It’s normal for all tankless water heaters to produce wide variety of noises so don’t fret that easily. The first thing you should check is the level of the sound and it must be on its usual level which is less than 90 decibels. You may use a decibel meter to know how loud your water heater is. There is even an app called SoundLevel which you can use to measure the decibel output.
Although the noises from your water heater is nothing to worry about, there are instances when it indicates a problem. You should be perceptive enough to identify the noises so that you can detect early warnings of trouble. Here are some typical noises you may hear from your water heater and the possible causes for such:
Varied Tankless Water Heater Noises And Their Causes
You can hear these sounds when flushing your toilet or even when you are not using your water heater and the source maybe a created vacuum when another source is siphoning water from the pipeline.
This sound is similar to a boiling kettle about to explode or venting once in a while. There are two possible sources of these sounds. First, these are produced when the sediments on the bottom, essentially mud, periodically releases bubbles. These sediments are a mixture of rust and calcium carbonate along with trace minerals from your drinking water and a buildup of sediment in the tank causes the bottom to overheat and the water to boil.
The second sign of this noise is overheated water. Because the sediment insulates the interior thermostat from the water, it overheats the water because it can’t determine the true temperature of the water.
If your water heater is too hot, it could be rumbling because the water is boiling extremely hot that it’s likely to explode. If the water is approaching its boiling point, its tendency is to rumble due to the roiling boil until the pressure relief valve literally sets off steam. The overheating can be due to a broken thermostat, the control board isn’t reading it right or there is sediment around the heating elements so it overheats until it boils up and the unit recognizes that it is hot.
A gas type water heater rumbles on the other hand because of uneven flame, turning on and off when the unit has poor combustion, along with the usual muddy mess.
This sound is also similar to the sound of a kettle or a whistle requiring a smaller opening. A simple reason for this noise is the bad scaling in the water heater which block the gas flow or other valves. There are still a lot of possible causes such as the vibration induced by the gas flow to the heater, a blockage in the line and squealing as the gas pushes through a narrower pipe, a deformation in the gas jets or vibrations in the pipe because the blockage is upstream near the gas meter.
You may hear those beeping sounds to warn you that your water heater has been shut off or there is a water or gas leak due to an electrical problem. These sounds may also be a pressure warning since hot water heaters are essentially pressurized boilers. This might also be due to the temperature sensor detecting that the unit could be getting hot because the elements may be overheating the water
If your water heater has leak detector, you may hear this sound to warn you that your unit is dripping. Your temperature sensor can also produce this sound when your unit is overheating to let you know that the temperature needs to be turned down.
The hissing noise can have three causes: 1. the pressure relief valve that’s just releasing some excess pressure; 2.a water leak or 3. if you have a swamp cooler, their copper pipes transfer noise of the cooler refilling itself.
This noise is caused by the friction of water that is continuously flowing around the element which is vertically aligned with the tank of your water heater.
This sound is your unit’s pressure valve releasing excess pressure or a crack somewhere that blows or sucks air out. Keep in mind that this sound may only be heard when you are using the unit. One way of checking is to turn your water on. If air comes out followed by water, then the air is being pushed through the pipe, but if there’s no air coming out, then your pipes are dirty and need to be cleaned.
If the noise however only comes out from the water heater, it might be water that’s forced through nozzle into the heater.
As the metal ages on exposure to hot water, it can rust and form a layer in the tank, and calcium and rust from the tap water accumulates over time and line inside the water tank. The water around the heating element gets hot but doesn’t quite circulate as freely as intended so it bubbles, burbles and gurgles as it escapes past the sediment toward the top.
This noise is caused again by calcium buildup in the water heater. Overtime, calcium deposits in your unit and can cause the knocking noise.
Check if the sound you hear is from a purging water softener and cleaning itself, if not, this is still a normal sound created as pipes expand and contract under the flow of hot water through them. If the noise is not from these two sources, it might be a water leak, and bubbling is making a sound as air bubbles up. Banging occurs as water heats up beneath a layer of sediment before bubbling up and rising through the mud. Thermal cycling can also cause banging in your pipes and in your water heater.
These sounds may be because of normal temperature changes. This can also be due to problems with the temperature sensor or control board. It causes the unit to overheat because the temperature sensor is not flat against the body, thus, it expands fast as it heats up and contracts when the unit gets too hot. The rattling sounds are actually a pressure differential in the water pipes to the water heater and not the unit itself. These sounds can also be mistaken to the sounds of the water softener.
Vibrating and Echoing Noise
These noises may originate from how your water heater is installed. Your unit could create vibrations if this is fixed against your wall because it can pound against the wall when turned on. On the other hand, echoes are produced if the water heater is installed within a protected box.
Solutions To Reduce Or Eliminate The Water Heater Noise
There are simple solutions that can help you resolve the noise problems of your water heater. Here are some of them:
- Popping Noise. Simply flush your water heater regularly to remove the sediments by completely draining it; however, if you have a gas water heater, you have to make sure that the gas valve is set to pilot so that the burners don’t come on while you are draining the water heater.
- Rumbling Noise. A temporary solution would be draining the water heater. Permanent solutions can be checking the thermostat and heating elements in an electric type water heater while checking the gas burners in a gas powered type.
- Squealing Noise. Try descaling the heat exchanger, burner or valves.
- Beeping Noise. Turn off the thermostat down and check.
- Chirping Noise. Change the batteries of your water heater.
- Hissing Noise. Check if your water meter spins unusually to check for water leak
- Humming Noise. Slightly tighten the element to correct this problem.
- Gurgling Noise. Flush your water heater and drain it all away to remove the sediments but ensure that your water heater is turned off and cooled down before doing this. You can also consider having a water softener to reduce the rust and calcium deposits.
- Knocking Noise. If your water heater is a gas type, you just have to turn it off and let the water drain out. If yours is an electric type, the first thing to do is to turn off the circuit, go to the breaker panel and make sure that the power is turned off to the unit; ensure that all the water is turned off to the home too. Then, get a bucket and drain your water heater making sure that all of the old water is out of the heater. You should use a shop vac to clean the spout and mop up any dripping water. Then, turn the water heater on and let it slowly fill; turn on a small outside spigot and make sure that the water heater supply in the heater gets to a steady and constant pressure. Finally, check if everything looks good to go and let it warm a bit.
- Vibrating and Echoing Noise. You can place a rubber mat or a mat between the wall and the water heater to absorb the sounds. Another solution is to insulate the box through an audio insulation product like the Dynomat.
- Whistling Noise. Clean the pipes frequently or try to fix them by replacing the old pipes.
If the solutions I give above for squealing, chirping, hissing and beeping noises do not fix the problem, the best thing to do is to check your manual or your manufacturer’s websites or you may let your manufacturer check the unit. All other noises such as rattling and banging require a professional plumber immediately to fix the problem. If all else fails, I assume that a unit replacement can be the best solution to your problem.
Generally speaking, tankless water heaters have lower chances of producing strange noises compared to tank models, yet it can get you some trouble. To prevent this, keep in mind that the simplest yet effective means is care and regular maintenance. If all your DIYs fail and you need assistance in helping with the noise problems, you may call your contractor or the plumber who installed your water heater to do their inspections and they will gladly assist you.