People have become accustomed to the convenience of having hot water in their homes. What most don’t realize is that a water heater can be a ticking time bomb waiting to explode. A neglected water heater could explode destroying their home in the process.
So can a water heater really explode? Electric and gas water heaters can explode if the pressure inside the tank is too high, failure of the temperature & pressure relief valve, or improper installation. With gas water heaters, flammable vapors or a gas leak can cause an explosion if a spark were to ignite the gas or flammable vapors.
The risk of explosion in modern water heaters is minimized through various safety features. However, most water heaters are not maintained well and the risk is still present and very real.
Modern water heaters are equipped with a safety feature called the Temperature & Pressure Relief Valve (T&P Valve). These valves require service to stay in proper working condition.
In this article we will examine:
3 Main Causes of Water Heater Explosions
There are three main causes of water heater explosions. These are high pressure, gas leaks, and improper installation. Let’s look closer at each of these.
High pressure inside the water heater can affect both gas and electric water heaters. High pressure occurs when the water inside the tank is heated. As the water heats up it expands building pressure inside the tank.
So what can cause high pressure to buildup inside the tank:
If water pressure inside the tank becomes too high it is released through a safety feature called the temperature & pressure relief valve or T&P valve. All modern water heaters are equipped with this safety feature. However, some older water heaters do not have this feature.
If the temperature and pressure relief valve fails or is blocked the pressure has no way to release resulting in your water heater eventually blowing up. As the water inside the water heater heats up it begins to expand. If the pressure from water expansions and gets too high the T&P valve opens to release pressure.
The high limit switch is a large red button located above the upper thermostat. If the thermostat is not regulating power to the heating elements, the water temperature will continue to rise to an unsafe level. The high limit switch will trip to cut power to the water heater thermostat and heating element.
The high limit switch located on the upper thermostat and is designed to trip in the event water inside the water heater exceeds 180 degrees. However, if the high limit switch were to fail to trip, the pressure inside the water heater could cause the water heater to explode due to increased pressure.
This is a highly unlikely scenario, as it would take a 1-2 punch of the high limit switch failure and the failure (or blocked) temperature and pressure relief valve to occur at the same time. This is a highly unlikely scenario. However, older water heaters may lack one or both of these safety features.
As your water heater ages, minerals deposits in hard water begin to buildup inside the tank. This sediment settles at the bottom of the tank. Left unattended, this sediment hardens and will eventually corrode the inner lining, thus weakening the walls of the water heater.
As the walls inside the water heater tank weaken they become susceptible to explosions even under normal pressure levels that may not trigger the T&P valve or high limit switch.
Fortunately, with routine water heater maintenance, you can solve these problems and even double the lifespan of your water heater. See our article Water Heater Maintenance Tips to 2X Your Tanks Lifespan.
This only affects natural gas or propane-powered water heaters. Electric water heaters do not have a gas supply and do not utilize open flames to heat water.
Gas and propane-powered water heaters have an incoming gas line, internal gas lines, and fittings where gas leaks can develop. A gas leak can be identified by a "rotten egg" smell coming from around the bottom of the water heater.
Natural gas and propane actually is colorless and odorless gas. A harmless chemical called mercaptan is added to give gas a distinctive "rotten egg" smell. This helps homeowners identify when a gas leak is present.
If a gas leak develops in or around the water heater, even a small ignition flame or electrical spark can ignite the gas causing a massive explosion.
The same is true for other flammable liquids often stored in garages like gasoline, kerosene, paint thinner, and other solvents which can be ignited accidentally by the pilot light of a gas water heater.
All gas or propane water heaters should have a gas detector nearby. We recommend the Kidde AC Plug-in Carbon Monoxide and Explosive Gas Detector Alarm.
Many homeowners like doing things themselves. It's good to save money on home projects. However, unless you have plumbing experience you should leave water heater installations to a licensed plumber.
Some of the improper installations we see include:
The number one warning sign that your water heater could explode is a leaky T&P Valve. When too much pressure builds inside the tank the temperature & pressure relief valve can discharge hot water. A leaky valve or a valve that routinely discharges is a tell-tell sign a problem exists.
This T&P valve will leak due to proper operation if too much pressure exists inside the tank. If you see this valve leaking or routinely discharging water you should immediately have the water heater serviced by a licensed plumber. You may need to lower the temperature setting or replace the T&P valve.
If you have a gas water heater and have a rotten egg smell around the outside of the water heater you likely have a gas leak.
Natural gas and propane have a sulfur or rotten egg type smell. This is done so on purpose so that in the event a gas leak occurs it can easily be detected before an explosion occurs. The odor you smell is ethyl mercaptan which is added to natural gas and propane to make the gas detectable by smell.
If you suspect your water heater has a gas leak you should immediately turn the gas off to the water heater and call in a licensed plumber to inspect and make any necessary repairs.
Unlike natural gas and propane gas, carbon monoxide gas is a colorless, odorless gas that is a by-product of the combustion process. This gas is extremely dangerous and can only be detected by specialized equipment. You can't see it or smell it. Carbon monoxide can cause sickness, debilitating injury, and even death.
Insider's Tip: Consider investing in an Explosive Gas Detector to install near your gas water heater. The Kidde AC Plug-in Carbon Monoxide and Explosive Gas Detector Alarm provides protection against Natural Gas, Propane Gas, and Carbon Monoxide. These explosive gas detectors are inexpensive and easy to install.
Gurgling, knocking, and popping sounds from inside the water heater are a sign that sediment has built up and hardened inside the tank. These sounds are caused by the water becoming trapped under sediment. As the water heats up and expands the hardened sediment moves around inside the water heater.
One of the causes is when the anode rod, a sacrificial rod located inside the water heater, has been eaten away by acidic sediment inside the tank. Without a line of defense, the harsh sediment begins to attack the internal tank. This, in turn, weakens the internal tank making it more susceptible to an explosion from increases in pressure inside the water heater.
Speaking of anode rods, if your hot water smells like “rotten eggs”, the most likely cause is anaerobic bacteria present inside the water heater that reacts with sulfur, magnesium, and aluminum sacrificial anode rods inside the water heater. As the anode rod deteriorates, hydrogen sulfide gas is produced creating a rotten egg smell in the hot water supply.
If your hot water smells bad, the sacrificial anode rod is likely completely eaten away. Once the sacrificial anode rod is completely sacrificed, minerals in hard water begin to attack the inner lining of the water heater.
This creates weak spots in your water heater. These weak spots can rupture under high pressure inside the tank even if it is within the boundaries of the T&P valve or high limit switch.
There are several ways that you can prevent your water heater from exploding. The number one line of defense is proper routine maintenance. Let’s explore some of the actions you can take to protect your water heater and property.
Water heaters require routine draining and flushing as part of the water heaters' routine maintenance. This maintenance is relatively easy to do but is often overlooked by homeowners.
Draining and flushing your water heater removes sediment that has built up inside the internal tank. This sediment needs to be removed to prevent the internal tank from deteriorating.
It is recommended that draining and flushing your water heater should be done on an annual basis. The process is fairly simple and takes about two hours of your time.
For details on water heater maintenance see our step by step article Water Heater Maintenance Tips to 2X Your Tanks Lifespan.
The temperature and pressure relief valve should be checked a minimum of twice a year. However, most people never do this. Without routine checks, the T&P valve can clog with sediment preventing it to open when needed.
The valve is normally located on the top or top side of the water heater. Make sure the T&P valve is not capped off or impeded in away way. The temperature and pressure relief valve should have a discharge pipe that terminates approximately 6 inches above the drain pan or to the exterior of the house.
If the T&P valve does not have a discharge pipe you should call a plumber to have one installed. The discharge pipe protects you and your family from scalding hot water exiting the T&P valve unexpectedly. Without a discharge pipe to direct the flow of scalding hot water severe burning can occur as water sprays fro the valve uncontrollably.
Before testing the T&P valve be sure you are wearing gloves and a long sleeve shirt to protect your hands and arms from scalding hot water.
To check the T&P valve, place a bucket under the discharge pipe (if discharges above the drain pan). Lift the lever to open the T&P valve for approximately 5 to 10 seconds. You should hear water exiting through the discharge pipe into the bucket or to the exterior.
The sacrificial anode rod attracts corrosive particles located inside the water heater and acts as a shield of defense to protect the internal tank. The anode rod protects the internal tank from rust which could weaken the water heater which could cause it to explode.
The anode rod is located inside the water heater should be replaced about once every three years. There are three types of anode rods available.
Aluminum – Aluminum anode rods are best suited for hard water. The aluminum anode rod can withstand harder water better than other types. Aluminum may be a health problem and is not recommended for drinking.
Magnesium – Magnesium anode rods are the most common type of anode rod. They are more suited for areas where water is softer. Magnesium anode rods don't last very particularly where hard water is present. Most water heaters come equipped with magnesium anode rods.
Zinc – Zinc anode rods are really zinc-aluminum alloy anode rods. The ratio of zinc to aluminum is very low, about 1:10. Zinc is added is to prevent sulfur smells in the hot water supply. If you have a sulfur/rotten egg smell in your hot water supply, you can switch out the aluminum anode rod for a zinc anode rod to minimalize the smell.
Replacing the anode rod is a relatively easy procedure however if you are unfamiliar with water heaters or working with water heaters it is recommended you call a licensed plumber to do this.
Electric water heater thermostats are located behind cover panels on the front of the water heater. These thermostats are typically factory set at 125°.
The same holds true for gas water heaters except the thermostat is located on the control module located on the front of the water heater. Once the pilot is lit, the control knob is turned to the ON setting and the desired temperature.
Some people adjust the settings as high as 140° or higher. Keeping the thermostat on this high setting will reduce the lifespan of your water heater and could cause frequent discharge from the T&P valve.
It is recommended that you decrease the temperature to 110-120°. This reduces the wear and tear on the water heater and reduces the pressure inside the tank. This setting should still provide ample amounts of hot water.
Expansion tanks are required on many municipal water supply systems now, However, many water heaters existed before the change took place. An expansion tank is a small tank that is installed on open water systems that protect the system from excessive pressure.
Expansion tanks are partially filled with air, which absorbs the shock caused by water hammer and absorbs excess water pressure caused by thermal expansion.
If you do not have an expansion tank on your water heater, you should contact a plumber to see if you need one. For more information see our article Are Water Heater Expansion Tanks Required?
One of the most common problems we find is the improper installation of water heaters. It is relatively easy to go to a home store and purchase a new water heater and install it yourself.
However, most DIY installs we find are done incorrectly. It is recommended that the installation of a new water heater be done by a licensed plumber. This ensures that the installation meets current code requirements that the homeowner may not be aware of.
Gas water heaters should be installed on an 18” stand to protect the ignition source. Gas water heaters inside garages should also have a pipe bollard or approved vehicle barrier installed to prevent a car from hitting the water heater. Most electric to gas water heater conversions lack one or both of these requirements.
Many local building codes now also require expansion tanks, seismic strapping, and drain pans which were likely not part of the old water heater installation.
If you have a gas or propane water heater, you should routinely check around the water heater for gas leaks. If you detect a rotten egg odor around the water heater you should immediately shut the gas or propane off and contact a licensed plumber.
As we discussed earlier, natural gas and propane have an ethyl mercaptan additive to make the gas detectable by smell. Installing an explosive gas detector is recommended.
The Kidde AC Plug-in Carbon Monoxide and Explosive Gas Detector Alarm is a great option that is easy to install. This explosive gas detector features:
The risk of a water heater explosion is not something that should go to bed worried about nightly. Armed with some preventative maintenance and knowledge of the warning signs, you can rest easy that your home and family are safe.
Original post: https://homeinspectioninsider.com/water-heaters-explode/
Installing a gas water heater as a DIY homeowner can be risky if not done correctly. Some of the highest risk aspects associated with DIY installation of a gas water heater include:
To minimize these risks, it’s always advisable to hire a professional licensed plumber to handle the installation of a water heater. They have the expertise, tools, and knowledge to ensure that the installation is safe, code-compliant, and free from the risks associated with DIY installation. Additionally, professional installation often comes with warranties and peace of mind.
A new water heater can potentially cause smelly water and a rotten egg smell in the hot water if there is an issue with the water quality of the water source.
Here are some reasons why you may experience a rotten egg smell in your hot water, especially after the installation of a new water heater:
It’s important to note that these issues can also happen in older water heaters as well, and not only in new ones. To address this problem, you should have a licensed professional inspect the installation, complete a water quality test, check for the presence of sulfur bacteria or high levels of sulfates, and test the water source. They will also check the anode rod and the plumbing. Based on their findings, they will recommend the necessary steps to eliminate the smell and prevent it from reoccurring.
NOTE: Water quality is a fluid and dynamic state that changes continually. As water quality changes, the needed solutions must also change and adapt if perfect water quality is desired.
When well water is present and/or iron-eating bacteria is present, an aluminum anode rod is typically considered to be a better option than a magnesium anode rod.
Here’s why an aluminum anode rod is considered to be a better option for homes with well water:
It’s important to note that even though aluminum anode rods are more resistant to corrosion in well water and water with iron-eating bacteria, it’s still important to regularly check and replace them to ensure that the water heater tank is protected. Additionally, you should consult with a plumber or water treatment professional to determine the best course of action for your specific well water or iron-eating bacteria situation.
Magnesium and aluminum anode rods are both used in water heaters as a means of protecting the tank from corrosion. However, they have some important differences as explained here.
Here are some important differences to consider regarding magnesium and aluminum anode rods in your water heater:
In summary, the main difference between magnesium and aluminum anode rods is that magnesium anode rods are more efficient in soft water and have a shorter lifespan, while aluminum anode rods are more efficient in hard water and have a longer lifespan. The choice of which one to use depends on the water hardness of the area and the budget.
When you have well water, your water heater and other water appliances require extra care to ensure that they function properly and last as long as possible.
Here are a few key things for owners of homes with well water to keep in mind:
By following these best practices, you can help to ensure that your water heater and other appliances are in good working order and that they last as long as possible. More importantly, you can ensure your family has safe healthy water for all your needs.
Hot water from the home's faucets and sinks can cause serious injury to members of the family. Underestimating the risks posed by burns and scalding wounds only makes members of the household more vulnerable to injury. The following facts about scalds and burns can help illustrate the dangers of improperly heated water in the home.
1. Kids and seniors face the highest risk
Seniors and kids under the age of 5 are especially vulnerable to serious scald injury. A thinner dermis poses an extra threat of deeper burns in children, while limited flexibility can sometimes put seniors in danger with regards to nearby hot water.
2. Overheated water is a common problem at home
Ironically, many homeowners that balk at the idea of burn-related injuries in the home are at the greatest risk. Over 40 percent of inspected urban homes were found to have water heaters set at or above 140 degrees. Setting water temperatures to 120 degrees will increase safety and heating efficiency simultaneously.
3. Serious burns can occur in seconds
Burn wounds caused by a home's water supply can occur quickly. In fact, 140 degree water can cause a third-degree burn after just five seconds of exposure.
4. Cool water is better than ice for temporary treatment
Resist your instinct to ice a serious burn or scald, as treating the injury with ice actually risks worsening the burn. A wet compress or a flow of cool water will do the trick until you can schedule a medical visit.
5. Scalding injuries are mostly preventable
While hundreds of thousands of scald wounds occur each year, 75 percent of burn injuries in children are preventable. Families taking a proactive approach toward preventing burn injuries will see rapid results in the form of fewer burn accidents.
6. Going tankless can eliminate scald injuries
Often performing maintenance on an aging water heater simply increases risks of a scalding accident. Electric tankless water heaters have more precise, reliable heat controls to help prevent burn injuries.
SOURCE: https://webflow.com/design/hot-water-safety
They get too hot, the water inside turns to steam. Steam takes up far more room than the water it once was, and the expansion rips the water heater apart. And make no mistake, there have been some spectacular water heater explosions. The MythBusters have addressed (if that’s the right word) this issue several times:
If this happens in your home you probably won’t show the same level of enthusiasm as these fellows, though. Here’s another less, ah, flamboyant link:
Water Heater Explosions – Should You Be Concerned? | Water Heater Hub
Naturally, there are safety devices to prevent this, mainly a thermostat to turn off the heat source (gas or electric) before things get anywhere near too hot. The next safety device is the T&P valve, the temperature and pressure valve, designed to open if the temperature or pressure gets too high. In order to make the video above, the MythBuster guys had to disable the thermostat and remove the T&P valve.
Of course, no homeowner would ever do that, but over time the T&P valve can get stuck, then fail when it is needed. It needs to be tested, maybe about once per year; if it keeps leaking after the test, have it replaced. There’s no end of websites discussing water heaters and required maintenance, just search “water heater t&p valve.” Here’s one chosen at random (NOT an endorsement!):
Water Heater Temperature & Pressure Relief Valve Discharge Pipe
Original reporting: https://www.quora.com/What-happens-when-a-hot-water-heater-explodes-why
Nine recently confirmed cases of Legionnaires’ disease in Hopkins, MN reminded me of an old blog post that I thought would make for a timely re-blog, along with some updated information. First, here’s the story about the recent cases in Hopkins: http://www.startribune.com/mdh-hopkins-warehouse-and-fountain-under-investigation-as-possible-source-of-legionnaires/393567731/. As mentioned in the story, Legionnaires’ disease resembles a severe case of pneumonia and is spread by inhaling the fine spray from water sources containing Legionella bacteria. In your home, the source of that bacteria could be your water heater, especially if you turn your water heater temperature down to the “vacation” setting when leaving for extended periods of time. The people who are most at risk for Legionnaires’ disease are those over 50, smokers, or those with certain medical conditions.
According to LegionellaPrevention.org, legionella bacteria can grow at temperatures from 68° F to 122° F, but the ideal growth range is between 95° F and 115° F. When it comes to preventing legionella bacteria growth, hot water is better. Legionella bacteria cannot multiply at temperatures above 122° F, and are killed within 32 minutes at 140° F. So crank up the water heater as high as it will go, right? No, of course not. That would create a scald hazard. Water heater manufacturers put a warning on water heaters saying the water temperature should not exceed 125° F to help prevent “severe burns instantly or death from scalds”. Their words, not mine.
So what’s the perfect temperature for your water heater?
Unfortunately, there’s no simple answer. The American Society of Sanitary Engineering Scald Awareness Task Group released a white paper many years ago on this topic, which essentially says that there is no perfect temperature to set your water heater to. Part of the reason is that traditional tank-style water heaters don’t keep the water in the tank at an exact temperature; there is a temperature “band” that tank water heaters maintain. At the beginning of a heating cycle, a water heater set to 120°-ish might start at 115° F, and might get up to 125° F at the end of its heating cycle. There’s more to it than just that, but the point is that water heaters do not produce constant temperatures.
If the water in a tank is kept below scalding temperatures, there is a potential for Legionella bacteria growth. Ideally, the temperature in a water heater tank should be cranked way up to 140° F or higher, but now we’re back to the scald hazard thing. One solution is to have a hot water tempering valve installed for the entire home.
This valve would be installed right at the hot water outlet of the water heater. It would allow the water heater to be cranked up to a scalding 140° F, which would be sufficient to kill bacteria and would extend the capacity of the hot water tank, while at the same time reducing the temperature of all of the hot water throughout the house. Click the following link for more information about these devices: http://media.wattswater.com/F-MXV.pdf . While these devices won’t guarantee safe water temperatures at every fixture, they’ll get you a lot closer.
If you want more hot water out of your water heater and you want to reduce the risk of Legionella bacteria growth, hire a plumber to install one of these mixing valves at your water heater and turn the temperature up on your water heater. I should also mention that point-of-use thermostatic mixing valves should ideally be installed at the faucets for the highest level of safety… but I’m pretty sure I’ve never seen a home fully outfitted with those.
