By Brent Applegate, Licensed Master Plumber | Polly Plumbing | License No. RMP-42199 Serving Keller, Southlake, Trophy Club, Roanoke, Flower Mound, Colleyville, North Richland Hills, and all of Tarrant and Denton Counties. Based in Keller, TX.
Polly Plumbing provides same-day water heater installation in Southlake TX for confirmed failures and across all of Tarrant and Denton Counties.
No Hot Water in Keller TX? Start Here
If your gas water heater has no hot water, check the pilot light first it is out roughly half the time and can be relit from the label on your unit in under five minutes with no tools. If your electric water heater has no hot water, check the circuit breaker first. Those two checks resolve the majority of no hot water calls in Keller and Tarrant County before a plumber is needed. The full diagnostic sequence for both fuel types follows below.
A Real Example From a Flower Mound Homeowner
A homeowner in Flower Mound called at 7am. Her 8-year-old gas water heater had stopped producing hot water overnight. No warning. Just cold water from every hot tap.
Brent walked her through a quick phone assessment. The pilot light was out. He talked her through the relight sequence on the unit label. The pilot lit and stayed lit. Full hot water was restored within the hour as the tank reheated.
No service call needed. No parts. The pilot had gone out not uncommon after a brief gas pressure fluctuation overnight from ATMOS Energy when demand spiked during a cold spell. She called back a week later to book an annual maintenance visit and ask about the thermocouple, because Brent had mentioned on the phone that if the pilot went out again, or would not stay lit after relighting, the thermocouple was likely the cause and a service call would be warranted.
That context, knowing the difference between a one-time pilot outage and a developing thermocouple failure is exactly what this article gives you before you call anyone.
No Hot Water in Keller TX: Which Problem Do You Actually Have?
These are two different problems that both sound like “no hot water” but have completely different causes.
Problem A — Completely cold water from every hot tap: The unit has stopped heating entirely. You open a hot tap and get cold water with no warmth at all. This is what most people mean when they say “no hot water in Keller TX.”
Problem B — Hot water that runs out faster than it used to: The first few minutes of hot water are normal but the tank runs cold after a shorter period than before. You used to get 30 minutes of hot showers. Now you get 10 to 15.
Problem B is almost always sediment accumulation in Keller and Tarrant County. Hard water deposits a layer of calcium and magnesium on the tank floor with every heating cycle. Over years without flushing, that sediment layer insulates the burner from the water, dramatically reducing heating efficiency and effective tank capacity. A 50-gallon tank with four inches of sediment on the floor is effectively a much smaller tank. This is addressed with a professional tank flush service, covered later in this article.
If you have Problem A — completely cold water — find your fuel type below and work through the relevant sequence.
Gas Water Heater No Hot Water in Keller TX: The Diagnostic Sequence
Gas water heaters stop producing hot water for five reasons, in order of how commonly Brent sees them in Keller and Tarrant County.
Cause 1: Pilot Light Out — Check This First
The pilot light is a small continuous flame that ignites the main burner when the thermostat calls for heat. If the pilot goes out, the main burner cannot ignite and the tank stops heating. This is the most common cause of sudden no hot water in Keller TX on a gas unit that was working fine the day before.
How to check: Look through the small observation window at the bottom of the unit. If the pilot is lit, you will see a small blue flame. If you see nothing, the pilot is out.
How to relight: The relight procedure is on the label affixed to your unit. The general sequence is: set the thermostat to the lowest setting, turn the gas control dial to pilot, press and hold the pilot button or gas control knob while pressing the igniter button until the pilot lights, continue holding for 30 to 60 seconds after the pilot ignites to allow the thermocouple to heat up, then slowly release the control. If the pilot stays lit, set the thermostat back to your desired temperature.
If the pilot lights but immediately goes out when you release the button: This is the thermocouple. Move to Cause 2.
If the pilot will not light at all: Check that the gas supply valve to the unit is fully open. Check that other gas appliances in the home are working. If gas supply is confirmed but the pilot still will not light, the gas valve may have failed — Cause 4.
Cause 2: Failed or Failing Thermocouple
The thermocouple is a safety sensor positioned in the pilot flame. It generates a small electrical current when heated by the pilot flame, which signals the gas valve to remain open and allow gas to flow to the pilot. When the thermocouple deteriorates, it generates a weak or inconsistent signal. The gas valve interprets this as “pilot is not lit” and shuts off the pilot gas as a safety measure. The pilot appears to go out spontaneously or cannot stay lit longer than a few seconds after you release the control.
This is the most common cause of a pilot light that will not stay lit in Keller and Tarrant County gas water heaters, and the most common single paid water heater repair Brent performs on tank units in this market. Thermocouple deterioration is a wear item, typically lasting 5 to 10 years depending on the unit and operating conditions.
Signs: The pilot lights when you hold the button but goes out within seconds to minutes of releasing it. This happens repeatedly regardless of how long you hold the button before releasing.
What to do: A licensed plumber replaces the thermocouple, which restores normal pilot operation. Cost: $350 to $450 including labor. This repair is worth doing on units under 12 years old in Tarrant County hard water without a softener, under 14 years with a softener.
Cause 3: Sediment Insulating the Burner
In Tarrant County hard water, calcium and magnesium deposits accumulate on the tank floor with every heating cycle. On units that have gone four or more years without a professional flush, this sediment layer can be several inches thick. The sediment insulates the burner from the water above it, forcing the burner to run longer and hotter to heat the tank.
The symptoms are not always complete cold water — more commonly a tank that recovers very slowly, produces rumbling or popping sounds during the heating cycle as water boils through the sediment layer, and runs out of hot water faster than it used to. But in severe cases the sediment insulation can become significant enough that the unit essentially stops maintaining temperature.
What to do: A professional tank flush service removes the accumulated sediment and restores normal burner efficiency. This is a maintenance service, not a repair. Cost: $100 to $300. In Tarrant County hard water, annual flushing is the correct maintenance interval. Units that have never been flushed and are more than five years old in this area almost certainly have significant sediment accumulation.
Cause 4: Failed Gas Valve
The gas control valve on a water heater is a combined component that houses the thermostat, the gas flow controls for both the pilot and the main burner, and the safety shutoff. Gas valve failure can produce a range of symptoms from a pilot that will not light to a unit that ignites but does not maintain temperature. Gas valve failures are less common than thermocouple failures but do occur, particularly on units more than 10 years old.
Signs: Pilot will not light at all despite confirmed gas supply and correct procedure, or unit fires but does not maintain the target temperature across multiple heating cycles. Many modern gas water heaters have a status light that blinks a code when a fault is detected — check yours if present.
What to do: Call a plumber. Gas valve replacement: $600 to $800 including parts and labor. On units more than 10 years old in Tarrant County hard water, get a replacement cost quote at the same time — a gas valve replacement on an aging unit may not be the best economic choice.
Cause 5: Thermostat Failure
The thermostat on a gas water heater detects when the water temperature drops below the setpoint and opens the gas valve to fire the main burner. A failed thermostat may not detect the temperature correctly, either failing to call for heat (producing cold water) or failing to shut off (producing dangerously hot water).
Signs: Unit appears to fire based on pilot status but never heats the water adequately. Or water is consistently too hot regardless of thermostat setting.
What to do: Call a plumber. Thermostat replacement on a gas unit: $400 to $500 including parts and labor. On units over 10 to 12 years old, weigh against replacement cost.
Electric Water Heater No Hot Water in Keller TX: The Diagnostic Sequence
Electric water heaters stop producing hot water for four reasons, in order of how commonly Brent sees them in this area.
Cause 1: Tripped Circuit Breaker — Check This First
An electric water heater requires a dedicated 240-volt circuit. If the circuit breaker has tripped, the unit receives no power and produces completely cold water with no other symptoms.
How to check: Go to your electrical panel. Find the breaker labeled for the water heater — typically a double-pole breaker (two switches joined together). If it has tripped, it will be in the middle position rather than fully on or fully off. Reset it by pushing fully to off, then back to on.
If the breaker trips again immediately: Do not reset it again. A breaker that resets and immediately trips indicates an electrical fault — a failed heating element drawing excessive current or a wiring fault. Call a plumber or electrician.
If the breaker holds and the unit produces no hot water after 1 to 2 hours: Continue to Cause 2.
Cause 2: Tripped High-Limit Safety Switch
Electric water heaters have a high-limit safety switch that cuts power to the heating elements if the water temperature exceeds a safe threshold. When triggered, it requires a manual reset before the unit will heat again.
In Keller and Tarrant County, the high-limit trips more frequently than average in hard water areas because sediment on the tank floor causes the lower thermostat to run the heating element longer trying to reach target temperature, occasionally overheating the surrounding water. A high-limit trip that recurs after resetting is telling you the sediment problem needs to be addressed, not just the switch.
How to reset: Turn off the circuit breaker for the water heater. Remove the upper access panel by unscrewing the panel screws. You will see the thermostat behind insulation. The red high-limit reset button is typically visible above the thermostat. Press it firmly until you feel or hear a click. Replace the panel and insulation, restore power, and wait 1 to 2 hours for the tank to reheat.
If the high-limit trips again within a few days: Call a plumber. The sediment level needs assessment and likely a tank flush service.
Cause 3: Failed Heating Element
Tank electric water heaters have two heating elements — one in the upper portion of the tank and one in the lower portion. The upper element heats the top section of the tank and triggers the thermostat for the lower element. When the upper element fails, the lower element never receives its trigger and the entire tank goes cold. When the lower element fails, the upper element heats only the top portion of the tank, producing a small amount of hot water that quickly runs cold.
Heating element failure in Tarrant County hard water is accelerated by mineral deposits forming on the element surface. The deposits insulate the element, cause it to run hotter, and shorten its operating life. Annual tank flushing reduces this risk significantly.
Signs: Completely cold water suggests upper element failure. A small amount of hot water that quickly runs out suggests lower element failure.
What to do: Call a plumber for water heater repair. Element testing and replacement: $550 to $750 including parts and labor for a single element. Worth repairing on units under 10 to 12 years old.
Cause 4: Failed Thermostat
Electric water heaters have two thermostats — one for each heating element. A failed thermostat may not correctly call for heat, producing cold or insufficiently warm water, or may not correctly shut off, producing dangerously hot water or tripping the high-limit switch repeatedly.
Signs: The circuit breaker is fine, the high-limit is not tripped, but the unit is not heating adequately. Or the high-limit keeps tripping despite normal usage.
What to do: Call a plumber. Thermostat testing and replacement: $400 to $500 per thermostat. On units under 10 years old, worth replacing. On units 12 or more years old in Tarrant County hard water, get a replacement cost comparison.
What About Slow Recovery Time?
Recovery time — how long the tank takes to reheat after a hot water draw — varies by season in Keller and Tarrant County in a way many homeowners do not anticipate.
In midsummer, incoming cold water to the tank may be 72 to 74°F. In January following a cold snap, it may drop to 50 to 54°F. A gas water heater that recovers in 40 minutes in July may take 55 to 65 minutes in January. This is not a no hot water failure — it is physics. If complaints about slow recovery only happen in winter and summer performance is normal, the seasonal groundwater temperature is the most likely explanation before any component failure is diagnosed.
Significant sediment accumulation speeds up apparent recovery time complaints — the unit takes longer and longer to recover even in mild weather, and the problem is worse in winter when the thermal demand is already higher.
The Sediment Problem: How Tarrant County Hard Water Causes No Hot Water Issues Over Time
This is the cause most homeowners in Keller and Tarrant County have not heard clearly explained.
Every gallon of very hard Tarrant County water (15 to 25 grains per gallon) that enters your tank deposits a fraction of a grain of calcium and magnesium on the tank floor when it heats. Over months and years, these deposits accumulate into a sediment layer. On units that have never been flushed, this layer can reach several inches deep after five to seven years in this area’s water.
The sediment layer has two effects. First, it reduces the effective volume of hot water in the tank — a 50-gallon tank with four inches of sediment holds meaningfully less usable hot water. Second, it insulates the burner (gas) or heating element (electric) from the water above, forcing the heating system to work harder and run longer to achieve the same output temperature.
The result: no hot water complaints increase, recovery time grows, and the unit runs its burner or elements more frequently and for longer, which accelerates wear on those components. The U.S. Department of Energy recommends annual tank flushing specifically because sediment buildup is one of the leading causes of efficiency loss and premature failure in residential water heaters — a finding that directly reflects what Brent sees in the Keller and Tarrant County market.
A professional tank flush service connects a hose to the drain valve, opens the cold water supply at full flow, and flushes the accumulated sediment out through the drain. On heavily silted units, this can take multiple flush cycles before the water runs clear. This service should be done annually in Tarrant County hard water.
When to Repair and When to Replace
A no hot water service call in Keller and Tarrant County often presents a choice: repair the failed component or replace the unit. Here is the honest framework.
Repair is the right choice when: The unit is under 10 years old in Tarrant County hard water without a softener, or under 12 years old with a softener. The failed component is a wear item — thermocouple, heating element, thermostat — rather than the gas valve, tank body, or heat exchanger. No other signs of tank deterioration — water is clear, no significant sediment buildup, no rust. Repair cost is under 40 percent of replacement cost.
Replace is the right choice when: The unit is 12 or more years old without a softener, or 14 or more years old with a softener. The gas valve has failed on an aging unit — this component cost approaches the replacement decision threshold. Multiple component failures in the past 12 to 24 months. Significant sediment accumulation that a flush cannot fully remediate on an older unit. The homeowner is considering a tankless upgrade at this decision point.
For a full breakdown of what to expect from a replacement, including all-in costs and brand recommendations for Tarrant County hard water, see our water heater replacement cost guide for Keller TX.
What Polly Does on Every No Hot Water Call in Keller TX
When you call Polly Plumbing for no hot water in Keller, Southlake, Trophy Club, Roanoke, Flower Mound, Colleyville, or anywhere in Tarrant County and Denton County, Brent walks you through the self-check on the phone first. If the pilot relight sequence restores operation, you do not need a service call.
If a visit is needed, you get a text with Brent’s photo before he arrives. The visit starts with the complete diagnostic sequence, component testing where needed, and an honest assessment of repair versus replacement with both cost estimates in writing.
If the diagnosis is a thermocouple or heating element — the two most common findings in this market — Brent arrives with replacement components for the major brands (Rheem, Bradford White, A.O. Smith, State) on the truck and completes the repair on the same visit in most cases.
One of our North Richland Hills customers told us after a thermocouple replacement that Brent had explained more about how her water heater worked in 20 minutes than she had learned in the 11 years she had owned the house. Understanding what had failed and why it had failed at this point in the unit’s service life made the repair decision completely clear.
There is no emergency surcharge at Polly Plumbing. We arrive same-day on confirmed failures and charge the same price as a scheduled repair. Call us at (817) 286-3446.
Repair Cost Reference for Keller and Tarrant County 2026
| Diagnosis | Repair | Typical Cost | Notes |
|---|---|---|---|
| Pilot out — relight works | None | $0 | Brent walks you through the relight sequence on the phone — no service call needed if it holds |
| Thermocouple replacement (gas) | Parts and labor | $350 to $450 | Most common paid repair on gas units in this market |
| Tank flush (sediment) | Service | $100 to $300 | Annual in Tarrant County hard water |
| Heating element replacement (electric) | Parts and labor | $550 to $750 | Single element; worth it under 12 years |
| Thermostat replacement | Parts and labor | $400 to $500 | Gas or electric |
| Gas valve replacement | Parts and labor | $600 to $800 | Compare to replacement on units over 10 years |
| High-limit reset and sediment assessment | Service call | $85 to $150 | Includes sediment evaluation |
| Full unit replacement (50-gal gas) | Installed | $2,900 to $3,300 | Same-day in Keller area |
Frequently Asked Questions About No Hot Water in Keller, TX
Why do I have cold water when my water heater appears to be running?
For a gas unit, the most common cause of no hot water in Keller TX is a pilot light that has gone out or a thermocouple failing to hold the pilot lit. For an electric unit, the most common cause is a tripped circuit breaker or a failed upper heating element. Both produce completely cold water from an apparently normal unit. The gas relight sequence and the circuit breaker check are the first self-checks before calling a plumber.
My water heater pilot light will not stay lit. What is wrong?
The most common cause in Keller and Tarrant County is a failing thermocouple — the safety sensor positioned in the pilot flame that signals the gas valve to remain open. When the thermocouple deteriorates, the pilot lights when you hold the button but goes out within seconds to minutes of releasing it. Thermocouple replacement: $350 to $450. This is the most common single paid repair Brent performs on gas water heaters in this area.
Why does my hot water run out faster than it used to?
In Keller and Tarrant County this is almost always sediment accumulation on the tank floor. Tarrant County hard water (15 to 25 GPG) deposits calcium and magnesium on the tank floor with every heating cycle. Over years without flushing, this sediment layer reduces effective tank capacity and insulates the burner or heating element from the water above it. Annual flushing prevents this. A professional flush service restores capacity on units where sediment has not yet caused permanent damage.
What is the high-limit switch on my electric water heater?
A safety device that cuts power to the heating elements if the water temperature exceeds a safe threshold. It requires a manual reset after tripping. In Tarrant County hard water, it trips more frequently than average because sediment on the tank floor causes the heating element to run longer, occasionally overheating the surrounding water. A high-limit that trips repeatedly after resetting is a signal that sediment accumulation needs to be addressed, not just the switch.
How long does a tank water heater take to reheat after running out?
A 50-gallon gas water heater in Keller and Tarrant County typically recovers in 40 to 50 minutes in summer conditions. In January following a cold snap when incoming groundwater drops to 50 to 54°F, the same unit may take 60 to 70 minutes. If recovery time has been increasing gradually regardless of season, sediment accumulation is the most likely cause rather than a seasonal groundwater issue.
Should I repair or replace a water heater with no hot water in Keller TX?
It depends on the nature of the failure and the unit’s age. Thermocouple and heating element failures are worth repairing on units under 10 to 12 years old in Tarrant County hard water. Gas valve failures on units over 10 years old approach the replacement decision threshold — get both quotes and compare. Any unit showing tank corrosion (rust in the water, visible rust on the tank exterior) should be assessed for replacement regardless of which component has failed.
How does Tarrant County hard water cause no hot water problems?
Tarrant County water runs 15 to 25 grains per gallon of hardness — roughly double the national average. That hardness deposits calcium and magnesium on heating elements and tank floors faster than most other areas in the country, causing the thermocouple, heating elements, and gas valves to fail earlier than their rated service life. It also creates the sediment layer that reduces effective tank capacity and forces the burner to work harder on every heating cycle. Annual flushing and timely component replacement are the two most effective countermeasures.
Written by Brent Applegate, Licensed Master Plumber, Polly Plumbing. Texas License RMP-42199. Based in Keller, TX. Serving Tarrant and Denton Counties.
Published: May 2026. Last reviewed: May 2026.