. Most tankless units have a small red or black reset button near the display or behind the front cover. Press and hold for 5 seconds. The display should show a temperature or a standby light.
If the unit fires up and you get hot water within 30 seconds, you're done. If not, move to the error code section below.
For units without a reset button, turn the breaker off for 2 minutes, then back on. That hard reset clears the board's memory. If you've done this twice and still no hot water, the issue is likely a failed igniter or a tripped pressure switch - both common after a Prescott monsoon outage.
What error code means I need to reset my tankless water heater in Prescott?
The most common error codes after a power outage are 11, 12, 13, and 90 on Rinnai and Navien units. Code 11 means ignition failure - the unit tried three times to light and gave up. Code 12 is flame loss. Code 13 is a fan motor fault. Code 90 is a communication error between the board and the remote.
On Rheem and EcoSmart models, you'll see codes like E1, E2, or E5. E1 is ignition failure, E2 is overheat, and E5 is a water flow issue.
Here's what to do: write down the code, then press and hold the reset button for 5-10 seconds. If the code clears and the unit fires, you're good. If the same code returns within 5 minutes, the problem is mechanical or electrical - not a simple reset.
One note for Prescott homeowners: after a winter outage, code 11 often means the gas line has air in it. Run a hot water tap for 2 minutes to purge the line, then reset again. If the code persists, call us for tankless water heater service Prescott AZ - we'll diagnose the igniter and gas pressure.
Common mistakes to avoid when resetting your tankless water heater
We see these mistakes on 1 in 4 repair calls. Avoiding them saves you time and a service fee.
- Resetting without waiting. If you flip the breaker off and on in under 10 seconds, the board never clears. Wait the full 30 seconds.
- Pressing reset repeatedly. Holding the button for 30 seconds or mashing it 10 times can lock the board into a service mode. Press once, hold 5 seconds, then wait 2 minutes.
- Ignoring a persistent error code. If code 11 or 12 returns three times, stop resetting. You're cycling the unit without fixing the root cause - a clogged burner or a bad igniter.
- Forgetting the remote. Some Navien units have a separate remote display. If the main unit resets but the remote stays blank, unplug the remote for 30 seconds too.
- Not checking the breaker. A power outage can trip the dedicated breaker. If the breaker is off, no amount of resetting will work. Reset the breaker first.
If you've avoided all five and still have no hot water, the issue is beyond a reset. That's when you need a pro.
When to call a professional for tankless water heater repair in Prescott
Call a professional if you've reset the unit twice and it still won't fire, if you smell gas, if you see water leaking from the cabinet, or if the error code returns within 5 minutes of every reset. Those are signs of a failed igniter, a cracked heat exchanger, or a control board that took a surge during the outage.
We handle tankless water heater repair prescott in Hassayampa and across the Prescott area. Our technicians carry replacement igniters, flow sensors, and control boards for Rinnai, Navien, Rheem, and Bosch units. Most repairs are done in one visit, and we test the unit for 15 minutes before we leave.
If your unit is 12-15 years old and this is the third outage-related failure, replacement often costs less than another repair. A new tankless water heater installation Prescott AZ runs $1,800-$3,500 in 2026, including labor and a 6-year warranty. We'll give you a straight answer on repair vs. replace.
Frequently Asked Questions
How do I reset my tankless water heater after a power outage in Prescott AZ?
Turn off the breaker, wait 30 seconds, restore power, then press and hold the reset button for 5 seconds. If your unit lacks a reset button, cycle the breaker off for 2 minutes. Most units fire within 30 seconds after a proper reset.
Why is my tankless water heater not turning on after a power outage in Prescott?
The control board is likely in lockout mode or the igniter failed during the surge. Check the breaker first - outages trip it 40% of the time. If the breaker is on and the display is blank, the board may need replacement. Call us for a diagnostic.
What error code means I need to reset my tankless water heater in Prescott?
Codes 11, 12, 13, and 90 on Rinnai/Navien, or E1, E2, E5 on Rheem, all indicate a reset is needed. Code 11 (ignition failure) is the most common after an outage. Press reset once; if the code returns, it's a mechanical issue.
Should I call a pro to reset my tankless water heater in Prescott AZ?
Yes, if two reset attempts fail, if you smell gas, or if water is leaking. A pro can diagnose the igniter, gas valve, or control board in under an hour. We charge a flat diagnostic fee and waive it if you approve the repair.
How long does a tankless water heater last after a power outage?
A single outage rarely shortens the unit's life. But repeated surges can degrade the control board over 3-5 years. If your unit is over 10 years old and fails after every outage, replacement is the better investment.
Get help with tankless water heater repair prescott in Prescott
If you've reset your tankless water heater and still have no hot water, we can help. Our team serves Prescott, Downtown Prescott, Hassayampa, Yavapai Hill, Williamson Valley, and Prescott Lakes with same-day service.
Call us at +13214978646 for tankless water heater repair prescott. We'll diagnose the issue, give you an upfront price, and get your hot water back on.
