Residential plumbing · Denver Metro, Colorado

No hot water? Causes and repair

No hot water usually means the pilot or burner isn't lighting on a gas heater, or a heating element or thermostat has failed on an electric one. Some causes you can check safely yourself; most fixes are repairs, not replacements.

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Owned by John Kuykendall, Colorado Master Plumber License #03002471

Two gas tank water heaters installed side by side in a utility room, each with a blue thermal expansion tank, copper water piping and metal vent pipes rising to the ceiling.

Losing hot water is usually a single failed part. Before you call, a few safe checks can narrow it down, and sometimes solve it. If anything below involves opening panels you're not comfortable with, stop and call; water heaters combine gas or high-voltage electricity with hot water under pressure.

Gas water heaters

A gas tank heater needs three things to make hot water: a gas supply, a flame, and a safety system that proves the flame is there. When any of them fails, the burner shuts down.

Pilot is out. On standing-pilot heaters, the thermocouple senses the pilot flame. A worn thermocouple lets the pilot go out and won't let it stay lit.
Electronic ignition won't light. Newer models use an igniter and flame sensor. A dirty flame sensor or failed igniter shows up as a blinking status light.
Gas control valve. The thermostat and valve assembly on the front of the tank can fail; it's a bigger repair.
Venting problem. Some heaters shut down when the flue doesn't draft properly or the combustion air is blocked. That's a safety shutdown, not a nuisance.

Many gas heaters have relighting instructions printed on the label. If you smell gas, don't relight anything; leave and call your gas utility or 911 from outside.

Electric water heaters

Electric tanks usually have two heating elements, upper and lower, each with its own thermostat. That's why you can lose part of your hot water rather than all of it.

Tripped breaker. Check the panel. If it trips again right away, leave it off and call; an element may be shorted.
High-limit reset. A safety switch behind the upper panel trips when water overheats. Resetting it without finding the cause isn't a fix.
Failed element or thermostat. The most common electric repair. Elements fail faster where sediment builds up around them.

When no hot water means replacement

If the heater is out of hot water and there's water around the base, the tank itself may have failed; see leaking water heater. An older heater that needs a gas control valve or several parts at once is also worth weighing against replacement. More on that in water heater repair and replacement.

Running out faster than before

If you still get hot water but it runs out sooner, the usual suspects are sediment taking up room in the tank, a broken dip tube that lets cold water mix at the top, a failed lower element on an electric heater, or winter's colder supply water. A heater that has never kept up may simply be too small for the household.

Signs it's a water heater problem

No hot water anywhere in the house
Only lukewarm water, or it runs out quickly
Pilot won't stay lit
Status light blinking an error code
Breaker for the water heater keeps tripping
Hot water smells like sulfur or looks rusty

How a visit goes

Tell us what you seeGas or electric, any blinking light or error code, whether the pilot is lit, and how old the heater is.
Diagnose the causeWe test the ignition or electrical side, check venting and gas supply, and confirm the tank isn't leaking.
Repair or replaceIf it's a part, we repair it. If the tank is failing or the repair doesn't make sense, we explain why.
Test and confirmWe run the heater through a full cycle and check for proper draft on gas units.

Colorado notes

What's different here

Altitude. Gas burns with less oxygen along the Front Range, so burners and venting have to be set up for elevation per the manufacturer.
Winter demand. Colder incoming water in winter means the heater works harder and recovers more slowly, which exposes weak parts.
Low-NOx rule. Under HB23-1161, new gas water heaters sold in Colorado since January 1, 2026 must meet low-NOx limits, which matters when repair turns into replacement.

What affects the cost

Every home is set up differently, so we price the job after we've seen it. These are the things that move the number.

Which part failedA thermocouple or element is a small part; a gas control valve costs more.
Gas or electricDifferent parts, different diagnosis.
AccessClosets, attics and tight utility rooms take longer.
Age and conditionOn an older tank, a big repair may not be worth it.
VentingDraft problems sometimes trace back to the vent, not the heater.
Parts availabilityCommon parts are stocked; some have to be ordered.

Questions we hear

Why did my water heater stop making hot water overnight?

Usually a single part: the thermocouple or igniter on gas heaters, an element or thermostat on electric ones. A tripped breaker or a gas supply interruption can do it too.

Can I relight my pilot myself?

Many heaters have relighting steps on the label, and following them is fine if you're comfortable. If it won't stay lit, the thermocouple or gas valve likely needs attention. If you smell gas, don't try; leave and call your gas utility.

Why is my hot water only lukewarm?

On electric heaters, one of the two elements has often failed. On gas heaters, sediment, a broken dip tube or a thermostat issue are common causes.

Is no hot water an emergency?

Usually not, unless the tank is leaking. It's worth scheduling soon, though, especially in winter.

How long does a no-hot-water repair take?

Most part replacements are done in one visit if the part is in stock. Some gas valves and model-specific parts have to be ordered.

Should I replace a 12-year-old heater that stopped working?

It depends on what failed. A thermocouple on a sound tank is a sensible repair. A gas valve on an old tank often isn't. We'll give you both options.