Water Heater Not Heating? Here’s What to Check Before You Call
About 75% of winter water heater “no heat” calls trace to a single failed part: a heating element, thermostat, or pilot light.
The good news is that most fixes cost $150–$300, and many issues can be diagnosed before a technician arrives.
In Utah, winter demand creates a perfect storm:
- Your heater works harder in cold weather
- High elevation affects combustion in gas heaters
- Hard water increases sediment buildup
Understanding these factors can help you diagnose the problem quickly and avoid unnecessary repairs.
Quick Answer
Most no hot water problems come from:
- Failed heating element (electric heaters)
- Faulty thermostat (both gas and electric)
- Pilot light failure (gas heaters)
Less common causes include:
- bad thermocouple
- gas control valve failure
- sediment buildup blocking heating components
Safe checks you can perform
- Drain sediment from the tank
- Verify thermostat setting
- Check whether the pilot light is visible (gas units)
Call a plumber immediately if you notice
- Gas smell
- Water pooling under the heater
- Persistent ignition failure
Typical repair costs range from $150 to $700, depending on the part.
Symptoms and What They Mean
No Hot Water at All
If water stays completely cold:
Electric heaters:
Likely a failed heating element.
Gas heaters:
Possible causes include:
- pilot light out
- faulty thermocouple
- bad gas control valve
If the heater worked yesterday but not today, a component likely failed suddenly.
Water Heats Slowly Then Turns Cold
This often indicates sediment buildup inside the tank.
Sediment acts like insulation around the heating element or burner, preventing efficient heating.
A tank flush typically restores normal performance.
Water Is Warm but Not Hot
Possible causes include:
- thermostat accidentally lowered
- partially failing heating element
Check the thermostat setting first.
Recommended temperature: 120°F
Only One Faucet Has No Hot Water
If other fixtures still have hot water, the problem is likely:
- faucet cartridge issue
- hot water shutoff valve under sink partially closed
This is usually not a water heater problem.
Humming Sound but No Heat
Electric heaters:
- heating element stuck or failing
Gas heaters:
- fan or pump running but burner not igniting
Both conditions require professional service.
Safe Checks You Can Perform
Check the Thermostat
Look for the thermostat dial or digital display on the side of the heater.
Recommended setting:
120°F
If someone lowered it below 100°F, raise it back to 120°F and wait about 30 minutes.
Never exceed 140°F due to scald risk.
Drain Sediment (Heaters Over 5 Years Old)
Sediment buildup reduces heating efficiency.
Steps:
- Turn off the heater
- Place a bucket under the drain valve
- Open the valve slowly
- Drain about 2 gallons of water
Drain until the water runs clear.
Close the valve and turn the heater back on.
Heating should improve within one hour.
Check the Pilot Light (Gas Units)
Open the lower access panel.
You should see a small blue flame.
If the pilot is out, the likely cause is:
- thermocouple failure
- gas control valve failure
Do not attempt repeated relighting. Call a plumber.
Inspect for Water Leaks
Check under the tank and around pipes.
If everything is dry, the heater itself likely hasn’t failed.
Pooling water may indicate tank failure.
Check Circuit Breaker (Electric Units)
Water heaters use a dedicated breaker.
Reset the breaker:
- Switch OFF
- Switch back ON
If it trips again quickly, the heating element is likely failing.
When This Becomes Dangerous
Gas Smell Near the Heater
This is an emergency.
Leave immediately and avoid:
- electrical switches
- appliances
- open flames
Call your gas provider.
Dominion Energy Utah emergency line:
1-888-221-7070
Rotten Egg or Sulfur Smell
This usually indicates hydrogen sulfide bacteria in the tank.
While not immediately dangerous, the system should be flushed within a day.
Water Pooling Around the Tank
A leaking tank often means internal corrosion.
Slow leaks from valves may be repairable.
Leaks from the tank body require replacement.
Turn off the home’s water supply and call a plumber.
Pilot Light Won’t Stay Lit
Repeated pilot failure usually indicates:
- failing thermocouple
Do not keep attempting to relight the pilot.
Call a technician.
Popping or Rumbling Sounds
This often means heavy sediment buildup.
Drain and flush the tank.
If noises continue afterward, the heating element may be damaged.
What a Technician Will Check
When a plumber arrives, they usually follow a standard diagnostic process.
Measure Water Temperature
They compare faucet temperature with the thermostat setting.
If the water is 20°F or more below the setting, the heating system is malfunctioning.
Inspect Pilot Light and Ignition (Gas Units)
They confirm the pilot light is burning properly and test the thermocouple.
Thermocouple replacement typically costs:
$100–$200
Test Heating Element (Electric Units)
A multimeter checks whether the element is conducting electricity.
Failed elements read zero ohms and must be replaced.
Typical cost:
$200–$300 installed
Inspect Sediment Buildup
Technicians may partially drain the tank to inspect sediment accumulation.
Heavy sediment suggests the heater is nearing end of life.
Utah hard water often shortens lifespan to 8–10 years.
Verify Gas Pressure and Combustion
Utah homes sit at roughly 4,200 feet elevation.
At higher altitude, combustion efficiency changes.
Technicians check:
- gas orifice size
- burner pressure
- air mixture
Provide Repair or Replacement Recommendation
Technicians typically apply the 50% rule.
If repair cost exceeds 50% of replacement cost, replacement is recommended.
Typical Water Heater Repair Costs
| Repair Type | Typical Cost |
|---|---|
| Heating element replacement | $200 – $300 |
| Thermostat replacement | $100 – $200 |
| Thermocouple replacement | $100 – $200 |
| Pilot light repair | $50 – $150 |
| Gas control valve replacement | $300 – $500 |
| Tank flush | $150 – $300 |
| Diagnostic service call | $100 – $150 |
| Emergency service surcharge | $50 – $150 |
Utah Winter and Altitude Considerations
Utah’s Wasatch Front averages about 4,200 feet above sea level.
At this elevation:
- oxygen levels are 15% lower than sea level
- gas heaters experience different combustion conditions
Manufacturers test heaters at sea level, where combustion air is plentiful.
At Utah elevation:
- pilot lights blow out more easily
- thermocouples can become less responsive
Winter Effects
Winter increases strain because:
- groundwater entering the heater is colder
- heaters must run longer to reach 120°F
- partially failing elements fail faster
Altitude Derating
Contractors may adjust burner output for elevation.
Typical adjustment:
Reduce burner orifice size by ~4% per 1,000 feet of elevation
If your heater repeatedly fails to ignite, altitude derating may fix the problem.
Typical adjustment cost:
$150–$300
Hard Water Effects
Utah’s hard water accelerates sediment buildup.
Annual flushing greatly reduces winter failures.
Find Local Help
No-heat emergencies require fast diagnosis.
Licensed plumbers can usually identify the problem within 30 minutes and often repair the heater the same day.
Helpful service pages:
- Water Heater Repair: /water-heater-repair/
- Salt Lake City: /ut/salt-lake-city/water-heater-repair/
- Salt Lake County: /ut/salt-lake-county/water-heater-repair/
- Utah Locations: /locations/
Scheduling repairs during normal business hours avoids emergency surcharges.
Frequently Asked Questions
Can I relight the pilot light myself?
It is possible, but risky if you’re unfamiliar with gas appliances.
If the pilot will not stay lit after one attempt, call a plumber.
Repeated attempts can flood the combustion chamber with gas.
Why does my water heater fail in winter?
Winter stresses heaters because:
- incoming water is colder
- elements must run longer
- altitude weakens combustion
Partially failing components often fail during winter demand.
Is heating element failure dangerous?
No.
The element simply stops heating.
You’ll lose hot water but there is no safety hazard.
How much does emergency repair cost in Utah?
Emergency calls add $50–$150 to standard repair costs.
Total repairs typically range from $150–$700.
Should I repair or replace a 10-year-old heater?
Use the 50% rule.
If repair costs exceed half of replacement cost, replacement is usually better.
What’s the difference between no heat and weak heat?
No heat:
Heating element or burner has failed completely.
Weak heat:
The heater works but cannot maintain temperature due to:
- sediment buildup
- thermostat misadjustment
- aging components.
Sources {#sources}
Information current as of March 2026.
Sources include:
- Angi Water Heater Repair Cost Guide
- HomeGuide Water Heater Repair Cost Data
- Carter’s My Plumber Repair Cost Analysis
- Salmon HVAC Utah Winter Water Heater Guide
- Water Heater High Altitude Performance Guide
- Sunset Plumbing Utah County Resources
- Think Tank Home Altitude Solutions
Repair costs, seasonal trends, and altitude adjustments are updated annually to reflect contractor practices and labor rates in Utah.