Troubleshooting Strange Noises in a Water Heater

Within months of replacing a water heater, we started to hear some odd, popping noises. This was particularly annoying because our old water heater clearly had to be replaced but it had been quieter than our new one! Although we had a warranty, I didn’t look forward to calling a repairman and taking time to get the problem fixed. Luckily, some research and a couple of phone calls later, I was able to figure out how to diagnose and repair the water heater. Not only did this save money but we haven’t had serious issues with it since. Our water heater company had an employee who talked us through the situation and kept our warranty firmly in place. It was a win/win situation. There are some common causes, whether normal and abnormal, of water heater noises. If you have any doubt about what may be causing strange water heater noises, don’t take chances. Call a professional plumber or water heater repair person. Otherwise, you could run the risk of voiding your warranty – and you certainly don’t want to do that! But your warranty terms may allow you to diagnose and even fix some common problems on your own, saving time and money. If you want to try and diagnose popping, whistling or other noises coming from your water heater, here are some suggestions:

Step one – to diagnose water heater noises, make sure you are familiar with how your water heater works.

It really isn’t hard to find information about how water heaters work. Most water heaters have serial numbers or even website or phone numbers on the sides of them. If not, you have hopefully saved your service manual. If not, find the brand name of your heater and try searching for a website for your specific model of electric or gas water heater and try to find an online manual. Many are now easily found online.

I have also found one site which is extremely helpful as a general guide (but only a general guide) to understanding how water heaters work. It is called How Stuff Works and an illustration of a water heater, as well as a description about how they generally work, can be seen here but I’ve found that specific models have unique water heater problems. Even so, the site can be a great place to start, especially for visual types who like to see how things work. At the very least, you’ll get an explanation about what should be happening with normal water heaters and get familiar with basic parts like the heating elements, pressure relief valve, etc.

Important tip: you might find it helpful to refer back to the illustration at that site when I describe our own personal experiences in handling water heater noises.

Step two- before you try to diagnose strange water heater sounds, make sure you’ve followed some common safety tips.

I wouldn’t think of proceeding further without advising you to play it safe. Unless you are going to restrict yourself to looking at your water heater but not touching it, you need to take some safety precautions. If you have an electric power heater, you need to turn off the power to that heater. If you have a gas water heater, you should know how to turn off the control knob or valve that shuts off the gas. Don’t take a chance on getting electrocuted or having a gas explosion. A DIY project is simply not worth that risk. You may also need to shut off the water supply to the heater, depending on what you plan to do next to diagnose any strange water heater noises.

Step three- check your warranty and consider calling your water heater company to get permission to make repairs.

You don’t have to take this step, of course, and wary types may well feel that they’ll be told that they have to pay for service or a repair call. But that was not my experience. I was glad I made the call and verified that tinkering with my water heater would not void my warranty. I could then proceed to fix the cause of my water heater’s noise problem and get on with life.

Step four – in order to diagnose strange water heater noises, you really need to know which ones are normal

I’ll be honest – some normal water heater noises can sound alarmingly abnormal. The first time I heard our water heater make a loud popping sound, I nearly jumped across the room! But it turned out to be absolutely fine, nothing wrong with our heater. Normal noises can include a whooshing sound as the gas comes on in a gas water heater. Electric water heaters can also make noises as the water heats and parts of the heater expand or contract.

Small amounts of sediment in a water heater can also cause noise. I’ll explain how to flush out your water heater (below) but a certain amount of sediment will build up between flushing periods. They can cause some rattling or even rumbling sounds, temporary and not serious. Also, our water heater service person told us that certain clanging or clicking sounds could occur when the heater cooled off or started to heat up. Finally (as we learned all too soon) the sad reality is that some water heaters are just noisier than others, even when operating correctly.

Step five – know some common causes and ways to diagnose strange water heater noises. Find out if you can fix the problem yourself.

Just to be clear, you should have made sure your warranty is safe (and you have followed safety instructions for yourself as well) . You’ve figured out the basic parts of your water heater. If so, you are ready to proceed. However, I am going to repeat what I noted above: if in doubt, call a repair person.

Strange water heater noises – rumbling sounds

A very common cause or this problem is sediment in your water heater. These sounds can be absolutely normal but you should also be flushing out the sediment regularly, somewhere between every 3-6 months. If you have hard water, you may need to do this more often. To flush out sediment, simply take a hose and connect it to the drain valve. Before you let the water drain out, make sure you’ve turned off the power to your water heater and closed any inlet valves that would let extra water enter your heater. Then simply let the water drain out. At our home, we have to run a hose to the driveway but you may be lucky enough to have a drain closer than that.

You may need to let your heater fill up again and flush it a couple of times if you have lots of sediment.

Strange water heater sounds – loud popping or banging noises

These can be very frightening the first time you hear them. However, this can be caused by excess water pressure. So check your water pressure and see if it is too high before calling a repair person. Or call the person and ask them to help you fix this yourself. Another possible solution? Turn off the circuit breakers to your tank and wait for about 2 hours. Turn them back on, let the water reheat and see if the noise is gone. I’m not sure why this fixes some noises but it worked for us and I’m not arguing with success. We were also told to do this by a professional water service technician.

Strange water heater noises- the sound of running water does not stop

Our neighbor had this issue and the cause was the temperature or pressure relief valve. If yours is old, consider having it replaced.

Strange water heater sounds – hissing or whistling noises

While these can occur for a variety of normal reasons, I would strongly suggest you contact a repair person if you hear these sounds. While your heating elements could normally produce these noises, there could also be more serious causes, including a dangerous amount of pressure in your water heater. So I’d play it safe and make that call to a water heater repair person or professional plumber.

Warning signs of serious water heater problems

Although I can’t give a complete list of all potential dangers, obvious ones include a strong smell of gas. Actually, the gas usually has an extra substance in it to make it smell stronger. That is what you smell. But any gas smell should be cause for concern. If you see water dripping on the floor and you have an electric heater or electricity involved anywhere near your heater, stay back! Call for help and take appropriate safety precautions. If your water heater has a loose connection or a leaking tank, this may beyond the scope of a normal DIY (do it yourself) repair situation.