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All You Need to Know About Storage Tank Water Heaters & 2017 Reviews

Among the many systems that exist to supply a home with hot water, storage tank heaters are perhaps the most common. However, not all conventional storage water heaters are created equal. Whether you’re looking to replace your old heater or want to install one for the first time, there are many considerations to make. For instance, you need to decide what type of storage water heater to install, the ideal capacity, type of fuel to use, and basic installation requirements. We shall discuss all of these aspects in this complete guide about tank-style water heaters. First, let’s have a look at how these appliances work.

Top 3 Storage Tank Water Heaters

Here are unit reviews for three high-rated storage water heaters that you may want to look into.


#1 – AO Smith PXNS-50 Residential Electric Water Heater Review

The AO Smith PXNS-50 residential electric water heater is ideal for families that need to store 50-gallons of hot water. It can be used in homes with 2-3 baths or for running more than one hot water appliance at the same time. The heater has a first hour ranting of 62 gallons and comes with many energy conservation features.


Key Features

Storage water heaters are known for being the most inefficient at preventing wasted energy. However, this model from AO Smith has a number of features designed to minimize standby heat losses and reduce energy consumption. To begin with, the tank features 3-inch CFC-free foam insulation and external heat traps. In addition, this heater has two 4,500W incoly steel heating elements. These low wattage, Phoenix steel elements are designed to operate efficiently and last up to 3 times longer than ordinary copper resistant heating elements.

Other innovative features to expect from the AO Smith PXNS-50 electric water heater include:

  • Blue Diamond Glass Coating

Like all storage water heaters, the tank on this model is lined with glass to minimize corrosion. However, the AO Smith PXNS-50 water heater has a Blue Diamond glass coating, which offers over twice corrosion resistance compared to industry standard glass lining.

  • Double Magnesium Anode Rod

For added corrosion resistance, AO Smith equipped the PXNS-50 electric water heater with two magnesium anode rods, one in a standard separate port and the other rod in the hot water outlet port.

  • Dynaclean II Sediment Cleaning System

Perhaps the most innovative feature on this water heater is the DynaClean II automatic cleaning system. This function is basically a specially designed dip tube that delivers cold water to create turbulence in the tank. Turbulence created prevents sediment and lime from accumulating inside the tank. As a result, this function helps to prolong tank life while at the same time maintaining high-energy efficiency.



  • 10-year limited manufacturer warranty on parts and tank
  • Features such as Blue Diamond glass lining and double magnesium anode rode provide added protection against corrosion
  • Designed with an Energy Factor of 0.95
  • UL 174 Certified for home use
  • Equipped with brass temperature resistant drain cock as well as a temperature and pressure relief valve


  • Although AO Smith offers a 10-year warranty on this water heater, they won’t honor it if you purchase your unit from an unauthorized distributor
  • Bulky design



The AO Smith PXNS-50 electric water heater weighs about 194 pounds with a tank that stands slightly over 4 feet tall. Therefore, you will need more than one person to move this unit inside the house when it arrives. This appliance also uses 240V of electricity, so make sure that your home’s power supply meets this requirement before purchasing it.

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#2 – Reliance 6 6 SOMS K 6 Gallon Compact Electric Water Heater Review

Are you looking for a low capacity and easy to install water-heating system? If so, the Reliance SOMS K 6 Gallon compact electric water heater might be just what you need. This water heater is the perfect size for anyone that lives alone. However, it’s mostly aimed at users looking for a water heater for mobile homes, trailers, and RVs or inline booster for point-of-use tankless water heaters.


Main Features 

For this water heater to operate properly, you need to ensure that your home’s power supply can meet the appliance’s electrical requirements. This is a 240V/1650Watt water heater. It uses about 13.75 amps, so you can connect it to a 15amp circuit breaker with a 14-gauge wire. Alternatively, a 20 amp circuit with 12-gauge wire will work. When it comes to features and functionality, here is what to expect from this conventional water heater.

  • Fast Recovery Time

The 6-Gallon reservoir can reheat water in as little as 30 minutes. It only uses a single 1650-Watt copper heating element. Compared to larger models, this Reliance electric water heater has a low power draw, which means you don’t have to worry about high electricity bills.

  • Space Saving and Affordable

The price for this unit is quite reasonable considering that the tank is rather small. The tank is about 15.25 inches tall and a little over 14 inches in diameter. Due to the small size, this storage water heater is ideal for space-limited situations. It can easily go under the sink, crawl spaces or a kitchen closet that is wide enough to accommodate the tank.

  • Comes With Factory Installed Controls

You won’t have to tweak or customize the Reliance 6 6 SOMS K electric water heater when it arrives. All controls and fittings are already factory installed. This includes a drain valve at the base of the tank (threaded to take a hose), side mounted inlet and outlet water fittings, the temperature and pressure relief valve as well as an external thermostat and heat adjustment switch.


  • Comes with 6 year warranty for parts and tank as well as 1-year warranty on labor
  • Inexpensive option for those who don’t want to install a full tank unit
  • Lightweight and easy to install


  • Not suitable to use as a whole family water heating system due to the small tank capacity


Reliance requires buyers to register water heaters on their website in order to keep the warranty in full effect. It’s also important to ensure that you buy your unit from a recognized dealer and have it installed by a licensed electrician to avoid warranty issues.

Overall, this unit is a great option for situations where buying a full tank system would be overkill and you only want a small yet reliable source of hot water.

#3 – BOSCH Tronic 3000 T Electric Mini-Tank Water Heater Review

The new Bosch Tronic 3000T line of electric mini-tank water heaters is an upgrade from the previous Ariston Pro Ti series. The rebranded mini-tank heaters and older models are still the same size. However, replacement parts differ slightly but are still compatible on all models.

bosch tronic

Just like in the Ariston Pro Ti line, the Bosch Tronic 3000T mini-tank electric heaters now come in three sizes. These include the 2.7, 4, and 7-gallon units, each named as the ES2.5, ES4, and ES8 respectively.

The Bosch Tronic 3000T series now features new improvements. For instance, the temperature adjustment knob is no longer mounted under a grey oval cover. Instead, this control has been installed on the front for easy access. The Bosch Tronic 3000T mini-tank electric water heaters also have an improved thermostat that features a new sensing probe for quicker temperature adjustments and consistent heating.


Top Features of the Bosch Tronic 3000T Electric Mini-Tank Water Heaters

The Bosch Tronic 3000T electric mini-tank heaters require a 120-volt outlet and they draw at least 12 amps. The 2.5 and 4-Gallon units can simply be plugged into a wall socket, but the larger 7-Gallon model must be hardwired to the power outlet. According to the manufacturer, these units require a water pressure range of up to 150 PSI. On the ES 2.5 and ES4, you will need 1/2-inch male NPT water fittings. The larger 7-gallon ES8 model uses 3/4-inch male NPT water fittings.

All units have a recovery rate of 6.8-gallons per hour when the required temperature rise is 90 degrees F. However, the first hour rating can be higher if the temperature of incoming water is high. Equipped with a 1440-Watt heating element, these electric mini-tank heaters reduce the wait time for hot water when installed at the point of use. Below is a list of other features to expect from the Bosch Tronic 3000T line of electric mini-tank hot water heaters.


  • Compact and Elegant Designs

With their sleek and attractive designs, these water heating units will add to the existing décor of your home. As an added bonus, their small sizes allow for installation in unconventional spaces. For instance, the 2.5 and 4 gallon units can easily fit under the skin or inside a cabinet. These units also come with brackets if you want to mount them on the floor, shelf or wall.

  • Insulated, Glass Lined Tanks

The mini-tanks for these water heaters feature a thick CFC- free foam insulation to minimize standby heat loses. For added durability, the tanks are lined with glass on the inside.



  • Lightweight, compact, elegant and space saving designs
  • Units can be installed independently or in-line with main central hot water source to reduce wait times
  • Glass lined and insulated tanks for long life and better energy efficiency
  • Available in multiple tank sizes
  • 98% energy efficient
  • Temperature and pressure relief valve included


  • The mini-tanks have a small capacity, so don’t expect to take long hot showers

bosch tronic-3

The Bosch Tronic 3000T line of mini-tank electric water heaters offers a good balance between pricing and size. If your home has hot water fixtures located far from main heating source, then these heaters would provide a great boost.

How Storage Tank Water Heaters Work

Traditional tank water heaters all work in a similar fashion. The main difference between them lies in the type of fuel used to heat water.


Energy sources commonly used to power conventional tank-style water heaters are electricity and gas (natural or propane). There are some oil-fired models as well, although not as common as the first two types. In most designs, cold water enters from the top through a dip tube that funnels it to the bottom of the tank where heating elements are situated.

Electric and gas-fired hot water storage tank heating systems both have a thermostat that senses water temperature. In an electric water heater, the thermostat is usually mounted flush against the side of the tank. When the temperature drops, the switch closes, allowing current to flow. Electric units may have two heating elements, one mounted at the bottom and another found in the middle of the tank. The heating elements remain submerged in water and pass electricity through a resistant material that converts electrical energy into heat. Once water heats up to the preset temperature, the thermostat opens to break the circuit.

The thermostat in a gas-fired storage-tank water heater typically uses a small copper tube with a mercury sensor at the tip. This component works in conjunction with the gas control valve and thermocouple to regulate the water heating cycle. When water in the tank drops below the preset temperature setting, this triggers the thermostat to activate the gas control valve. Before the gas control valve opens, it first sends a signal to the thermocouple to ensure that the pilot light or spark ignition is on. If so, the valve opens, allowing gas to reach the burner and ignite a flame. When the water temperature reaches the preset setting, the thermostat sends a signal to the gas control valve to cut off gas flow, thus extinguishing the flame.

The burner in oil-fired storage tank heaters is similar to that found in an oil-fired furnace. In either case, the burner is usually mounted under the tank to heat water from below.

Since tanked systems heat water from the bottom, warm water rises naturally through convection and flows through the outlet pipe at the top. When a hot water fixture is opened, cold water enters from below again though the dip tube to restart the heating cycle. The water is constantly heated to maintain the preset temperature, which typically ranges between 120 and 140 degreesF.

Gas and oil fired water heaters have flue systems to remove combustion emissions from the home. On all tank-style water heaters, you will also find a Temperature and Pressure (T&P) control valve. This valve opens if water temperature or pressure exceeds a safe limit. It’s usually connected to a pipe that leaves about 6-inches clearance from the floor. It’s therefore advisable to leave a bucket under the pipe so that any spillage will be captured when the T&P valve opens.

At the base of every tank, there’s usually a drain cock. This valve empties the heater or flushes out sediment. Hot water storage heaters are also equipped with a valve on the inlet pipe, which shuts down the hot water plumbing without interfering with the homes cold water supply.

Most models have steel tanks lined with glass on the inside to prevent corrosion caused by minerals found in hard water. Corrosion is the main reason why many water heater tanks fail. However, some manufacturers add an outer layer made of magnesium or aluminum anode rod, which rusts in lieu of the tank. Eventually, the rod wears out and corrosion of the tank accelerates. There are temporary fixes for holes produced by rust, but once a tank begins to wear off, it should be replaced.

Storage tank water heaters can last anywhere between 10-15 years. However, gas and fuel-fired models have shorter expectancies because direct heat from burner flames cause accelerated wear and tear on the storage tank.


Exploring Storage Tank Water Heaters by Fuel Type

If you’re thinking about buying a tanked water heating system, you may be wondering what fuel source to settle for. The fuel your tanked unit uses will have an impact on both the annual cost of heating water and the heaters efficiency.

Some water heaters conserve more energy than others do. For instance, electric water heaters have Energy Factor ratings of 0.75 to 0.95 whereas their gas-fired counterparts are rated between 0.5 and 0.7.

Although storage tank electric water heaters use their fuel more efficiently, that does not make them more economical. In most countries around the world, electricity tends to cost more than gas. This may lower the operating cost of running gas-fired water heaters, but keep in mind that these models typically cost more to set up because of the added expense of installing venting and gas line fixtures.

Within the category of gas-powered water heaters, you also have to decide whether to go for versions that use propane or natural gas. In most cases, the choice is usually dictated by which fuel source is more readily available in a given area. If availability is not an issue, then it boils down to cost. Propane has a higher thermal heat output than natural gas, but it tends to be more expensive.

It’s also worth pointing out that tanked water heaters can also use solar energy as a fuel source. The basic setup of a solar water heater comprises of a collector (solar panel) and storage tank. The collector is simply a glazed, insulated panel with a dark-interior that houses a bunch of water passage tubes. As water passes through the tubes, the solar panel turns the sun’s rays into radiant heat. The storage tank is exactly what it sounds like, a reservoir for hot water.

Since solar water heaters rely on renewable energy in the form of sunlight, they offer the largest energy savings. However, these systems are not ideal as standalone weather heaters since they are affected by weather changes and some models rely on electricity to pump hot water. For this reason, solar water heaters are typically used alongside conventional storage tank units.


Storage Tank Heater Household Sizing and Water Usage

Storage tank heaters are the best choice for homes that have multiple hot water fixtures. The fact that these heaters hold hot water in tanks makes them ideal as whole house water heating systems. You can find models equipped with water tanks that hold anywhere between 20 and 120 gallons, with 40 to 80 gallon units being the most common.

Tank capacity and fuel type can give you an idea of what water heater size to choose. Typically, gas heats up water faster than electricity. The simplest way to measure hot water needs is by considering the number of bathrooms in a home and the type of fuel the heater will use. For example, the minimum recommended size unit for a four-bath house with an extra-large bathtub is 75-gallons for a gas-fired heater, and 120-gallons when using an electric unit. If your home has two to three-and-a-half baths, get a 50-gallon gas fired heater or an electric unit that stores 66-80-gallons of hot water. For a one-bathroom house, 30 to 40-gallon tanked heaters should suffice.

Keep in mind that some factors can skew these standards. For instance, situations that naturally call for a large-capacity storage water heater include a laundry heavy family with small kids, many occupants living in a small house, or a home with an especially large bathtub. It is important to match size to your family needs. If you’re in doubt, ensure to seek guidance from your preferred storage tank water heater manufacturer.

Another important factor to look into when sizing a storage-tank water heater is the unit’s first hour rating (FHR). The FHR is an indication of how much hot water the heater can deliver every hour at peak usage. Ideally, you want to make sure that the first-hour-rating of your chosen water heater can supply enough hot water to serve all bathrooms and residents in the house.

Federal efficiency standards that took effect on April 16, 2015 now require all new conventional storage water heaters to have an EnergyGuide label. Check this label on any unit you wish to purchase since the first-hour-rating is usually indicated there.



General Pros and Cons of Storage Tank Water Heaters

Before having a conventional water heater installed in your home, first make sure to learn about the inherent drawbacks and benefits that this kind of system has. The following list of pros and cons associated with storage water heaters can help you make an educated decision.

  • Lower Initial Setup Cost

One of the reasons why many people find storage water heaters appealing is because these systems are inexpensive. In fact, their installation can be half as much as a tankless water heater.

  • Easy and Inexpensive to Replace

Should your tanked heater go bad, it can be replaced easily with a similar unit without incurring large installation expenses.


  • Higher Utility Bills

Conventional heaters heat and reheat water to maintain a preset temperature. Since these units remain on all the time, a lot of standby heat goes to waste. This translates to higher energy bills on the user’s part. Newer systems manufactured from 2015 are now Energy Star certified, which makes them more energy efficient than older models.

  • Tanks Take Up Space

Most traditional water heaters are big and bulk since water needs to be stored in a tank. These units take up a large amount of space in either the basement, laundry room, or kitchen closet.

  • Runs Out of Hot Water

If a storage water heater is not properly sized or during times of high demand, it will run out of hot water, making you wait up to 30 minutes or more for it to heat up water inside the tank again.

  • Restricted Installation

Unlike tankless systems, storage water heaters can only be installed indoors.

  • Less Durable

A good storage tank heater will have a life expectancy of 12-15 years, but tankless models tend to last almost twice as long.


Basic Installation Requirements for Storage Tank Water Heaters

Installing a storage water heater is quite simple especially if the new unit is similar to an old one. Whether you’re replacing your unit, switching from electric to gas or simply installing a new system for the first time, there are many installation requirements that you must comply with in order to install a storage water heater. The following are some of the common codes and safety issues to observe when installing a conventional water heater.

  1. General Codes and Safety Regulations
  • Water Pressure Regulators

When operating a tank-style heater, the water pressure should be kept at 80 PSI or below. The reason for this is that high water pressure can damage plumbing fixtures and even cause premature cracks on the glass lining of the water heater’s tank. Installing pressure-regulating valves will prevent unnecessary stress on your plumbing and hot water heating system.

  • Expansion Tanks

When water is heated, it expands and increases pressure within the plumbing system. Since increased pressure can shorten the lifespan of a storage water heater, sometimes is its necessary to install an expansion tank. The expansion tank provides relief for excess water pressure and protects your home’s plumbing system. Whether or not an expansion tank is needed depends on the water supply’s pressure, which can be determined by running a PSI test.

  • Dedicated Water Shut-Off

As the name implies, a dedicated water shut-off valve will turn off water supply to your heater but not the entire home. This will come in handy when servicing the water heater because you won’t be inconvenienced with having to cut off water supply to the rest of the house.

  • Pans and Drains

Storage heaters may develop leaks, which in turn can cause a lot of water damage in your basement or at the installation site. Therefore, it’s a general requirement to install a drip pan with a drain line beneath your hot water heater tank.

  • Pressure And Temperature (P&T) Valve

Storage tank water heaters usually have a pressure and temperature relief valve, which opens when water pressure exceeds 150 PSI or temperature reaches 210 degrees F. Water comes out at very high pressures and can be extremely hot when this valve opens. To avoid accidents, some areas require the P&T valve to be piped to the exterior.

  • Earthquake Straps

If your home is in an earthquake zone, you’ll need to secure the water heater with straps to ensure your safety in case of a disaster.


  1. Electric Storage Water Heater Codes
  • Insulated Bottom Board

When installing electric water heaters in unheated spaces, it’s a general requirement to place the tank on an insulated, incompressible surface with a minimum resistance of R-10. The bottom board increases energy efficiency by preventing heat losses from beneath the tank.


  1. Gas-Fired Water Heater Codes
  • Venting Requirements

Besides being fed by a gas supply line, water heaters that use propane or natural gas require a flue connection to carry away harmful combustion gases such as Carbon Monoxide.

  • Installation Site Requirements

The installation site for a gas-fired storage water heater must be carefully chosen. For example, some manufactures will not install gas units close to fans, ventilation systems, or clothing dryers. The reason for this is that air-moving devices can affect the proper operation of a gas-fired storage water heater or even extinguish the flame.

  • Sediment Trap

It’s a requirement to place a sediment trap on the gas line that feeds fuel to a storage water heater as close as possible to the inlet. This installation code prevents debris and moisture from entering the hot water heater’s firing chamber.

Keep in mind that there are many other installation requirements and codes for setting up a storage water heater besides those listed above. Make sure to check your local building department for exact specifications. To ensure your own safety and prevent voiding the warranty, always hire a licensed professional to install a water heater for you.

If you’re in the market for a storage water heater, it’s wise to compare your options. There are many brands in the water heater industry these days. This means that you can get models that offer better value than the rest. Weeding through the numerous brands that exist can be confusing because most, if not all, water heater manufacturers claim to be the best. There are also many considerations to make when choosing a storage water heater. For instance, aspects such as installation costs, tank capacity, and energy efficiency must be taken into account.


Other awesome guides:

Best Tankless Water Heaters Guide
Best Hybrid Water Heaters (Heat Pump) Guide & Reviews
Best Whole House Water Filter 2017 – Guide & Reviews
Best Reverse Osmosis System Guide

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