Are you scratching your head wondering how to test water heater thermostat? Well, I’m here to put your mind at ease and help you figure out what to do. Knowing how to check – and potentially change – the thermostat can be pretty tricky stuff, so let me run through a few things for ya.
There may be a simple answer! It could be that either the thermostat or heating element needs replacing. Dive into this post and we’ll guide you through inspecting and replacing the thermostat – it’s a lot easier than you’d think!
How Electric Water Heaters Heat Water
An electric water heater works hard to heat up the water so that we can enjoy those hot showers. It works by drawing in cold water from its tank and heating it up through a process of electrical resistance. As electricity flows through special resistance coils, energy is converted into heat and the now warmer water is pushed back into the tank for our use. With all that zapping of electricity, you’re sure to get a jumpin’ hot shower in no time!
Most electric water heaters have two heating components that switch on and off depending on the temperature of the water. If it drops below a certain point, they’ll kick into gear to warm it up again – their frequency quickening at higher temps. Although some might reach as high as sizzling 66°C (150°F), the industry standard is kept nice and comfortable at 120°F (49°C).
What to Do If Your Water Heater Isn't Heating
Potential Cause
Steps to Follow
Power outage or an electrical issue
Check if there’s a power outage in your area.
Make sure the water heater is plugged in and receiving power.
Check the circuit breaker or fuse box for any tripped breakers or blown fuses.
Reset the breaker or replace the fuse if necessary.
Gas supply issue (for gas heaters)
Ensure the gas supply valve is fully open.
Check if other gas appliances are working properly to determine if there’s a gas supply issue.
If you smell gas, turn off the gas supply immediately, leave the area, and contact a professional.
The pilot light is out (for gas water heaters)
Locate the pilot light assembly.
Follow the manufacturer’s instructions to relight the pilot light.
If the pilot light won’t stay lit or relight, there might be an issue with the thermocouple or gas valve. Contact a professional for assistance
Thermostat setting issue
Check the thermostat setting on the water heater.
Make sure it’s set to an appropriate temperature (usually around 120 degrees Fahrenheit or 49 degrees Celsius).
Adjust the thermostat if needed.
Sediment buildup
Over time, sediment can accumulate in the bottom of the water heater tank, affecting heating efficiency.
Drain the water heater to remove the sediment buildup. Refer to the manufacturer’s instructions for the proper procedure.
Regularly flush the water heater to prevent future sediment buildup.
Heating element (for electric water heaters)
Turn off the power to the water heater at the circuit breaker.
Test the heating element with a multimeter to check for continuity. If there’s no continuity, the heating element is likely faulty and needs to be replaced.
Consult a professional or manufacturer for guidance on replacing the heating element.
Thermostat or heating system malfunction
If none of the above steps resolve the issue, there might be a problem with the thermostat or heating system.
Contact a professional plumber or HVAC technician to diagnose and repair the problem.
Testing an Electric Water Heater Element with a Multimeter
Having hot water blues? Keep getting shut down by the reset button? Before we call it quits, let’s use a multimeter to check for “continuity” in each element and its corresponding thermostat. We’ll be able to find out if there are any elements that shorted out or didn’t have the right electrical continuity – any problems like this will need a component replacement.
How to Test an Electric Hot Water Heater Element
Double-check if the system has been wiped. If so, you can just reset it again – no biggie!
Unplug the wires from the thermostat and take a look around; you’ll see that everything’s connected.
Put one of the multimeter’s probes in contact with the left terminal, right next to the reset button.
Gently press the leftmost reset button terminal with the opposite end of the multimeter probe. Then, hold your breath and wait—cross your fingers that everything turns out okay! If the thermostat is working right, the multimeter should read close to zero. If it shows a temperature that’s way off from zero, though – bingo! – you’ve got a broken thermostat.
Alrighty, let’s try this again – take a deep breath and hop to it! Just run through that same test on all the terminals next to the big reset button. Connecting one wire to the main terminal, right next to the temp gauge, and then the other to the left heating element’s terminal will check out if the lower part of your thermostat is in good shape. You’re on your way!
If the water in the tank is cooler than what the thermostat’s target temp is, then it looks like we could expect a resistance reading of close to zero on the multimeter – just about.
Switch the bottom wire and shift it from the left to the right heating element. After that’s done, let’s use a continuity test and run a multimeter to check if it reads ‘zero.’
If the water in the tank is too hot for the thermostat to handle, it’s gotta go into reverse.
Jumping right in, let’s test the lower thermostat to see if the upper one is working correctly. Ready, set, go! If the lower one is on point, then we can be sure that all is in order with the upper one – fingers crossed!
Unplug the bottom thermostat – that ought to do the trick! Pulling the power source should get your air conditioning or heating off and running. Let’s give it a shot and see if it works!
The first lead is plugged into one terminal, while the second lead is hooked up to the other – easy-peasy!
If the water’s below the thermostat setting, your multimeter should be bringing in close to zero ohms—makes sense, right? So why not try it out and see for yourself?
If the temperature of the water’s too hot, according to the thermostat, the multimeter won’t be giving you an accurate reading. Know that if you go beyond your preset limit, any reading you get will be false. It really pays off to pay attention on those hot days!
Woah, talk about extreme opposites! If a thermostat was broken, you’d be lucky if it were showing the exact opposite of what the temperature is actually like!
Well, how can you tell if your thermostat is on the blink? It’s a common question, and the answer isn’t always easy. One of the first signs of a problem is if you keep adjusting it to no avail – like some kind of whack-a-mole game. You crank up the heat and a few minutes later, suddenly it feels way too cold again. If that sounds familiar, it’s definitely time to replace your thermostat!
When you turn up the heat, you might hear a soft clicking coming from your air ducts. Or, quickly pop your hand over a vent and see if you can feel any change in the temperature. Give it a minute or two to kick in; otherwise, it’s time to look into replacing that thermostat!
FAQS
How do I know if my thermostat is working properly?
If your higher thermostat is acting up and there’s still no hot water, it’s time to dial up a plumber. Before you do that, take a peek at the top thermostat – it might be the culprit. Or, even if the lower thermostat is busted, it could be resulting in longer wait times for hot water to come through!
What happens when your hot water heater's thermostat stops working?
Heating elements generate hot water, and each thermostat keeps them in check. But if they malfunction, trouble’s a-brewin’ – ’cause the heat source would keep running, which could cause the water to get way too toasty.
What’s the norm for water heater temps?
Without going over 120 degrees Fahrenheit, you can avoid scorching your water. But most folks prefer a slightly higher setting of 140 degrees. That’s too low for specialists’ liking though — because the chance of bacteria like Legionella that causes Legionnaires disease growing inside your water heater goes up when it drops below 120.
Conclusion
Looks like your hot water heater might be on the fritz if you’re stuck taking cold showers and washing dishes with lukewarm water. Don’t fret though, because testing a thermostat is easy as pie—all you need is a few basic household items. We have guided you through the necessary steps to test a water heater thermostat!
Hi everyone! My name is Jason, and I am the founder of HeaterWise.com. Having run my own business as a Heating Engineer for 21 years, I have picked up a few things along the way.
I wanted to create Heater Wise as a place where anyone could come, from far and wide, to find the information that they need.
I hope you will join us here at Heater Wise, to get started on your own journey, to expand your knowledge, and make the best heating choices for you and your family.
