How To Choose A Water Heater

There’s nothing more uncomfortable than a water heater breaking down, leaving you with cold water when you least expect or need it! Whether you’re dealing with an unexpected breakdown or have planned for some time to upgrade the whole system – choosing the right water heater is key.

Whether it’s installing a new or replacing an old water heater, compare all information first. You’re in the right place to discover all the ins and outs of this type of purchase for your home in this comprehensive buyer guide below.

Content Table

What size water heater do I need?

When choosing the type of water heater, you first need to consider its size, as this determines its heating capacity and ensures it can meet your family’s hot water needs.

Let’s say you consider a tank heater (conventional or heat pump type). You need to determine how many family members will be using this, and you can estimate the needed tank volume (for gallons) based on that information:

  • 1–2 people – around 30 gallons for normal/low demand, and 40 to 50 gallons for high
  • 2–4 people – around 40 gallons for normal/low demand, and 40 to 50 gallons for high
  • 3–5 people – around 40 gallons for normal/low demand, and 50 to 75 gallons for high
  • 5 or more people – around 50 gallons for normal/low demand, and 75 gallons for high

Besides tank capacity, you also want to calculate the FHR (first-hour rating). FHR tells you how much hot water you can get from the tank in just one hour of heating it gets. This tells you how efficient the water heater is in peak use (especially when you are in a hurry and need to shower, for example!). 

For you to estimate the demand in peak hours, first decide when in the day you use hot water the most (morning, noon, night). After that, you can use various accessible charts or calculators to find out how much of this you use. But, let’s take a look at rough numbers:

  • Washing hands (per person): around 2 gallons
  • Bathing or showering (per person): around 20 gallons
  • Washing hair (per person): around 6 gallons
  • Running washing machine: around 30 gallons
  • Shaving: around 3 gallons
  • Running the dishwasher: around 14 gallons

If someone from your family showers in peak hours, and another is washing hands, but you also loaded the dishwasher and maybe laundry too, then don’t look for anything below 66 gallons FHR minimum (20 + 2 + 14 + 30 = 66).

Now, let’s say you have a tankless water heater. These are super convenient because they will heat the water when needed, and they don’t store it endlessly. Pay attention here to the needs of your household, the desired temperature, and the flow rate.

Let’s first determine the peak hot water demand. For this, you need to list all the appliances and fixtures that you use simultaneously. There is a flow rate for each of these, measured in GPM (gallons per minute):

  • Dishwashers: 1-2 GPM
  • Washing machines: 2-2.5 GPM
  • Showers: 2-3 GPM
  • Kitchen sinks: 1-1.5 GPM

Now just gather all sums from all fixtures and you get a total flow rate. Easy as that!

Next, you need to determine the rise in temperature. Try to estimate how much cold water is used in your home (this will often depend on the season and region), but let’s say circa 50°F. Now set your desired temperature (usually for most appliances this is circa 110-120°F).
Do you want to know how to calculate the rise in temperature? It is easy, just subtract the incoming water temperature from the desired one. If the incoming is at 50°F, but you want 120°F, the total calculation for the rise is 70°F.

Now it’s time to calculate the heater capacity after you did the math above. Look for the info from a manufacturer in matching flow rate and rise in temperature. Here is one simple formula in BTUs:

Heater Capacity (BTUs/hour)=Flow Rate (GPM)×Temperature Rise (°F)×500

Let’s say you need a flow rate of 6 GPM and a temperature rise of 70°F, then:

6 GPM×70 °F×500=210,000 BTUs

If we assume you have two showers (each of 2.5 GPM), a dishwasher (1.5 GPM), and a kitchen sink (1.5 GPM) and use them at the same time, your flow rate will be 8 GPM. So if the incoming water is 50°F, and you want 120°F, you need a rise totaling 70°F. So, you would choose a tankless water heater that comes at a minimum of 280,000 BTUs (8 GPM × 70°F × 500) for peak demand.

Always ensure that you see the tools and charts of manufacturers if you want to find the ideal model for you. For the best results and help with this, consider consulting a local water heater service contractor to help you find the perfect fit for your home.

How to choose a water heater

 There are a variety of factors to keep in mind, such as:

  1. Fuel Source: Do you use gas or electricity, propane, or another fuel type?
  2. Type of Heater: Each type has its benefits and drawbacks that you must compare to make your best final decision. 
  3. Capacity: Assess your home’s hot water needs first. 
  4. Space Requirements: Consider where the water heater will be installed. 
  5. Water Heater Size: Match the size of the water heater to your household’s demand. 
  6. Quality Contractor: For all doubts, a reputable plumbing contractor from Ace will be happy to help!

Now that you know what to consider, let’s look at water heater types.

What is the best water heater?

This depends on the types of water heating energy they use and which you prefer for your specific home needs. Each type has its own advantages and considerations – it’s up to you to revise them, and we can further help you make the most of your decision and purchase. 

Picking out better appliances to install in your household can be simpler when you get the right know-how and guidance.

It’s also important to consider the fuel your future water heater needs. Some options are more energy-efficient than others and help you cut down on costs. Gas and liquid fuel models, for example, lose a lot of energy because they need to ventilate a lot as well. So, remember to keep fuel type in mind before purchasing.

Electric Water Heaters

Electric water heaters use electric resistance coils to heat the water. This process is controlled by thermostats that regulate the water temperature on these electric models. 

Pros
Cons
  • Affordable 
  • Easy to install
  • Clean
  • Easy to maintain
  • Suitable when gas or oil is unavailable
  • Higher operating costs
  • No hot water during a power outage
  • Longer time to restore hot water
  • Require electrical system upgrades
  • For older homes: It may be needed to replace the electric panel and wiring to connect with high amps

Gas Water Heaters

Gas water heaters use natural gas or propane as a fuel source to heat water. When the thermostat senses that the water temperature has dropped below the desired level, it ignites the burner in gas models, heating the water directly.

Pros
Cons 
  • Provides more hot water / faster reheating time
  • Faster reheating time
  • Highly energy efficient
  • Gas is cheaper than oil
  • Operational during power outages
  • Complicated to maintain and install
  • Installation location constraints (depending on ventilation options)
  • More components to handle when it malfunctions
  • Requires regular flushing (unless you want sediment build-up!)
  • Periodic gas line and cylinders checks (to avoid any leaks)

Oil Water Heaters

Oil water heaters use oil as a fuel source to heat water. The oil is stored in a tank and pumped into a burner to ignite and heat water in the tank. 

Pros
Cons
  • Faster heating time than other models out there
  • Highly energy efficient
  • Long lifespan
  • Higher service and maintenance costs than gas/electric
  • Additional cleaning needed
  • More expensive to install than others
  • Require constant fuel supply

Heat Pump Water Heaters

A heat pump water heater heats water by transferring heat from the surrounding air to the water in the tank. This type operates in two modes, providing flexibility in different conditions: 1) Heat pump mode 2) Electric resistance mode.

Pros
Cons
  • More expensive than other types
  • Large size (if your living space is quite small, this is a huge barrier!)
  • Lower average lifespan

Storage Tank Water Heaters

Conventional water heaters (i.e., storage tank water heaters) are the most common type. They operate by heating water in an insulated tank, which keeps the warmth with its insulation.

Pros
Cons
  • Lower initial cost
  • Efficiency in any climate (tank is well-insulated to sustain any climate temperatures)
  • Lower installation costs (simpler technology and less complex requirements)
  • Increased energy loss
  • Large size (not ideal for small homes)
  • Vulnerable to water damage, it may leak or burst (a problem you don’t want at home!)

Tankless Water Heaters

Tankless water heaters (i.e.,  on demand water heaters) heat water directly without a storage tank. Here,a gas burner heats the water instantly, providing a continuous supply of hot water whenever you need it. There are many benefits of tankless water heaters, but let’s also compare all aspects:

Pros
Cons
  • Instant hot water
  • Space saving
  • Highly efficient
  • Lower monthly costs
  • Affordable to install
  • Higher initial cost
  • Notable energy loss
  • Large size 
  • Limited hot water supply
  • It may be prone to water damages

With all this information on different types of water heating, their benefits, and their considerations, you can plan out your next water heater installation much better and more easily!

Frequently Asked Questions

How to tell if a water heater is gas or electric?

Look for a vent pipe at the top of the unit, which indicates a gas heater because it needs to vent combustion gasses. Gas heaters will also have a pilot light and a gas supply line. On the other hand, electric heaters have an electrical cable and typically no vent pipe or gas line.

Is a tankless water heater better?

A tankless unit is better for some households because it provides instant hot water, saves space, and can reduce monthly energy costs. But remember that they have a higher initial cost and may struggle to meet high simultaneous demand from different water outlets. For example, running hot water from a shower, a faucet, and a washing machine may slow down your system depending on its capacity.

Which is better: gas or electric water heater?

Choosing between a gas or electric water heater depends on your priorities. Gas water heaters generally offer lower operating costs and faster heating times but require proper ventilation and regular maintenance. Electric water heaters are easier to install and maintain and are more suitable for areas without gas lines, but they tend to have higher energy costs.

Water heater efficiency

Before you install a water heater, look at the EF (energy factor), or percent of energy turned into hot water. The higher this is, the better the device!

Yes, high EF is good, but you need to keep in mind the energy cost of heating water. If you are unsure, check the cost of operating the unit before other factors. Check this formula for the payback period if you compare the same FHR heaters but with different prices.

The number of years in the result means the energy savings will offset a higher purchase price in that amount of time. Ideally, you want to aim for a payback period of circa 10 years, which is the usual lifespan of a heater. If the cost of energy rises in the meantime, know that the payback period shortens!

What size tankless water heater do I need?

To determine the size of the tankless water heater you need, calculate the total flow rate (in GPM, gallons per minute) of all the fixtures you expect to use simultaneously. For example, running two showers and a washing machine simultaneously will require a tankless water heater with a higher flow rate than just running two showers.

GPM formula: 60 has to be divided with the amount of seconds it took to fill a gallon container completely. Let’s say you took 20 seconds to fill a gallon. This makes your GPM = 3 (60/20 seconds = 3 GPM)

How big is a water heater for a family of 4?

For a family of four, a storage tank water heater with a capacity of 80 gallons is typically sufficient to meet daily hot water needs.

What size tankless water heater will replace a 50 gallon?

To replace a 50-gallon conventional water heater with a tankless model, you’ll need one with a flow rate of approximately 7.5-9 GPM, depending on your hot water usage.

Go tankless!

Thinking of replacing your old water heater?  Here’s why you should go tankless, in case you need the recap. 

A tankless water heater replacement ensures you’re always getting hot water by instantly heating it as soon as needed rather than constantly keeping a large tank of water hot.

They’re also far more compact, durable, and energy-efficient than traditional units. You check out a few factors simultaneously with this option!

How long does a water heater last?

The lifespan of a water heater varies by type and maintenance, but on average, traditional tank water heaters last 10–15 years, while electric tankless water heaters can last over 20 years with proper care.

How much does a water heater cost?

The cost of a water heater depends on the type and size. For example, a new heat pump water heater typically ranges from $1,500 to $3,000.

What brand of water heater is the most reliable?

Different brands excel at producing different water heater types. For conventional water heaters, A.O. Smith is recommended. Rinnai is well-known for its gas water heaters, and Bosch, Rheem, and Richmond are revered for their heat pump water heaters.

Bring on the hot water!

When choosing a new water heater for your home, make sure it’ll provide enough hot water for your family AND help you save energy and money.

If more than one fuel is available in your area, try comparing fuel costs, specifically if you are building a new home. Even if you simply replace your water heater, you can save more money in the long run by using a different fuel or energy source.