How to Choose a Water Heater, According to Science

There are many who want to buy an efficient and stable water heater for their homes. But do they? Water heaters do the difficult job of heating the water supply of your home. Providing you with immediate hot water when needed through various fixtures and knobs.

Like many other appliances, a water heater is more convenient than manually heating up the water whenever needed. It cuts back time and effort, for most homeowners, while making life simpler. So why do most people hurry when choosing the right water heater? Something this important needs careful consideration of features and functions.

heating 706945 640

The best part about using the best water heater is that it lasts for years. It requires minimal maintenance and even if you hire a professional to maintain one, it doesn’t cost you big bucks. That said, finding a dependable water heater isn’t easy.

Because water is being constantly heated inside the tank, it needs to be energy efficient and spacious enough to accommodate the entire house. Anything that takes up more energy is a waste, costing you a hefty power bill.

So how do water heaters work?

A residential water heater stores up to 80 gallons of water that is sufficient for the whole house. More unconventional water heaters come with higher capacity ranging from 20 gallons up to hundreds. Powered by different sources, such as fuel oil, natural gas, propane oil, or electricity, a water heater uses a rugged gas burner to heat up the cold water entering the tank.

You can set your ideal temperature point for the gas valve to maintain a solid hot water flow. This can also be done with the help of a thermostat. As soon as the water’s temperature drops, the gas valve opens to heat the water to the right temp. When using an electric water heater, instead of the gas valve there are two or more electric coils that heat the water.

The upper half of the tank maintains a higher thermostat setting than the lower half. This is because the upper half is closer to supplying hot water on demand. To keep the water constantly heated, some modern water heaters have insulated tanks to prevent heat loss.   

The second most important part of a water heater is to maintain hot water until it’s ready to use. So to reduce stand-by heat loss, opting for heavily insulated and thermal tanks is ideal. (1)

1. Choosing The Right Type

It’s wise to consider all types of water heaters before making a final decision. You can even consult a professional after reading this guide to get more information about your ideal type of water heater.

Note: All water heaters are designed with energy-efficient features, so picking the right type is a matter of personal convenience and choice.

Tank water heater: A storage tank is the most traditional type of water heater. It features a durable insulated tank where cold water is heated using a heated element and is stored until ready to use. Generally, single family homes make use of tank water heaters for years.

They provide up to 80 gallons of heated water with enough water supply so you never run out of hot water to use. It consists of many components including delivery pipes and valve settings on the top of the tank. A supply pipe on the bottom that keeps filling the empty space with cold water to heat.

For durability, tank water heaters are made of tough steel. While some come with heavily insulated materials for heat retention. If you ask me, it’s a good idea to buy an insulated water tank to prevent stand-by heat loss. So you get hot water without waiting for a few minutes.

Tankless water heater: Using a tankless water heater has its pros and cons. In terms of advantages, they’re more energy efficient and take up less space than tank water heaters. For people who don’t use hot water a lot or want hot water for showering can buy a tankless water heater.

It proves up to 4 gallons of water at a time. This is because the water is heated through the water heater and not stored. The heating coils inside the tankless water heater heat the cold water only when you switch it on. There are multiple types of tankless water heaters including electric and natural gas heaters.

Hybrid water heater: Hybrid water heaters work by absorbing heat from the outside air. They’re more energy-efficient than both tank and tankless water heaters. And their installation and maintenance is to the minimum cost.

The drawback to using hybrid water heaters is that you won’t be able to place them in colder temperatures. A hybrid water heater requires at least 40 to 90-degree temperature for optimal water heating. Plus, it needs to be kept away from other appliances to capture a lot of heat.

Solar water heater: Like the name suggests, a solar water heater works by absorbing the sun’s rays to heat water. It’s probably the most efficient way of heating water, saving money and power. You can only use a solar water heater on sunny days, whereas they’re kept vacant during winter months. (2)

Most people consider a solar water heater as a backup system.

2. Does It Have A Warranty?

Buying a reliable water heater includes a solid warranty. According to Consumer Reports, water heaters offer up to 12 years of warranty. But if you decide to pay more, buying a unit for a longer warranty is also possible. (3)

Models with longer warranties come with tougher components including the heating element, thicker insulation, etc. This also helps speed up the water heating process for bigger homes.

Always check for the following warranty information when choosing a water heater. This will help you differentiate between the good and bad without making a mistake.

  1. Most models cover all water heater parts including the tank, temperature valves, flow pipes, and heating elements.
  2. Some warranties cover installation costs to ensure proper wiring, ventilation, and sizing of the unit.
  3. Advanced models offer durability warranty which covers corrosion, leaks, and anode damage of the water heater.
  4. Some water heater brands offer features that reduce heat loss and stand-by heat loss in storage tank models. This also reduces mineral buildup on the bottom of the water tank, causing contamination and bacteria.

You will find plenty of specifications on water heaters based on their type and size. So choosing a professional water heater with the longest warranty is important.

3. Considering Capacity

You can also buy a water heater based on its gallon capacity. Most people prefer buying one on the basis of capacity rather than type, especially in bigger residential apartments and homes. A family of four, for example, require a bigger gallon water heater for showing, dishwashing, and laundry needs.

You don’t need to buy a water heater of a whopping gallon capacity, but it’s always good to install the average for a big family. If you enumerate total hot water use based on a person’s showering, dishwashing, and laundry needs, it should total to a 100 gallons for a family of four, for instance. But this doesn’t mean you should hunt down a water heater with that much capacity.

You can need to find something that delivers a sufficient amount of hot water, either per hour or per minute. Based on the type of water heater you buy, that is tank or tankless, can you determine the first-hour rating and a gallons-per-minute rating of a unit.

These factors tell you how much water a water heater can deliver, so you don’t have to wait for it to fill up each time the tank empties out. This creates a continuous water cycle for both tank and tankless water heaters. Hence, determining the best water heater unit for you.

If you’re buying a tankless water heater, it’s important to know that getting continuous hot water from different fixtures such as the shower and the dishwasher is not possible. You might need two separate tankless units for each purpose for consistent hot water flow.

According to a report, a basic shower takes around 17 to 18 gallons of water, that is if the shower lasts for at least 8 minutes. To sum it up, you exhaust 2 gallons of water per minute while showering. (2)

Using a dishwasher, on the other hand, is more water-efficient than hand washing. An energy-efficient dishwasher can use 3 gallons of water per load. While washing dishes by hand uses up to 30 gallons in the sink. (4)

Lastly, a collective study proves that a single person uses about 80 to 100 gallons of water every day. This includes showering, teeth brushing, dishwashing, face washing, hand washing, flushing, and cooking water. (5)

Based on these numbers, it is safe to say that buying a higher gallon capacity water heater for an entire family with a suitable FHR (for storage units) or GPM (for tankless units) will get you to the capacity you actually need.

4. Comparing Costs

Buying and installing a water heater amounts to a huge sum for a residential space. It’s wise to know how much you will be spending for a model that will last for years.

This will give you an idea of how much a standard water heater costs and how much should you expect to invest in its installation and maintenance. But this margin differs from type to type, so comparing the costs is critical.

Electric water heaters: Electric water heaters are generally more expensive than gas or tankless water heaters. But it’s less expensive than gas water heaters. So their installation and maintenance cost is much lower than any other. For a whole house, a sufficient electric water heater might cost you up to $700.

The installation of an electric water heater is less cumbersome as it doesn’t require gas refilling, piping, etc. For tankless water heaters, which are mostly electrically powered, the installation is more expensive than the maintenance.

Gas water heaters: Gas water heaters, for an entire house, cost up to $1000 to $2000. Installation digs a deeper hole, making installation as costly as maintenance for gas-powered models. Modern water heater models come with gas conversion costs as well. This holds true for most energy efficient models on the market.

According to a report, tankless water heaters incur greater installation costs. Especially when it involves new-home installation or home-remodeling installation. (6)

5. Checking The Fuel Type

Considering the fuel type of a water heater before buying might save you from investing in the wrong one. While most traditional water heaters use electricity for water heating, there are other ways to get a constant supply of hot water.

Knowing this will help you narrow down your search for better water heater options. If you want to upgrade to something better, it’s time to replace old water heating systems that rust your basement. There are several things to look up to such as the type of fuel, cost of fuel, and efficiency of the fuel when considering a new water heater.

Choosing the type of heating fuel: You can choose from natural gas, propane, fuel oil, or geothermal energy. Other two distinctive options are electricity and solar power.

Cost of the heating fuel: The next thing you’d want to consider is the amount you will be paying for the cost per unit. For natural gas, fuel oil, and types that are liquid, you are charged by the gallon. On the other hand, hard materials such as wood, are charged by cubic foot.

Heating fuel efficiency: Is the new heating fuel more efficient and reliable? According to a report, checking the Annual Fuel Utilization Efficiency of a fuel type can help determine how much heat is generated and consumed for hot water.

It also suggests that any type of fuel, whether wood, natural gas, or fuel oil, doesn’t convert 100% of its energy to warm the water. Because of many factors such as cooling down, heat retention, etc. some of the fuel’s energy is lost.

If the AFUE of a fuel type is labeled above 85% or higher is worth considering for energy efficiency. (7)

Based on the fuel types available for water heater, it’s important to know the basics of each before choosing.

Electricity: A good alternative to fuel, electric water heaters can be used for tank and tankless units across the globe. In fact, they’re the most commonly used and traditional water heaters on the market.

Fuel oil: Some water heater models come with dual fuel oil and propane oil systems. The best thing about using fuel oil is that they provide a higher storage capacity and more energy efficiency than any other.

Natural gas: Natural gas water heaters are ideal for bigger families. They offer powerful operation with a long-lasting supply of hot water. It’s an eco-friendly choice for water heaters. Some say it offers excellent thermal efficiency to generate a constant flow of hot water. (8)

Solar energy: Solar water heating wasn’t a popular water heating choice some years back. But now more and more consumers are becoming environmentally-friendly by opting for solar water heating.

Professional solar water heaters come with two parts: storage tanks and solar panels. But installing a solar water heater depends on the climatic conditions, building infrastructure, and safety standards.

6. Is It Energy Efficient?

Nothing beats an energy-efficient water heater. When selecting a new unit for your home, choose a heater that will not only offer constant hot water but also offer energy-efficient back up. Ultimately, saving you money so you can use it for longer.

A water heater is measured based on an Energy Efficiency Factor, or EF. With two water heaters in front of you, if one has a higher EF measure and the other does not, the former one uses less energy to convert cold water into hot water.

Conventional water heater units come with 58 to 60% EF while more energy efficient models have 67% EF. If you top for tankless models with a higher EF as opposed to an electric model with the same EF measure, it’s good to opt for a tankless water heater.

The energy savings of a water heater also depend on the type of heater you buy, that is tank storage or tankless. But it also depends on other factors such as energy-efficient dishwashers, shower heads, and faucets.

Here’s how a water heater can be made more energy efficient. (9)

Fixing leaks: If your water heater tank leaks, it’s time to buy a new and upgraded one. But checking for any other leaks around the house can save hot water use drastically.

Using less powerful fixtures: High-powered fixtures offer a higher flow than necessary. This wastes more water, which directly affects the amount of hot water expenditure from the unit. If you opt for low-flow fixtures, the energy efficiency quotient of a water heater can increase, saving at least 25 to 50% water every year.

Buying energy-efficient appliances: Dishwashers and washing machines that use less energy also use less water to save the planet. Washing dishes in an energy-efficient dishwasher can reduce the demand for hot water when operating on full loads.

The same approach applies to washing machines that use less water to thoroughly clean dirt and odor from large clothes batches, at one time.

According to Natural Resources Canada, buying a water heater with ENERGY STAR ratings can cost water heater costs by a huge amount. (10)

This is because all ENERGY STAR rating units come with strict energy efficiency standards. So finding an energy efficient water heater is important to avoid costly power bills and maintenance costs.

Replacing Your Old Water Heater

Is it the right time to replace your water heater? Sometimes repairing a damage is much easier than replacing the whole unit off the wall. And with frequent maintenance rounds, you can ensure proper functioning on a standard water heater. (11)

The information I’ve got for you below will help you determine whether your current water heater needs replacement or not. If your water heater is still under warranty, getting some faulty parts replaced is a good alternative. Plus, it saves money!

Before you begin, you should know that an efficient water heater won’t last for more than 15 years. So you can troubleshoot the following issues with your water heater to ensure it hasn’t reached its peak.

For an electric model:

  • You can start by checking the power source of the unit. Re-adjust the thermostat setting to make sure it’s working properly.
  • Some models work better after flushing the built-up sediments from the bottom of the tank.
  • If the water pipes connected to the unit aren’t insulated, getting them checked is necessary. Proper insulation can prevent unnecessary leaks and overheating.
  • The heating elements needs to be replaced if the thermostat isn’t reaching its ideal temperature.
  • You can check the heating element’s efficacy by increasing the thermostat settings for a higher temperature.
  • A mild hissing sound from the tank might mean debris or sediment build-up.
  • Tighten the water pipe lines going toward and away from the unit.

For a gas model:

  • Any gas-powered unit must be properly connected to the gas collector with the pilot light on.
  • Gas models also work better after flushing out the built-up sediments from the tank.
  • Properly insulate the water pipes, especially the hot water pipes.
  • It’s time to clean the gas burner and replace the thermostat. In gas models, there are thermocoupler which is responsible for automatically shutting off gas flow if the pilot light is off. You need to clean the thermocoupler too.
  • You can check if the gas burner is working by raising the temperature on the thermostat.

After you carry out these steps, if the water heater is still showing troubling signs of damage, it’s to replace it. There are can a few factors to take into consideration when opting to replace a unit.

  1. The gallon capacity of your current unit.
  2. The recovery rate, that is the amount of time your water heater takes to heat water in under an hour.
  3. The physical space it takes to operate properly.
  4. And its energy efficient rating.

Before you replace your water heater, it’s good to check its specifications, warranty details, and other helpful information. By doing this you will know exactly what to look for in the next unit. Information such as tank capacity, installation instructions, model number, etc. are more important than you think.

Maintaining A Water Heater

Once you buy a water heater, you can either schedule a professional to come check and repair common issues. Or you can do it yourself! Maintaining a water heater isn’t easy, but after this guide you will get the hang of it without any error.

Following are the certain parts of a water heater that requires maintenance. Before we begin, always wear durable gloves when performing the following steps.

Pressure valve

All water heaters come with a handy pressure valve that helps release pressure when the tank gets over-pressurized. Without it, the water heater unit may explode due to excess pressure build up.

  1. Cut off the power to the water heater. This includes turning off the gas flow for a gas model.
  2. Turn off the water inlet to the water heater that is responsible for collecting cold water.
  3. Place a small bucket under the pressure valve. Once you turn the valve on, some air and water will release from the valve.
  4. Remove the discharge pipe, if the valve isn’t releasing any water.
  5. If there isn’t any air or water release, empty the tank and unscrew the pressure valve from the unit. You can replace it with a new valve of the same dimensions. Use a tough wrench to tighten the screws in place.
  6. Attach the discharge pipe and restart the unit to check if it’s working properly.

Flushing the water heater

This is an important step that most homeowners should know about. It helps alleviate common water tank problems while increasing its shelf life.

  1. Cut off the power to the water heater. This includes turning off the gas flow for a gas model.
  2. Turn off the water inlet to the water heater.
  3. Attach a hose to the drain valve. Make sure the garden hose is durable enough to sustain hot water.
  4. Keep the pressure valve open and allow the water heater tank to empty completely. If there are any left-over sediments along the edge of the tank, it’s important to drain them too.
  5. Shut the drain valve immediately, remove the garden hose, and shut the pressure valve. Keep the hot water spigots open, while letting cold water into the tank.
  6. As soon as the cold water starts to fill up inside the tank, slowly close the hot water spigots and turn on the power to the water heater. This includes turning on the glass flow for a gas model.

For leakage

Any sort of leakage in a home is usually caused by a broken water supply system. With proper insulation, high-quality pipes, and fittings can you ensure no leakages. You can hire a professional to install compression fittings to prevent leaks and drips. They’re a safer and tougher alternative to copper pipes.

In case the water heater’s pressure valve is leaking, it requires proper thermal protection/insulation. So opting for a thermal expansion water tank for eliminating any pipe drips is needed.

On an ending note, it’s good to know that using a brand-new water heater for the first time may cause condensation. No need to worry, it’s completely normal for a heater to release water in the drain pan. This goes away after the water heater has reached its optimal heating temperature.


So can you tackle water heater installation and maintenance? Here are some of the questions you need to ask yourself before choosing a new water heater.

  • Are you well-equipped to replace your old water heater? If so, make note of all specifications of the old water heater such as the capacity, energy efficiency rating, model number, warranty, etc.
  • Can you handle the task on your own? It’s always good to have assistance to physically handle a big unit.
  • Do you have installation tools such as wrenches, pliers, and screwdrivers at your disposal?
  • Replace a water heater takes time, do you have enough time to replace and install a water heater the correct way? Because there’s no chance you can leave the installation procedure unfinished.
  • Are you willing to invest in water heater maintenance, for at least 3 times a year?

Using a water heater requires little maintenance. You need to ensure the water heater tank is rid of corrosion, bacteria, and other contaminants. This enhances efficiency and the heating element doesn’t catch rust. The pressure valves and water inlet system of a water heater need to be well insulated for long-term use.

Lastly, the thermostat needs to be accurate enough to display the right settings to prevent overheating or over-pressurizing the tank.

All these little details make a huge impact on a water heater. So it’s your responsibility to take complete care of it. If you haven’t used a water heater, you may have to spend a bit more for remodeling your basement, in case you’re buying a large storage tank unit. You may even have to spend a little extra to boost energy efficiency so as to avoid paying costly energy bills in the future.

This buying guide offers all the helpful tips and advice you need to move forward. This is a comprehensive guide of all factors to consider and it will, without a doubt, save you time in conducting your own personal research.

If your goal is to buy something valuable and efficient, investing in a good model based on science is ideal. Still, when price is a major factor of consideration for you, buying a small, tankless water heater is better than settling for something that lasts for a short period of time.