Water Heater Not Heating — Troubleshooting Guide

No hot water is a problem you notice immediately. The fix depends on whether you have a gas or electric water heater.

First: Check the Basics

• Age: Water heaters last 8-12 years. If yours is older, replacement may make more sense than repair.
• Size: Is demand exceeding capacity? (Running out during showers suggests undersized or failing heater)
• Vacation mode: Some heaters have a vacation or pilot setting that reduces temperature.

Gas Water Heaters

Check the Pilot Light

Look through the viewing window at the base. You should see a blue flame.

If pilot is out:

1. Turn gas valve to OFF
2. Wait 5 minutes (gas to dissipate)
3. Turn to PILOT
4. Press and hold the pilot button
5. Light the pilot (button or electronic igniter)
6. Hold for 30-60 seconds
7. Release and turn to ON

If pilot won’t stay lit:

• Thermocouple may be faulty ($15-30 part)
• Gas supply issue
• Draft blowing out pilot

Check the Thermostat

Should be set to 120°F. Turn it up slightly and listen for the burner to ignite.

Check the Burner

When calling for heat, you should hear/see the burner ignite. No ignition may mean:

• Dirty burner (clean it)
• Faulty gas valve
• Thermostat failure

Electric Water Heaters

Check the Breaker

Electric water heaters use 240V and have a dedicated breaker. Make sure it hasn’t tripped.

Check the Reset Button

There’s a high-temperature reset button on the upper thermostat. If it’s tripped:

1. Turn off the breaker
2. Remove the access panel
3. Press the red reset button
4. Replace panel and restore power

If it trips again: There’s an underlying problem (faulty thermostat, grounded element).

Check the Heating Elements

Electric heaters have one or two elements. They can burn out.

Testing (power OFF):

1. Turn off breaker
2. Access the elements (behind panels)
3. Disconnect wires
4. Test continuity with multimeter
5. No continuity = bad element ($10-30 part)

Check the Thermostats

Upper and lower thermostats control the elements. They can fail.

Testing: Check voltage to elements when calling for heat. If power is reaching elements but they’re not heating, elements are bad. If no power reaches elements, thermostat is bad.

When to Replace vs. Repair

Repair if:

• Heater is under 8 years old
• Problem is a replaceable part (element, thermostat, thermocouple)
• Tank is not leaking

Replace if:

• Heater is 10+ years old
• Tank is leaking
• Multiple components have failed
• Rust in hot water (tank corrosion)

When to Call a Pro

• You smell gas (call immediately, leave house)
• You’re not comfortable with gas appliances
• Electrical testing beyond your skill level
• Tank is leaking
• Multiple repairs haven’t helped

Cost: $150-300 for most repairs, $1,000-2,500+ for replacement including installation.

The Bottom Line

Gas heaters: check the pilot light first. Electric heaters: check the breaker and reset button first. Many repairs are DIY-able, but water heaters involve gas and/or 240V electricity — don’t push beyond your comfort level.