No Hot Water in the House? How to Troubleshoot Gas, Electric and Tankless Water Heaters in Fort Collins

No hot water? Quick diagnosis by symptom

Lukewarm water or hot water that runs out fast

Some hot water but not enough usually means the heater is falling behind or cold water is mixing into the hot. Most of these causes come from Bradford White’s electric service manual but apply to gas tanks too:

• Thermostat set low. The Department of Energy suggests 120°F for most homes, and Rheem and Bradford White both list a low setting as a cause of not enough hot water.
• A shower valve or mixing valve. If one shower runs lukewarm while the kitchen tap is hot, suspect that shower’s valve. Code limits shower and tub valves to 120°F, and a limit stop set too low or a worn cartridge can keep one fixture cool. Rinnai also flags faulty fixture valves and mixing valves that let cold water bleed into the hot lines.
• Broken dip tube. The dip tube carries incoming cold water to the bottom of the tank. Bradford White lists a damaged dip tube as a cause; when it breaks, cold water mixes in near the top, where hot water leaves.
• Sediment. Sediment on electric elements slows recovery, and Rheem traces a rumbling gas tank to scale and sediment.
• An undersized heater or a busy hour. Rheem notes that usage can simply exceed the heater’s capacity, so wait for it to recover. If it happens every day, the heater may be too small for the household.
• Colder incoming water in winter. Bradford White lists very cold inlet water as a cause. Water from the street is typically colder in winter, so a tank takes longer to recover and a tankless unit has to raise the temperature further, which can cut its flow at the set temperature; Department of Energy guidance puts a typical gas tankless unit at about a 70°F rise at 5 gallons per minute.

Safe checks, in order

1. Gas smell or CO alarm: leave the house and call the gas utility or 911 from outside.
2. Water on the floor: close the shutoff valve on the cold water supply pipe at the heater, turn off the gas or the breaker, and see emergency water heater repair. Leaking tanks are scheduled first.
3. Test more than one hot tap to tell a whole-house problem from one fixture.
4. Check the fuel: gas valve open, other gas appliances working, propane in the tank.
5. Check the power: the breaker for an electric tank; the outlet, GFCI and breaker for power vent and tankless units.
6. Check the setting on the gas control or tankless controller.
7. Read the display or status light and note any code or flash pattern.
8. Relight or reset once, following the label or manual. If it fails again, stop.

When to call a plumber

Call when a relight or reset doesn’t hold, when the fix involves gas, venting or wiring, or whenever water is leaking, including:

• A pilot that won’t light or won’t stay lit after one try.
• A tripped FVIR or combustion shutoff.
• A breaker or high-limit that trips again.
• A tankless code that returns after a reset.
• Soot, scorch marks or a yellow flame, which Rheem links to restricted air openings or too little combustion air.
• Any leak from the tank itself.

Our water heater repair in Fort Collins team works on gas, electric and tankless heaters. Every job is done by licensed plumbers covered by liability insurance, with a written, itemized quote before work starts and honest repair-or-replace advice. For a sense of scale, Angi’s December 2025 repair guide puts a thermocouple at about $150 or less, an electric heating element at $200-$300 and a gas control valve at about $350 on average; those are national figures, not our prices.

If the tank is leaking or near the end of its life (the Department of Energy says most storage water heaters last 10 to 15 years), see our page on water heater replacement in Fort Collins; we handle the permit and inspection on every replacement.