Why Does My Tankless Water Heater Sound Like a Jet Engine?

tankless water heater sounds like jet engine

Is your water heater suddenly sounding like a jumbo jet revving up for takeoff? While some humming or soft ticks are normal operational sounds, loud rumbling or screeching likely signals trouble needing attention.

In this guide, we’ll explore common causes behind noisy tankless heaters and practical troubleshooting tips you can try before calling in an expert.

Getting familiar with typical water heater acoustics makes it easier to detect abnormal noises indicating potential issues. We’ll review what well-functioning units sound like, then contrast with disruptive sounds signaling sediment buildup, pressure fluctuations, leakages, or failing parts.

The good news is many problems can be addressed DIY-style through basic flushing and inspections.

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How Should a Hot Water Heater Sound?

Getting to know the usual sounds your water heater makes can help you recognize when something is off. Before we explore some of the abnormal noises, let’s first talk about what a healthy operation tends to sound like.

Being familiar with these normal sounds will make it easier to detect if your unit starts making unusual noises that could indicate a problem.

Normal Hot Water Heater Sounds

Water heaters are not entirely noiseless. There’s a certain degree of gentle noise that should be expected from all water heaters. These sounds are there to let you know that water is flowing properly, and the heating element is functioning as it should during the hot water-making process.

1. Humming

Your water heater will likely create a steady humming sound after cold water flows into it. This minor humming sound is no different from the noise a desktop computer CPU makes.

The humming sound is created when cool water mixes with the already-heated water in the tank. This normal sound subsides once the water reaches the set temperature. It’s recommended to set the temperature between 120°F and 140°F.

2. Ticking

Just like humming sounds, intermittent soft ticking sounds also indicate that your water heater is functioning properly.

The ticking sound you hear from a functioning water heater comes from small fluctuations in the water pressure levels when components like pipes and valves turn water flow on and off.

3. Crackling

If you hear crackling sounds fun your water heater during operation, know that it’s a normal sound. Crackling noises are more common in gas-powered water heaters compared to their electrical counterparts.

In gas-powered water heaters, burner condensation is the reason behind the crackling sound. When water droplets collect around the burner, they make gentle crackling sounds when heated during gas combustion.

Abnormal Hot Water Heater Sounds

While some background sounds like crackling, humming, etc., are normal, loud disruptive screeching or rumbling-like sounds are not. When you hear sounds like that, 99% of the time, it means something is off with your appliance.

1. Loud bubbling or rumbling

If you notice an ongoing loud bubbling or rumbling noise from your water heater, this could be a sign that excess sediment has built up inside over time. Hard water deposits and mineral accumulations are the culprits to consider here.

As minerals and hard water deposits build up over time, the water tries to force its way through layers of buildup – this can create pockets of steam that make loud bubbling or rumbling noises, similar to that of boiling water.

2. High-pitched screeching

A high-pitched noise coming from your water heater could mean there is too much pressure building up inside. This happens when pressure levels spike higher than normal, putting strain on the internal pipes and valves.

When that happens, the components in your unit will start vibrating rapidly, creating an uncomfortable squealing or screeching noise that continues until the pressure is lowered manually or relief valves open to release the excess strain.

3. Continuous loud noises

If you notice your water heater making loud noises like banging, knocking, or high-powered humming that continues on for a while, that typically signals an underlying issue. These units are not designed to be producing such disruptive noises continually at high volumes.

The cause is usually a malfunctioning part like a damaged heating element or broken motor. For example, if a heating coil comes loose and starts vibrating against the inner tank, it could create relentless banging sounds.

While the occasional gentle hum or tick from a water heater is normal, persistent racket signals the need for a service call. Loud disruptive clangs and sounds are the appliance’s way of letting you know something needs attention (or is amiss).

Related Article: Rinnai Water Heater Error Code 12

Causes and Solutions for Water Heaters That Sound Like Jet Engines

So far, you now know the sounds to expect from a normal functioning water heater and the sounds that tell you that there’s something wrong that needs checking.

So what if my tankless sounds like a jet engine? Is that considered a safe sound? The answer: it’s definitely not. The normal sounds from your water heaters are usually low and sometimes inaudible (typically between 49 and 65 decibels) except you are close to the heater. But when it sounds like a jet engine, that’s your water heater screaming for help.

In this section, we’ll look at the common causes behind this troubling sound and detailed troubleshooting steps you can take to resolve it.

1. Sediment Buildup

The inner workings of your on-demand water heater seem complex but simply involve heating elements rapidly warming water flow. Smooth operation relies on preserving free contact between flowing water and hot surfaces.

Over time, tiny mineral particles in hard water settle out, gradually accumulating in the water heater tank bottom as sediment deposits. Like clutter blocking floor space, these once-dissolved bits slowly form a physical barrier separating heating elements from fresh water.

Suddenly, the heating components must work exponentially harder trying to transmit heat through the invisible mineral wall to warm incoming water. All this strained effort causes excess vibration and turbulence, transforming the once-smooth flow into bubbling, crackling chaos. The resulting ruckus easily permeates walls, amplifying in intensity as the sediment blockade thickens. Before you know it, formerly gentle water-heating sounds become an intolerable jet engine imitation!

How to Fix Sediment Buildup

The most effective way to handle sediment accumulation is by flushing the water heater thoroughly on a regular basis. Flushing helps eliminate mineral deposits, debris, and corrosion particles clogging the system.

Follow this process to flush out sediment properly:

  1. Turn off the power supply to your water heating unit and shut off the gas lines or unplug electric connections. For gas-powered heaters, reduce the temperature settings to vacation or pilot.
  2. Connect a garden hose to the drain valve located at the bottom of the tank. Make sure it can handle high temperatures.
  3. Place the other end of the hose outside to safely drain the hot water. Make sure the hose is securely connected. You can secure it by gently screwing one end into the drain stopper.
  4. Open the pressure relief valve or a hot water tap to allow air entry into the tank for rapid water drainage.
  5. Use a screwdriver to open the drain valve slowly. When you do, sediment-laden hot water will begin draining out.
  6. After complete drainage, close the drain valve. Introduce short bursts of cold water to agitate sediment. Allow the cold-water intake to stay in the tank for 20 to 30 seconds in total.
  7. Open the drain valve to flush out stirred sediment until the water runs clear.
  8. Repeat the flushing process thoroughly 2-3 times to remove all traces of sediment.
  9. Finally, close all valves/taps and restart the heater as per manufacturer guidelines.

Remember to flush the tank 2-3 times per year depending on your water hardness. Seek professional assistance if jet engine noise persists even after extensive flushing.

2. Unreliable Water Pressure

Do you know that inconsistent or fluctuating water pressure entering your water heater can make it produce sounds similar to that of a jet engine? If you didn’t, now you do.

If the incoming water pressure rises and falls repeatedly, it causes the internal pipes and components to vibrate intensely. And when that happens, things like solenoid valves, internal tubing, and heat exchangers will rattle loudly.

Much like an aircraft engine, this vibration results in an irritating high-pitched screeching noise coming from the unit. And as the water pressure continues to increase, the noise it produces increases as well.

Excessive water pressure puts undue strain on connections and components that are not designed to handle such intensities. It can degrade parts quicker and adversely impact heating capability and efficiency. Pressure spikes can also make temperature regulation erratic.

How to Fix Unreliable Water Pressure

The main solution here is installing a reliable pressure regulator valve on the supply line to maintain a steady 50-60 PSI at all times. Intermittent pressure changes should not exceed ± 10 PSI for optimal operation.

Follow this process to properly install a pressure regulator valve on your water heater:

  1. Locate the main water supply line and shut-off valve entering the home. The external shut-off valve must be completely closed.
  2. Identify an appropriate location to install the pressure regulator along the supply line. Ensure adequate straight pipe sections.
  3. Purchase a pressure regulating valve suited for whole house application with appropriate length and diameter. Metal is better.
  4. If needed, cut the supply line keeping necessary by-pass space to fit the valve conveniently.
  5. Use threaded adaptors if sizes don’t match. Apply thread seal tape to prevent leaks.
  6. Mount the pressure regulator valve vertically or horizontally following manufacturer instructions.
  7. Slowly turn on the main supply valve checking for leaks. Set the pressure regulator to 50 psi.
  8. Allow your water heater to operate for 20 minutes and confirm optimal pressure.
  9. If still fluctuating, small adjustments to the regulator spring tension screw can stabilize pressure.

Consider professional help with selecting and fitting the most suitable pressure regulator for best results. After installing the pressure regulator, endeavor to inspect it annually.

If regulating devices are unable to normalize pressures, the internal assemblage may need upgrading with industrial-grade parts rated for higher pressures.

3. Leakages

Leakages from valves, pipes, or tank corrosion can contribute to sizzling jet engine-like noises from water heaters.

As water or steam escapes through cracks and openings in the water heater system, it turns from liquid to vapor when hitting adjacent heated surfaces. This vaporization or flashing into steam causes a sharp hissing or sizzling sound.

Even small high-pressure leaks through minute openings can generate sufficient turbulence and velocities to induce vibrations and noise. The sounds get amplified within the closed water heater housing assembly.

How to Fix Leakages

To fix a leaky water heater and stop the jet engine-like sound you keep hearing, do the following:

  1. Carefully inspect valves, pipe joints, tanks, and gaskets for water accumulation, moisture, or corrosion indicating the source of the leak.
  2. Shut off inlet and outlet water lines and switch off the heat source to minimize leakage while working.
  3. Gently separate defective parts or segments of piping needing replacement or resealing. Avoid damaging utility lines.
  4. Use a wire brush and emery cloth to smooth out corrosion pits as well as imperfections needing filler treatment. Cut out ragged sections.
  5. Apply plumber’s putty, Teflon tape, or pipe thread paste for threaded joints. Torque appropriately without cracking flanges. Use rubber/polymer gaskets with tank segments bolted tightly at leaks.
  6. For damaged pressure valves, and corroded fittings/tanks, substitute with high-temperature parts that meet codes for durability.
  7. Monitor hot water usage cycles observing all locations for potential weak points releaking. Repeat fixes as necessary.
  8. Wrap insulation tightly around repaired piping and valves to minimize heat damage.

4. Obstructions

Another contributor to the disruptive jet engine noise coming from water heaters is some form of obstruction within the unit. In overextended operation, residue in the form of soot and combustion byproducts can gradually build up inside the combustion chamber.

This soot accumulation is more common around the main burner element of gas-powered tankless heaters. Excess debris like mud, dust, and lint can also amass internally over time, attracted by static charge. Even small nests constructed by insects like wasps or mud daubers can materialize unexpectedly.

Those obstructions accumulating in the water heater affect the smooth airflow around the burner assembly or the consistency of gas flow to the burner. This disruption in airflow/gas flow creates turbulence and instability during heating.

Much like an aircraft engine facing airflow resistance, obstructions in water heaters result in loud rumbling noises. If left unchecked, the unsteady heating can damage internal components and piping due to overheating.

How to Fix Obstructions

The solution lies in periodic inspection and careful cleaning of the combustion chamber. To tackle obstructions in water heaters, do the following:

  1. Switch off the gas line and unplug the heating unit. Allow adequate cooling time before opening internal compartments.
  2. Gain access to the combustion chamber and burner assembly area by removing exterior panels. Be gentle with wires and tubing.
  3. Use bright flashlights at multiple angles to visually identify all debris, soot deposits, mud formations, etc.
  4. Carefully use soft-bristle brushes and vacuum nozzles specially designed to capture dry particulate matter to clear surfaces.
  5. You can use damp lint-free microfiber cloths to wipe down surfaces cleanly after loosening debris. Cotton swabs can be used to reach small spaces.
  6. Check for any removable parts like gas valves, piping, and fittings for nests or soot accumulation. Clean thoroughly before reassembly.
  7. Ensure all passages, holes, and ventilation ports are totally free of obstructions and properly aligned before closure.
  8. Here is a rewrite of that passage in a friendly, professional tone:
  9. Turn on your water heater and allow it to complete 2-3 full heating cycles to warm up properly. This allows time for any leaks to potentially develop. Then, carefully check the combustion chamber and exhaust areas for leaks.
  10. Consult technicians if additional corrosion, damages, or leaks are observed that require component replacement.

With this detailed cleaning procedure, you should be able to remove most debris obstructions and restore smooth airflow and gas flow to stop irritating rumbling noises. However, do exercise caution and consider professional assistance if it seems complex.

5. Pressure Relief Valve Issues

The pressure relief valve on water heaters has an important purpose. The pressure relief valve is typically located on the upper section of the water heater, and it is designed to automatically release excess pressure buildup within the tank to prevent dangerous explosions.

However, an improperly seated, faulty or worn-out pressure relief valve may fail to seal completely after releasing high pressure buildups. This results in water and steam continuing to escape through the unsealed valve opening.

The high velocity discharge through this small opening generates a screeching resonant noise similar to that of a jet engine. The sound will persist until the leaky valve is replaced or reseated through repair.

How to Fix Pressure Relief Valves

To replace a faulty pressure relief valve, do the following:

  1. Shut off the electric circuit breaker or gas valve first before any work. This removes risks of burns or electrical hazards during repair.
  2. Attach a garden hose to the drain spigot and route it to a suitable ground area outdoors. Open the drain valve until water runs clear to remove sediment. Let some water remain in the bottom to keep components submerged.
  3. Note the PSI rating, BTU rating, and valve thread size to buy an appropriate replacement. Getting identical pressure relief specs prevents future operation issues.
  4. Using an adjustable wrench, detach the outlet drainpipe attached to the valve inlet first. Then turn the valve counterclockwise to fully unscrew it off the tank.
  5. Apply plumber’s putty, Teflon tape, pipe dope, or pipe thread paste for threaded joints. Ensure the tape fully seals the thread to prevent leaks. Briefly test the lever to ensure smooth operation.
  6. Screw in the replacement valve clockwise until hand tight and a further quarter turn more using the wrench. Do not over-tighten to avoid valve housing cracks.
  7. Seal off with additional tape and reattach the drain outlet pipe to direct discharge away from electrical components safely during release.

If done correctly, the lever should now discharge water smoothly and the jet engine noise should no longer persist with the replaced optimized valve securely containing internal tank pressures.

6. Mechanical Issues

Faulty mechanical components can also make your water heater mimic jet engine sounds. This is common with malfunctioning burners in gas-powered units or damaged heating elements in the electrical variant.

For gas-powered water heaters, the gas valves, pilot assemblies, and burners work in unison to ignite and transport heating gas like propane or natural gas. If the gas valve sticks, burner ports get blocked, or the pilot light goes off, it affects combustion.

When that happens (i.e., burner ports get blocked or pilot lights go off), it creates misfires, backfires, or abnormal fluttering sounds similar to a sputtering jet engine.

For electric water heaters, loose wiring or voltage fluctuations can make electric heating elements deform or dislodge slightly. So water flows over these incorrectly positioned elements, it makes loud tapping, screeching noises similar to an aircraft turbine gone haywire.

Additionally, worn-out internal components like circulation pumps, inlet water valves, and pressure relief valves also cause rumbling vibrations due to imbalance, inadequate mounting, or misalignment.

How to Fix Mechanical Issues

For mechanical issues, you need to inspect individual parts and replace whatever needs replacing. Gas valves, thermocouples, and pilot tubes may need cleaning or adjustments for optimized combustion. Also, make sure that the heating element is properly aligned.

Here is a detailed step-by-step process for addressing mechanical issues in water heaters:

  1. Shut off gas lines/electricity and allow the system to cool before handling interior parts.
  2. Consult your technical manual to identify removable panels granting access to internal mechanical components.
  3. Inspect wiring, mountings, and ignition parts closely for any visible damage, wearing out, or fatigue signs.
  4. Check gas valves, and lines for grime deposits, or misalignments affecting smooth fuel flow to the burner.
  5. Examine heating elements for calcification, and scaling causing misplaced contact.
  6. Monitor circulation pumps and motorized valves for abnormal vibrations indicating imminent failure.
  7. Record anomalies observed and cross-verify against replacement procedures given in product manuals.
  8. Order/purchase identical replacement parts from authorized dealers ready for substitution.
  9. De-mount the defective part carefully without damaging nearby components.
  10. Clean the mounting base area completely before seating the replacement part.
  11. Install a new part that matches all physical and electrical interfaces accurately.
  12. Restore insulation and panels back properly after calibration if needed.
  13. Run observation checks first before resuming full operation.

Note: DIY repairs are not advised because of the intricacies involved unless you have sufficient expertise. Otherwise, professional assistance is highly recommended.

Preventative Care for Water Heaters

Do you want your water heaters operating for many years without problems? Then performing regular preventative maintenance is a must. This involves flushing, component checks, and professional tune-ups.

Annual Flushing

Over time, mineral deposits and sediment can build up inside the tankless unit. It’s important to flush these out regularly, just as you would descale a coffee machine. Following the manufacturer’s recommendations for draining, spraying clean water bursts, and repeating clears out accumulated gunk and keeps water flowing efficiently across the heating elements.

Checking Anode Rod and Valves

An unassuming part called an anode rod attracts corrosion away from critical components inside the tankless unit. Check this sacrificial part twice a year and replace when worn over 50%. This buys full protection for the heater. Also, inspect pressure relief valves monthly to ensure safe regulation.

Professional Inspections/Tuning

Annual professional tune-ups detect early part wear, optimize calibrations, and dial in peak performance. Technicians can handle the dirty work while you enjoy long-lasting, disruption-free operation.

When to Call a Professional for Noisy Water Heater

While it’s possible to handle some troubleshooting measures by yourself, it’s important to know when to leave it for experts especially when it has to do with intricate repairs or safety concerns.

So how can you tell them apart? A problem that requires professional assistance from one you can handle alone?

Here are a few pointers that’ll guide you:

Recurring Problems After DIY Efforts

This is basically a no-brainer. If after trying all the tips and fixes yourself; the problem is still there, then it could mean that you have been doing it wrong or there’s something you are not doing or have missed.

In this case, instead of trying to figure out what you are not doing right, it’ll save you time and energy to just hire an expert technician to have a look at your appliance.

Complex Repairs

Not all repairs are simple. Some are complex and require technical knowledge that only experts seem to know. For example, a loose plumbing connection that’s spewing hot water and steam demands prompt welding or sealing injection – a feat technicians or professionals can handle.

Aside from that, it’s dangerous to try to handle complex high-pressure equipment without proper skills or gear because you risk harming yourself. You could get injured from gases, fires, or tank explosions. Whereas certified professionals are trained to handle such equipment safely.


The sudden deafening roar of your normally quiet water heater can cause alarm. But with some thoughtful troubleshooting, disruptive noises can usually be promptly resolved and peace restored.

As a first response, try basic DIY remedies like flushing or inspections. However, if the decibel level remains jet-engine-like despite your best efforts, be proactive – immediately call in a trained professional before the issue escalates. Timely expert intervention can solve intricate problems safely.

Even more vital than reactive troubleshooting is cultivating consistent preventative maintenance habits. Adopting annual flushes and component checks as habitual upkeep forms a critical line of defense, catching small problems before they become huge headaches. Think of it as routine dental cleanings for your water heater – not glamorous but well worth the minor time investment.

With some attentiveness and care, you can have your water heater humming along normally for years to come. No more unpleasant Boeing 747 imitations disturbing your home! Now you have the know-how to troubleshoot noises effectively and keep your unit in tip-top shape.

Related: Water Heater Beeping

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