Generic Water Heaters Gas Water Heater Not Producing Hot Water: How to Fix It Yourself
The most common reason a gas water heater stops making hot water is that the pilot light has gone out. Relighting it is usually quick and easy. If the pilot will not stay lit, the thermocouple is probably worn out — this is a cheap and common repair.
⚠️ Safety First
- If you smell a strong gas odor (rotten egg smell), do NOT try to light anything. Leave your home immediately and call the gas company from outside.
- A small whiff of gas near the pilot area when relighting is normal. A strong smell throughout the room is NOT normal.
- Make sure the area is well-ventilated when working on a gas water heater.
- Never use a regular lighter to relight a pilot — use a long-reach lighter to keep your hand away from the burner.
Parts You May Need
Step-by-Step Repair
- 1
Check the pilot light
Look at the gas control valve on the front of the water heater (near the bottom). The knob should be set to the Pilot position. Look through the viewing window or access panel at the bottom of the tank. If you do not see a small blue flame, the pilot is out.
- 2
Relight the pilot light
Turn the gas control knob to Off and wait 5 full minutes for any gas to clear. Then turn the knob to Pilot. Press and hold the knob down (or the separate pilot button). While holding it, use a long-reach lighter to light the pilot through the access opening. Keep holding the knob for 60 seconds after the pilot lights. Then release it. If the pilot stays lit, turn the knob to On and set the temperature to your desired setting.
- 3
If the pilot won't stay lit, check the thermocouple
The thermocouple is a copper tube or wire that sits in the pilot flame. It senses the flame and tells the gas valve to stay open. If the pilot goes out as soon as you release the knob, the thermocouple is likely worn out. You can try gently cleaning the tip with fine sandpaper, but usually it needs to be replaced. Thermocouples are universal and inexpensive.
- 4
Replace the thermocouple
Turn the gas to Off. Disconnect the thermocouple from the gas control valve (it screws off by hand or with a small wrench). Remove the old thermocouple from its bracket near the pilot assembly. Install the new one by reversing the steps — make sure the tip sits directly in the pilot flame. Reconnect it to the gas valve finger-tight plus a quarter turn with a wrench.
- 5
Relight and test
Relight the pilot following the steps above. The pilot should now stay lit after you release the knob. Turn the gas control to On, set the temperature to 120°F, and listen for the main burner to fire up. You should have hot water within 30–45 minutes.
If That Didn't Work
- Gas supply is off (check the gas shut-off valve on the line to the heater)
- Dirty or clogged pilot tube
- Faulty gas control valve (gas valve does not open)
- Sediment buildup in the tank reducing heating efficiency
When to Call a Professional
If you smell a strong gas odor at any point, leave the house and call the gas company. If the pilot lights but the main burner does not fire, the gas control valve may be bad — this is a job for a licensed plumber. If the unit is over 10–12 years old and having recurring issues, replacement is often more cost-effective than repair.
Related Repairs
Generic — Electric Water Heater Not Producing Hot Water
Medium · 30-60 minutes · $0–$30
Generic — Water Heater Leaking From Bottom
Medium · 30-60 minutes · $0–$15
Generic — Water Heater Pilot Light Won't Stay Lit
Medium · 20-45 minutes · $0–$15
Generic — Water Heater Making Popping or Rumbling Noise
Easy · 30-60 minutes · $0–$10
Disclaimer: This guide is for informational and educational purposes only and does not constitute professional repair advice. All repairs are performed at your own risk. RepairItFree.com is not liable for any personal injury, property damage, device damage, voided warranties, or other losses resulting from the use of this information.
If you are unsure about any step — especially anything involving electricity, gas, water, or refrigerant — stop and consult a qualified professional. Your safety is more important than saving money.
See our full Terms of Service for complete legal details.