Water Heater Running Constantly? Here’s What You Need to Know8 min read

When we first moved to our new home (which is actually an older building), there was a lot to think about. We didn’t even think to check if the water heater was running constantly.

Luckily, we eventually realized there was a problem, but our first energy bill was a bit of a shocker. Hot water is a necessity, and because our boiler was providing it by converting cold water into hot water, we didn’t even question whether it was working or not: we just presumed it was all fine. 

It turns out that water heaters that constantly run typically have leaks, broken thermostats, faulty heating elements, sediment issues, or hot water loop problems in the supply chain.

You can fix the lightest water supply problem if it only requires hand tools, but most other cases require the professional services of a plumber.

This article has been expert reviewed by Mark Longhurst, a plumber with over 15 years of experience and owner of Pipe Smart. We take reliable information seriously, so look out for expert quotes in this article.

Why Is My Water Heater Running Constantly?

As always, the first step is knowing the root cause of the problem. I’ll give you a rundown of the most likely culprits:

Broken Thermostat

The thermostat in a water heater system indicates and switches the heating system in a house on or off as necessary. If broken, it may not turn off the boiler when the water reaches a specific temperature.

Water Heater Thermostat

Why is this an issue? Well, the boiler will stay on all the time, even if it’s already at the exact temperature you want. This leads to increased wear and tear on your boiler, causing it to wear out way more quickly than it should (as well as faucet temperature issues).  

You may also find that it impacts your radiators, and they may not heat up as well as they should.

Faulty Boiler

Faulty boilers are another common culprit that can cause a water heater to run constantly. The boiler heats the water inside the unit; if it’s damaged or broken, it can’t heat the water in an efficient way. This means your boiler will stay on to try and maintain the correct temperature.

So, why is this an issue? Mainly, this is going to hit your wallet pretty hard. A fault will usually require the services of a plumber, and if you don’t get it fixed, it could cause even more problems further down the line.

Sediment Buildup

Something people don’t often think about is sediment buildup.

Over a long period of time, minerals in the water rest at the bottom of the unit, creating a kind of sludgy layer of sediment. This residue can clog up the boiler, preventing it from running efficiently and making it work harder to heat the water.

The boiler may end up staying on all the time, even if the water is actually at the right temperature. 

Sediment buildup is a problem, too, because it can cause wear and tear, meaning you’re more likely to need to shell out for expensive repairs. You may even have to invest in a water heater replacement more quickly than you would have done otherwise.

Water Pressure Issues

Water pressure issues can be a problem for a whole bunch of reasons and can cause problems with your shower and sinks, too. Our old home had a lot of water pressure issues to deal with, and we found them to be a real headache.

If the water pressure in your home is too high, the boiler will have to work super hard to compensate to heat your water. This means it can keep running even if there’s no demand for hot water.

As I work with different types of water heating systems, I’m always keenly observing and sensing the water pressure in all parts of the system. Excessive pressure can strain the water heater, specifically the plumbing lines & equipment/devices that run all day long.

Mark Longhurst

The most obvious impact of this? Your energy bills. You’ll end up shelling out more money if your boiler is running constantly to compensate for pressure issues.


This is the problem I experienced, and it meant we had to call a plumber for a repair. Leaks can occur in the pipes or faucet, draining the unit of hot water, which then causes the boiler to keep running and can cause issues with water flow.

My bathroom faucet has a tendency to leak, and above all else, leaks can cause significant damage to your property.

The main issue with leaks is this: they can cause a lot of stress on the boiler and, if not caught quickly, can create more wear and tear. While shelling out the money isn’t the most fun thing to do, leaks need to be fixed by a plumber, or you may need to get your boiler replaced completely. 

The most notable problem that I’ve encountered with water heaters is leak and corrosion that might happen in your system as time goes by. I’ll regularly inspect the area around the water heater for any signs of leakage in floorings or walls, and corrosion in the plumbing lines. Addressing leaks promptly can prevent water pressure and temperature problems and more extensive issues.

Mark Longhurst

6 Steps to Fix Your Water Heater

Now that you’ve (hopefully) identified the problem, you can figure out how to fix it. It’s important to know that only light repairs should be attempted. If in doubt, call a plumber. They’re the experts, after all.

But here’s what I recommend if you want to tackle water heater failure:

Materials Needed

Bonus tip: make sure you get your towels ready first. If you start trying to tighten any leaks, water can flow out, and you don’t want to deal with a wet floor. (I learned this lesson the hard way.)

1. Turn off the Power and Water Supply

The most important step is this: turn off the power and water supply. It goes without saying that this is really crucial for your own safety.

To switch off the power, find the circuit breaker that controls the water heater and switch it off. Then, you can turn off the water supply by closing the valve near the water heater. 

I’ve had instances whereby when switching the system on, the circuit breaker trips immediately (tripping of breaker happens when the switch auto-toggles on the middle section of the circuit breaker and cuts off the power on that particular circuit). If this happens there might be a short-circuit in the electrical line or there is a grounded connection or wirings, better to consult a certified electrician to see your electrical line problem for your water heater.

Mark Longhurst

I’d recommend triple-checking that you’ve done this correctly before continuing.

2. Fix Any Leaks

Now that it’s safe, it’s time to hunt down a water heater leak. You can probably spot the obvious leaks right away. Check the outside for visible leaks or pools of water.

I’d recommend starting at the base, moving slowly to the top of the water heater, and then checking the back, particularly where the intake pipes connect to the tank. This can be tricky to see, but it’s a common culprit for leaks.

If you’ve found no leaks, it may be time to call a plumber, as you might need some specialized assistance.

3. Check the Water Pipes

There are two pipes that commonly leak water from a water heater; these are the pipes that deliver water in and take it out of the unit.

Any connections are weak points, and these are worth checking for dampness or trickles of water. You may be able to tighten these connections between the water pipes, and this could solve the problem.

In my experience, however, each water heater is a little different from the other. They all have different configurations of connections and pipes and threading, and this means that you may need specific advice or tools to make the repairs.

A good bit of gear to keep in your toolkit is pipe tape: it creates a secure connection between pipes and is thick, durable, and strong.

4. Inspect the Temperature Pressure Relief Valve

The temperature pressure relief valve vents pressure inside the unit. It is designed to prevent critical failures that can cause explosions, so you need to pay close attention to this.

If the valve is loose, your unit can start to leak at the point where the valve attaches to the tank. The valve is typically located on top of the water heater, and if you see a leak around the temperature pressure valve, then bingo – you’ve found the culprit.

I would say that it’s better to consult a certified plumber here. If it involves the valves or the pump, you need outside support. These are crucial, valuable parts of your water heater, and if you improperly fix them, it may cost you more money in the long run.

5. Flush the Tank to Remove Sediment Buildup

Sediment buildup inside the water heater tank significantly affects your unit’s ability to keep water hot. Sediment builds up over time, causing clogged pipes and less efficiency.

You can flush the tank to remove all sediments to resolve this issue. You may need to attach a hose to the drain valve at the base of the tank and let the water out until the water runs clear.

Each unit will have a different set of instructions for draining the tank and removing buildup. Consult your owner’s manual for the most accurate information and safety guidelines. It’s not worth taking the risk by messing around with this, in my opinion, unless you’re sure you know what you’re doing.

I always say if you don’t have the experience or feel uncomfortable performing the repair, contact a technician for additional assistance: it’s way better to do this than to attempt something you’re not confident about.

I always schedule periodic flushing of the tanks to remove sediments if there is no sediment filter present in the system. I also try to teach users how to flush their own tanks which is easier to do as long as they follow the safety measures before doing the flushing. These problems cause reduced efficiency of the heater and lead to overheating or other problems.

Mark Longhurst

Here’s a useful video I found on how to flush a water heater tank:

6. Inspect the Boiler

Another component to inspect is the boiler, as a damaged or broken component can cause your unit to stay on longer and drain your energy bills without you realizing.

Look for any visible damage or signs of wear and tear on the heating element. To inspect the heating element, turn off the power to the unit and remove the access panel.

You can use a multimeter to test the heating element for continuity. If there is no continuity, then it’s probably bad news: the heating element is likely damaged and needs to be replaced.

In my opinion, it’s better to call a certified plumber for this kind of issue: this may result in an explosion if not properly addressed by someone specialized, so it’s better not to take the risk.

When to Call a Professional

While there are a few measures you can take to fix common water heater issues, there are situations when it’s best to contact a professional. Here are some concerns to be aware of:

  • You are unsure how to proceed with any repairs or maintenance on your water heater.
  • You notice a leak in your hot water system, especially if it is coming from the tank itself.
  • The water heater makes unusual noises, such as popping or hissing sounds.
  • You smell gas coming from the water heater, which could indicate a gas leak.

Important note: if you do smell gas coming from the water heater, call a professional immediately. A certified plumbing service will be able to help with water heater repair.

The same goes if you don’t have the tools for these kinds of repairs: it may work out to be more cost-effective to get a plumber to look at it for you.

Hiring an expert for assistance ensures the problem is diagnosed and fixed correctly. Licensed plumbers have the knowledge and experience necessary to identify and repair complex water heater issues.

While I love to try to fix everything myself, I don’t suggest anyone goes down the DIY route if it’s not an easy problem to fix. DIY, in this case, can cause more problems and damage to the system, and you need a licensed professional to help.

Prevention and Maintenance Tips

Prevention is better than cure, right? Taking care of your water heater can stop these issues from cropping up in the future. Here are a few tips for water heater maintenance:

  • Installing a timer can help to reduce energy bills and prevent water heaters from running constantly.
  • Checking the temperature setting regularly can ensure that the water is heated to the desired temperature, which can also help to reduce energy bills.
  • Insulating the pipes can help to prevent heat loss and reduce the workload on the water heater, which can also help to lower energy bills.
  • Preventative Maintenance Service, which is a periodic water heater service conducted by the water heater installer, may prevent upcoming problems in the system, which drastically reduces the chance of having any problems with your water heater in the future.

I’ve got into the habit of doing these things by setting reminders on my phone. I often forget to do this stuff, but having an alarm pop up every now and then stops these little jobs from slipping through the cracks.

Lastly, having your water heater inspected and serviced by a licensed plumber at least once a year is recommended. A technician can check for issues and perform maintenance tasks such as flushing the tank, replacing the anode rod, and making necessary adjustments.

What Causes A Water Heater to Run Constantly: Key Takeaways

I really hope this article will help if, like us, you find yourself with a constantly running water heater with no idea how to fix it. You don’t want to be stuck with a huge energy bill like we were.

Here are the most common problems that can cause your hot water heater to run all the time:

  • Broken Thermostat: If the thermostat is broken, your water heater may run constantly even if the water is already at the right temperature
  • Faulty Boiler: A faulty boiler won’t be able to heat water efficiently, causing your energy bills to skyrocket
  • Sediment Buildup: Sediment build-up in the bottom of your water heater can cause clogging, which may make your water heater all the time
  • Water Pressure Issues: If you have water pressure problems in your home, you may find your water heater has to work hard to compensate
  • Leaks: Even small leaks can cause the water heater to keep filling up again and again, causing stress and wear and tear
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Hi, I'm Ed, and I run BuildFanatic! I enjoy providing the best possible information on a range of home improvement topics.

Mark Longhurst
Plumber at http://www.pipesmart.com.au/ | Website | + posts

Mark Longhurst is a professional plumber with over 15 years of experience, owns Pipesmart, and is our resident expert in all things plumbing.

Mark helps review plumbing-related articles for BuildFanatic to ensure we're providing our readers with the most accurate and updated advice.

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