No Hot Water? What to Check Before You Call
Most likely causes
- Pilot light out or ignition failure (gas)A draft, a dirty pilot orifice, or a worn thermocouple all put the flame out. The thermocouple is the safety sensor that closes the gas valve when it cannot feel heat, and it is the single most common failure we see. Replacing one runs $150 to $250.
- Tripped breaker or burned out element (electric)Electric tanks heat with an upper and a lower element. A burned element often trips the breaker on its way out, so the heater goes stone cold with no warning. An element swap runs $200 to $400.
- Failed gas control valve or thermostatThe control valve meters gas to the burner, and it sticks or dies on tanks past 8 years old. The tell is a pilot that stays lit while the main burner never fires. Expect $350 to $600 to replace it.
- Sediment burying the burnerNorth Bay water is moderately hard, and the minerals settle as scale on the tank bottom. Enough scale insulates the water from the flame, so the heater runs longer and delivers less. Popping and rumbling sounds are water boiling under that sediment layer.
- Gas supply interruptedA tripped seismic shutoff valve, a valve closed during other work, or PG&E line maintenance all starve the burner. The heater looks fine but nothing lights. Check whether the stove or furnace has gas before blaming the heater.
- The tank is simply doneStandard tank heaters last 8 to 12 years. Past that point, parts start failing in clusters and the tank itself is next in line. If your unit is in that window, stop paying for parts.
Safe checks before you call
- Look through the pilot window (gas)Find the small sight glass near the bottom of the tank. No flame means the pilot is out. Relight it only by following the printed instructions on the tank label, and if you smell gas at any point, stop, leave the house, and call PG&E.
- Check the breaker panel (electric)Find the double breaker marked water heater, usually 30 amps. If it sits between on and off, flip it fully off, then back on, one time only. A breaker that trips again is reporting an electrical fault, so leave it off and call.
- Check the temperature dial (gas)The dial on the gas control box gets bumped to low or to vacation mode more often than people expect, especially on garage units. Make sure it points to its normal setting, about 120 degrees on most models.
- Test more than one faucetRun hot water at the kitchen and two bathrooms. If only one fixture runs cold, the problem is that fixture's cartridge or mixing valve, not the water heater.
- Give the tank time to recoverA 40 gallon gas tank reheats from cold in roughly 30 to 45 minutes, and electric takes 60 to 90. If the household just ran laundry, a dishwasher, and back to back showers, wait an hour before judging the heater.
Call us right away if
- You smell gas near the heater, so leave the house first, call PG&E, then call us.
- The pilot will not stay lit after two attempts, the classic sign of a failed thermocouple.
- The breaker trips again right after a reset, which points to a shorted element or wiring fault.
- The tank is cold and leaking at the same time, because a leaking tank cannot be repaired.
- Hot water comes out rusty or smells like rotten eggs along with the temperature loss.
- The heater is past 10 years old, where repair money is better put toward replacement.
Gas or Electric Changes the Whole Diagnosis
Look at the top of the tank before you do anything else. A gas heater has a flue pipe rising off the top and a gas line feeding a control box near the bottom. An electric heater has a cable or conduit coming in and no flue. Gas units fail at the pilot, the thermocouple, and the control valve. Electric units fail at the elements and thermostats. Both fail at the tank itself once age and scale catch up with the steel.
What the Fix Costs
- Thermocouple or pilot assembly: $150 to $250
- Electric heating element: $200 to $400
- Gas control valve: $350 to $600
- New tank heater, installed: $1,800 to $3,600
Install prices include the permit and the items California code requires on every swap, meaning seismic strapping and an expansion tank where the system calls for one. Our water heater replacement cost guide has the line by line breakdown, including tankless conversions at $4,500 to $9,000.
A Local Note on Gas Service
PG&E supplies the gas for nearly every tank heater in Sonoma and Marin County. When crews interrupt service for line work, or a meter gets shut after a leak report, standing pilots go out and stay out. If your cold shower lines up with utility trucks on the street, check the pilot before you decide the heater died. PG&E relights pilots after planned outages, and we handle relights and safety checks if you would rather not wait for a utility window.
Repair or Replace
Check the manufacture date on the serial number sticker. Under 8 years old with one failed part, repair it and move on. Past 10 years, put the repair money toward a new unit, because the next thing to go is usually the tank, and no part fixes a rusted tank. Between 8 and 10 is a judgment call based on the repair quote and how hard your water has been on the unit.
What We Do on a No Hot Water Call
We test the thermocouple or the elements, verify gas pressure or voltage, pull and inspect the burner, and quote a firm price before touching anything. The truck carries the common parts, so most of these calls end with hot water restored in one visit. If the tank is done, we can usually set a new one the same day.
Frequently asked questions
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