No Hot Water? A Denver Homeowner's Troubleshooting Checklist

Published 2026-03-04 · Denver Water Heater Service Center

Before anything else: if you smell gas, stop. Leave the house, and call 911 and Xcel Energy's gas emergency line from outside. Do not flip switches.

If your water heater is electric

1. Check the breaker. It is a double-pole breaker, often labelled "WH". A tripped breaker sometimes looks almost normal — push it fully off, then back on.
2. Check the reset button. Remove the upper access panel, fold back the insulation, and look for a red button. Press it once. If it trips again, stop and call — there is a live fault.
3. Feel the pattern. No hot water at all points at the upper circuit. Hot water that runs out in ten minutes points at the lower element. Lukewarm all day points at the upper element or a calibration problem.

If your water heater is gas

1. Look for a pilot flame through the sight glass at the base.
2. If it is out, relight it by the printed instructions. Control to OFF, wait five full minutes, then PILOT, press and hold, ignite, and keep holding for 30–60 seconds before releasing.
3. If it will not stay lit after two tries, stop. Usually a thermocouple, sometimes a dirty pilot orifice or a draft problem. See pilot and thermocouple repair.
4. Check that the gas is actually on — the yellow-handled valve on the supply line should run parallel to the pipe. If other gas appliances are also out, the problem is upstream.

Checks that apply to both

• Is the thermostat turned down? It happens more often than you would think, particularly after someone has been working in the basement.
• Is it only one fixture? Then the heater is fine — you have a failed mixing cartridge or a closed angle stop at that fixture.
• Did it start after recent plumbing work? Crossed hot and cold connections at a new fixture let cold water flow backward into the hot line and cool the whole system.
• Is the household bigger than it used to be? Nothing is broken; the tank is undersized. See our sizing guidance.

When to stop and call

Call rather than continue if: the reset trips a second time; the pilot will not hold after two attempts; there is water on the floor; the relief valve is discharging; you see soot or scorching near the burner; or the water is scalding rather than absent. Those last three are safety issues rather than inconveniences.

When you do call, have the brand, the fuel type, the capacity and the approximate age ready — it determines what we load on the truck. 720-735-8936, answered 24 hours.

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Questions about your own water heater? Call 720-735-8936 — we answer 24 hours a day and we are happy to talk through a problem whether or not it turns into a job.