A water heater pilot light that will not stay lit has a way of ruining a morning faster than a traffic jam. You turn the tap, expect a comfortable shower, then get a cold surprise. At JB Rooter and Plumbing Inc, we see this problem weekly across residential and light commercial jobs. The fixes range from simple dirt and draft issues to deeper failures in thermocouples, gas valves, and venting. Most homeowners can handle a basic relight safely, but when symptoms persist, a trained tech with the right tools makes the difference between a short-term reprieve and a reliable fix.
This guide distills the patterns we see in the field, with practical steps and the jb rooter and plumbing experts judgment calls that come from years of climbing into closets, garages, crawlspaces, and tight utility rooms. If you want to understand your heater, decide when to try a do‑it‑yourself step, and know when to call an expert, you are in the right place.
Why the pilot light matters more than it seems
Water heaters with standing pilots rely on a small, steady flame to ignite the main burner when the thermostat calls for heat. That flame needs clean combustion air, correct gas flow, and an intact sensor to prove the flame exists. If any piece in that chain is weak, the system protects itself by shutting down. The result looks like a fussy pilot, but the root cause can be fuel starvation, a failing safety sensor, a blocked flue, or even a thermostat malfunction. The symptoms overlap, which is why methodical troubleshooting pays off.
A quick example from last winter: a pilot that kept going out after windy nights. The homeowner suspected a bad thermocouple and had already replaced it. The real culprit was a downdraft through a poorly terminated vent cap. Twenty minutes on the roof, a proper cap with a wind band, and the pilot stayed lit all season.
Safety first, with real guardrails
Gas work demands respect. If you smell gas strongly, hear hissing from the appliance, or see soot buildup around the draft hood, stop and call your gas utility or licensed professionals immediately. Don’t flip light switches, don’t use open flames, and ventilate the area if it’s safe to do so. Ignoring warning signs is how small problems become headlines. Our insured emergency sewer repair team and emergency leak repair contractors handle water and sewer emergencies around the clock, and we apply the same urgency to gas-related calls that cross into unsafe territory.
Know your water heater type
Not all pilot lights are created equal. Most older atmospheric tanks use a standing pilot with a thermocouple. Newer models may use a spark igniter with a flame sensor, or a sealed combustion chamber with a view window and a piezo igniter. Some high-efficiency units skip the pilot entirely and use hot-surface or direct ignition. The troubleshooting logic overlaps, but details differ.
Look for the manufacturer label on the side of the tank. Note the brand, model, serial, BTU input, and year of manufacture. We keep a mental library of design quirks by brand and era. For example, a mid-2000s atmospheric heater often has a flame arrestor screen under the burner that clogs with lint and dust, starving the pilot for air. You can replace parts all day and still have a flame that lifts and sputters unless you clean that screen.
What a healthy pilot looks and sounds like
A stable pilot flame is blue, steady, and just long enough to wrap around the thermocouple or flame sensor tip by 3 to 8 millimeters. You should not see yellow tips licking away from the sensor. The sound should be a soft whisper, not a roar. If the pilot dances or pulls toward the back of the burner compartment, suspect a draft or an air supply issue. If it’s lazy and yellow, suspect dirt in the pilot orifice, a clogged air intake, or incomplete combustion due to restricted venting.
We measure pilot generator output with a multimeter if a flame looks marginal. A healthy thermocouple typically generates 25 to 35 millivolts under flame. Values below that often explain nuisance shutdowns, though the cause could be flame geometry rather than the thermocouple itself.
The quick checks you can do safely
Most homeowners can perform a basic relight and a few visual inspections. Done with care, these steps solve a meaningful slice of service calls, especially after a gas interruption or recent tank move.
- Confirm the gas control is set to Pilot and push the control knob in fully while igniting. Hold for 30 to 60 seconds to heat the thermocouple before releasing. If it goes out immediately upon release, repeat once. If it fails again, move to inspection. Check for drafts. Open garage doors, leaky access panels, and HVAC returns can steal flame from a pilot. Temporarily close nearby doors and vents. If the pilot holds under still air but fails when a fan runs, you’ve found a contributing factor. Inspect the combustion air path. Look for lint, pet hair, and dust mats under the tank, especially on flame arrestor screens. Vacuum gently around the perimeter and under the base without disassembling sealed components. Verify the flue is hot when the burner runs. If the pilot lights but the main burner produces lazy yellow flames and the draft hood spills warm air, you may have a blocked vent. Stop there and call a pro. Note the color and length of the pilot flame. Take a short video. A tech can often diagnose issues from that clip before arriving.
If you smell gas strongly at any point, stop and call. If your heater has an FVIR (flammable vapor ignition resistant) sealed chamber with screws and gaskets, do not remove panels unless the manufacturer’s manual explicitly instructs you to, since those seals matter for safety.
Common reasons a pilot won’t stay lit
We track failure modes across hundreds of visits each year. The same causes recur across brands and vintages.
Thermocouple fatigue. These slim sensors live in a hot zone and age out. We see them fail gradually, with pilots holding until a cold morning or failing after a small draft. Replacement is straightforward, but routing and securing the new lead matters. If it sits slightly out of the flame or picks up strain, you’ll be repeating the job.
Dirty pilot orifice. A tiny spider web or a grain of rust can shrink pilot output by half. Cleaning requires removing the pilot tube and gently clearing the orifice with appropriate tools. Poking with random wire often deforms the opening, which changes flame shape. We use a numbered tip cleaner and compressed air, with eye protection.
Weak gas control valve. Inside the thermostat-gas valve assembly are safeties and seats that can wear or stick. If the thermocouple tests healthy yet the valve won’t hold open, the valve could be at fault. We replace the entire valve rather than trying to nurse a compromised unit along.
Insufficient combustion air. Tight closets without proper louvered doors, heaters installed after weatherization, or new garage seals can starve a pilot. You’ll see sooting, lazy flame, and sometimes scorch marks. Cutting in proper combustion air openings, sized per code, fixes the root cause.
Vent problems. Birds love warm flue caps, and wind can defeat poor terminations. A vent out of plumb or assembled with too many elbows encourages backdrafting. We check draft with a smoke pencil at the hood, and we inspect the cap for obstructions.
Overheat and spill switches. Many heaters have one-shot thermal fuses or manual reset spill switches. If the heater experienced severe spillage once, the fuse may have opened. Replacing it without solving the draft problem is like taping over a warning light.
Water damage and corrosion. A slow leak above the burner can drip onto the pilot assembly. Corrosion on the bracket shifts the pilot angle just enough to miss the sensor. Fix the leak or replace the tank if the jacket is compromised.
When repair makes sense and when replacement wins
A fifteen-year-old tank with a failing gas valve, a rusted burner tray, and a history of pilot issues is a bad candidate for more parts. The combined cost of a valve, pilot assembly, and labor often approaches half the price of a new unit. If the tank also shows signs of sediment buildup and reduced recovery, we counsel replacement. Our certified water heater replacement team can swap a 40 or 50 gallon atmospheric unit same day in most cases, including code upgrades like flex gas connectors, seismic strapping, and expansion tanks where required.
On newer tanks with clean jackets, strong anodes, and isolated pilot issues, repair is usually the smart play. A thermocouple and pilot cleaning often return years of service. We quote both paths and explain the tradeoffs plainly, including energy efficiency gains with newer models. Sometimes the peace of mind of a fresh warranty tips the balance even if the old tank still has life.
Field scenarios that teach useful lessons
Wind-prone garages. A pilot that fails only on windy days often points to vent termination or garage door drafts. We might install a wind-resistant cap, extend the flue to proper height relative to rooflines, or add a simple draft baffle in the enclosure. Tiny tweaks, big changes.
Laundry room lint. Gas water heaters that share space with dryers collect lint on the intake screen. We have vacuumed enough felt off arrestor plates to knit a sweater. A quarterly clean keeps pilots stable and burners efficient. Our local plumbing maintenance company teams often pair this with dryer vent cleaning for a one-and-done visit.
Basement remodels. After air sealing and adding new doors, the once-adequate combustion air disappeared. The pilot grew lazy, the burner sooted, and a spill switch tripped. Cutting in high and low louvered grilles to adjacent spaces solved the problem without touching the heater.
Mobile homes and manufactured housing. These units often require specific sealed combustion models. A standard atmospheric tank with an open draft hood in a tight mobile home poses risks. If your pilot issues coincide with door and window changes, evaluate the appliance type. We advise compliant replacements and handle permitting.
Off-the-shelf thermocouples vs OEM. Universal kits work, but the bracket geometry matters. We carry both, and if the universal bracket places the tip 2 millimeters too far from the pilot cone, we finesse it with careful alignment. Getting that placement correct reduces callbacks dramatically.
Tools and measurements professionals bring
A practiced eye solves half the puzzle, but a few instruments close the loop. Draft gauges verify upward flow. Combustion analyzers reveal excess air and CO signatures when the main burner runs. A manometer tests inlet and outlet gas pressure, crucial when multiple appliances share a line. A multimeter or millivolt tester confirms thermocouple health under flame. Smoke pencils visualize spillage patterns. This data makes decisions objective. If line pressure sags when a furnace kicks on, your pilot may be an innocent bystander to a gas supply issue.
Our skilled plumbing maintenance experts arrive with the right kit and parts on the truck. A tidy set of screws organized by brand and era saves time when opening sealed chambers. Gaskets for common models prevent air leaks on reassembly. You get a clean repair rather than a patched one.
How maintenance prevents pilot headaches
Water heaters are often set-and-forget appliances until they aren’t. An annual tune helps. We vacuum dust from the intake, check the pilot flame and thermocouple output, inspect the vent, test the T&P valve, and drain a few gallons to pull sediment. In homes with mineral-heavy water, a flush every six months keeps scale off the burner and heat exchanger surfaces. That lowers stack temperature and improves efficiency, which indirectly helps pilot stability by keeping the flame environment clean.
If you run a small business, like a salon or café, hot water downtime hurts revenue. Our plumbing company with proven trust offers preventive service plans that include leak detection professional backflow prevention services, reliable pipe inspection contractor visits for suspect lines, and expert bathroom plumbing repair when fixtures start to misbehave. Bundling maintenance keeps costs predictable and reduces 3 a.m. surprises.
The step-by-step relight, simplified for common models
If your model uses a standard standing pilot with a push-button igniter, this sequence covers most cases. Always confirm with your manufacturer’s instructions printed on the tank.
- Turn the gas control knob to Off and wait five minutes to clear any residual gas. Do not skip the wait. Turn the knob to Pilot. Press and hold it down. While holding, press the igniter until you see the pilot flame through the window or open port. Continue holding the knob for 30 to 60 seconds. Release the knob gently. If the pilot stays lit, turn the control to On and set the temperature to a safe setting, typically around 120 F to 125 F for most households. Watch the main burner light. The flames should be mostly blue with small yellow tips. Check draft at the hood with a small strip of tissue. It should pull gently into the hood. If the pilot will not stay lit after two attempts, stop and schedule service. Repeated attempts can flood the chamber with gas or mask an underlying safety issue.
A quick note on temperature: 120 F protects most families from scalding risk while providing comfortable showers. Dialing higher than 130 F raises energy use and risk, though some homes with long lines or dishwashers that lack internal heaters prefer 125 to 130 F. If you need hotter water for sanitization, consider a thermostatic mixing valve at the heater.
When pilot problems hint at bigger plumbing needs
Plumbing systems age as a unit. A failing pilot on a 17-year-old tank may occur alongside galvanized piping that sheds rust, slow drains that suggest roots, or a cranky fill valve in a toilet that runs at night. While we are onsite, we often spot issues worth tackling before they escalate.
If you have recurrent sewer smells or backing up fixtures, our licensed sewer inspection company uses cameras to find the break or belly before it becomes a floor disaster. For slab homes with rising water bills and warm floor spots, our trusted slab leak detection team locates hidden leaks without tearing up the whole floor. Garbage disposals that jam or leak can be restored or replaced by our professional garbage disposal services, usually in under an hour. Toilets that wobble or ghost-flush at 2 a.m. benefit from affordable toilet repair specialists who carry wax rings, fill valves, and quality flappers on the truck. When drains collapse or corrode, our experienced drain replacement crews handle spot repairs or full runs, matching materials to code and budget. These services dovetail with reliable hot water, which is why we offer them under one roof.
Code, permits, and the quiet details that keep you safe
Swapping a thermocouple rarely requires a permit, but replacing a gas control valve or the entire water heater often does. Vent sizes, draft hood compatibility, earthquake strapping, sediment traps, and combustion air openings are not busywork. They are the guardrails that keep a simple appliance from becoming a hazard. We handle permits and inspections so the install meets code the first time. If a city inspector wants a minor change, we make it.
Backflow assemblies, common on commercial builds and some residential sprinkler systems, also need periodic testing. Our professional backflow prevention services keep you compliant and your potable water protected. It is all part of being a plumbing company with proven trust, one that solves the immediate issue and minds the bigger picture.
What a service visit looks like with JB Rooter and Plumbing Inc
On arrival, we listen first. When did the pilot start acting up? Did anything change recently, like a remodel, new appliances, or weather shifts? Then we run through a structured diagnostic: verify gas supply and pressure, confirm pilot and thermocouple function, evaluate combustion air, inspect venting, and test safety switches. We clean or replace what needs it, explain what we did, and show you flame characteristics before we leave. You should know what to watch for and when to call again.
If replacement is the smarter route, our certified water heater replacement team reviews tank types and sizes, recovery rates, warranty terms, and venting options. We can install standard atmospheric models, power vent units for challenging vent runs, or direct vent options where sealed combustion is required. We dispose of the old tank properly and leave the area cleaner than we found it.
If a related plumbing issue emerges during the visit, we can often address it on the spot. Our skilled plumbing maintenance experts carry materials for common fixes and coordinate with our reliable pipe inspection contractor teams when deeper diagnostics are needed. When emergencies strike after hours, our insured emergency sewer repair and emergency leak repair contractors are on call.
Practical tips to extend your water heater’s life
Water heaters rarely fail without sending signals first. Quiet gurgles, longer waits for hot water, discolored discharge from the drain valve, and pilot irregularities all hint at maintenance needs.
- Drain a few gallons quarterly to reduce sediment, especially if you hear popping when the burner runs. Keep the area around the heater clean and free of chemicals or solvents. Vapors can cause burner issues and paint the flame yellow. Replace a worn anode rod every 3 to 5 years in standard tanks, more often with very hard water. Test the T&P valve yearly by lifting the lever briefly. If it drips afterward, replace it. Keep the room ventilated appropriately. If you remodel, revisit combustion air openings with a pro.
These simple habits cost little and buy years of service. They also keep pilots happier by preserving clean combustion.
A note on energy, comfort, and the path forward
Pilot-equipped heaters do their job, but they sip gas year-round to keep that small flame lit. If you want to trim utility costs, a newer electronic ignition model or a heat pump water heater can make sense. We can compare operating costs based on your gas and electric rates. Occasionally the upfront premium pays back in three to seven years, especially in homes with high hot water use. If your pilot headaches are the nudge toward modernization, we will map the options without pressure.
When to stop tinkering and make the call
If the pilot lights but will not hold more than a second or two, if you see soot, if you have to relight weekly, or if the burner flames are lazy yellow with rolling tips, it is time for a professional evaluation. A water heater is a simple machine on the surface, yet the safety envelope is tight. We value homeowners who try the basics and then call before small faults become dangerous. That partnership keeps hot water steady and homes safe.
JB Rooter and Plumbing Inc stands ready to help with trusted hot water tank repair, from pilot light troubleshooting to full system replacement. We bring the same care to every job, whether we are adjusting a pilot, performing expert bathroom plumbing repair, or tackling experienced drain replacement on a tired line. If you need routine care, our local plumbing maintenance company can set a schedule that fits your home. If trouble pops up at midnight, our insured emergency sewer repair and emergency leak repair contractors pick up the phone.
Warm showers are nonnegotiable in a busy household. If your pilot keeps testing your patience, let us restore the quiet reliability you expect.