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Boiler Vs Water Heater: What’s The Difference?

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Tim Rhodes

Must be wondering the answer to the question boiler vs water heater what’s the difference? 

For most people, hot water is not a luxury, but an indispensable element for daily activities such as cooking, bathing, and washing. 

Your home needs an efficient water heating system, such as a boiler or water heater.

But, what exactly is the difference between a boiler and a water heater? 

Is a boiler the same as a water heater?

No, not really, so what is the difference between a boiler and a water heater?

Although both heat water, as the names suggest, boilers and water heaters do so in different ways.


What Is A Boiler?

Some homeowners may be confused about the difference between a boiler and a water heater. 

I’m going to describe the difference in more detail and analyze the two devices so that you can understand what goes on behind the scenes to heat water or, in the case of boilers, to heat your water and your home.

There is a similarity in the role of boilers and water heaters, but they are not identical.

These devices heat the water you and your family use, although, boilers heat your home, while water heaters do not.

The name is a bit misleading because a boiler does not boil water. Instead, a boiler turns water into steam. 

Boilers can be used not only to heat water but also to heat your home and even to produce energy.

Boilers heat water quickly and are available in both tank and tankless versions, just like water heaters. 

However, unlike water heaters, some boiler systems are equipped with a hot water tank.

(Note: Tanks contain cold water in the case of boilers, while cylinders contain hot water).

How Does A Boiler Work?

Boilers can, of course, be used to heat drinking water. 

However, when a boiler is used to heat a home, it relies on the thermostat to tell when to start boiling water in your home. 

Most boilers are closed-loop, which ensures that when they send steam into the house, they are not continually using freshwater. 

Instead, they start inside the boiler with gas. It is heated indirectly by a combustion chamber.

When the water is turned into steam, the boiler sends it through the house, heating the walls or floor of the house.

High Pressure Versus Low-Pressure Boilers

When buying a boiler, a distinction can be made between high-pressure and low-pressure systems. 

However, if you are considering installing a boiler for your home, you don’t have to make a choice. 

Low-pressure systems are standard in residential heating applications.

High-pressure units for water above 160 PSIG are standard in commercial applications and require frequent monitoring because they can pose safety concerns.

Standard And Combination Systems

A standard boiler system in a house would consist of a cold water tank and a hot water tank. 

This system has a reasonably large footprint but works well for larger homes or families that use a lot of hot water, especially at the same time.

A standard boiler system in a home would have a cold water storage tank and a hot water tank.

This system has a relatively large footprint, but it works well for large homes or families that use a lot of hot water, especially at the same time.

Another option to consider is the combi-boiler.

This type of boiler heats your home in the same way as a standard boiler.

But instead of storing hot water for access through the taps and appliances in your home, it heats water on demand when you need it.

By removing the storage tanks, these boilers take up less space. 

Combination boilers can be considered an option similar to tankless water heaters, which we will discuss later. 

The difference is that being boilers, they also heat your home.

Different Types Of Boilers


Combination boilers provide hot water and heating for your home. 

There is no cold-water tank or hot water boiler, so you need little space.

And it provides fresh water at will.


A system boiler does not require a cold water tank but a hot water tank.

The water comes directly from the main tank and is then heated and stored in your cylinder.

Its size limits hot water capacity – there are options for this – and if it runs out, you will have to wait for the cold water to be heated and stored again.


The traditional boiler is equipped with a cold water tank and a hot water tank, which allows it to take up more space.

It is perfect for large houses, where you can open several tabs at the same time. 

For example, one person can do the dishes, and another can shower or do laundry.

Condensing Boilers 

Condensing boilers are not a type of boiler, but rather an attribute that a boiler can have.

Condensing boilers are often more efficient than other types of boilers.

They retain heat from flue gases present in non-condensing boilers to remove harmful gases generated by heating water with gas.

Maintaining A Boiler

Proper maintenance will ensure the longest possible life of your boiler.

If you are responsible for the maintenance of a boiler, these are the areas you will want to focus on:

  • Keep the ventilation ducts and chimneys clean if you have any
  • Check the water level every month – lack of water can cause severe damage
  • Check for leaks
  • Descaling – hot water causes limescale to build up, which you want to clean up
  • Lubricate moving parts every six months
  • Rinse all the water every six months and clean it thoroughly

Not to be confused with boilers, water heaters have a different function than boilers.

What Is A Hot Water Heater?

Water heaters are more cut and dry than boilers because they have only one task – to heat drinking water.

This water would then be used for bathrooms, washing machines, dishes, and much more.

How Does Water Heater Work?

There are two types of water heaters: water heaters with a tank and water heaters without a container.

A tank water heater takes cold water at the inlet and heats it indirectly inside the tank with a gas burner or electric heating bars. 

The water heater holds it in the tank until the water has reached the correct temperature, waiting for the sink or shower to turn on. 

The water heater “sends” hot water, mixes with the cold water, to your sink or shower, depending on how much hot water you turn on the handle. 

This is done by pressure in pipes – the sink/shower is turned on, cold water is poured into the water heater, and hot water is pushed through pipes and to the faucet.

tankless water heater heats water instantly instead of storing it in a tank. 

When you turn on the water and set the appropriate temperature, a tankless water heater can heat the water that goes into the shower or sink as long as the water is running.

Different Types Of Water Heaters

Conventional water heaters and tankless water heaters are the two main types of water heaters, but other forms of water heaters are also discussed below.


Conventional water heaters are equipped with a tank where water is stored and heated by both gas and electricity. 

The clean, cold water enters through the bottom of the tank and is heated to a specific temperature where it remains ready for use.


Tankless water heaters, also known as “on-demand” water heaters.

This compensates for the fact that no hot water is stored, so they require less space.

There are other types of water heaters:

Heat Pump / Hybrid

Heat pumps or hybrid water heaters are also more energy-efficient than other forms of water heaters because they use heat from the ground or the air. 

But keep in mind that this makes cold spaces the wrong choice for these types of water heaters.


For use with solar thermal panels (which do not produce electricity) that heat from the sun and transfer it to your water heater.

It is best to use them in colder, sunnier areas.

Maintaining A Water Heater

Unlike boilers, water heaters require maintenance to operate more efficiently to extend their lifespan. 

This means daily draining, flushing, water drainage, etc., alone or by a specialist.

  • Check the valve – make sure the power is off, and the water valve is blocked
  • Briefly lift the tab, let some water out, and release

The water flow should stop.

If not, you will have to remove the valve.

  • Check the anode rod – the main thing you are looking for is calcium

If it is coated, you will need to clean it.

  • Empty the tank and remove the sediment – empty the water into a bucket, then leave some freshwater in the tank to mix with the sediment at the bottom

Repeat until the water entering the bucket is clear.

  • Adjust the temperature – lower temperatures will save you money
  • Locate the temperature dial on the side of the tank and turn it with a flat screwdriver
  • Insulate the pipes – warm pipe insulation helps retain heat, while cold insulation prevents condensation in hot weather

Make sure the foam insulation on the pipes matches the diameter of your pipes.

  • Insulate the heater – using an insulating blanket, cover everything except the controls and tops of oil or gas heaters 
  • Secure the edges of the tank with tape

Home Warranties – What’s The Difference?

A boiler is used to heat a home using steam and radiant heat techniques. 

A water heater heats the water that will be used for cooking or cleaning.

Sometimes some people wonder why a home warranty may cover a water heater, but not the boilers.

While boilers are common to heat in countries like Australia and the United Kingdom, they are less commonly used in the United States. 

Water Heaters And Home Warranties

Household warranties on water heaters generally provide coverage.

If a water heater fails, the homeowner will call the home warranty department, and a consultant will be called by the homeowner to diagnose the water heater’s malfunction.

If the malfunction is covered under their home’s program and warranty, the contractor must repair or remove the water heater.

Comparison Between A Boiler vs Water Heater

In addition to looking at the comparison between boilers and water heaters.

We can also compare some different aspects of these appliances, including energy efficiency, installation costs, typical service life, and maintenance requirements.


One thing some homeowners may want to know is whether a water heater or boiler is more efficient.

To answer this question, let’s first examine where boilers and water heaters get their energy.

The fuel sources for boilers are natural gas, propane, fuel oil, and alternative fuels.

Water heaters are generally based on electricity, natural gas, or propane, although some models can run on solar energy.

In terms of performance, it is difficult to make a direct comparison between boilers and water heaters, as performance in both cases varies from one model to another.

Manufacturers generally calculate the boiler efficiency in terms of annual fuel consumption, which indicates the proportion of the energy used by a boiler that is directly converted into heat.

It is also important to remember that you need another furnace for your home with a water heater.

When you want to compare the amount of energy you can use directly from a furnace versus a water heater.

You need to remember the additional energy used by an oven or other heating system in your home.

Installation Cost

Some homeowners would also like to know, “Is it cheaper to install a water heater or boiler? ”

The cost of installing one of these systems depends on several factors, but in general, the installation of a boiler is a more considerable investment. 

Considering both the price of the unit itself and the labor required to install it, a new boiler tends to cost between $3,500 and $8,000.

For water heaters, construction costs appear to be between $1,000 and $3,500, including machinery and labor. 

Installations with tankless water heaters will cost more than other water heater options.

Some homeowners wonder if they can save a little money by buying the unit they want and installing the system themselves. 

Whether building a boiler or a water heater, HVAC experts must be qualified to operate the unit. 

In some cases, attempting to install your boiler or water heater may also void the warranty.

When you use licensed contractors to do the work, you can be sure that they can install the unit safely and under local and national building codes.


Boilers and water heaters are close in terms of service life.

Conventional gas boilers and standard water heaters tend to last 10 to 15 years.

When your primary concern is longevity, you will want to choose a high-quality boiler or water heater and keep it in good condition.

In addition to do-it-yourself maintenance, have your boiler or water heater serviced by a professional whenever you need it.

Another thing to note for homeowners who are particularly interested in longevity is that tankless water heaters often have a longer service life.

If properly maintained, they tend to last more than 20 years.

Also, they last an incredible amount of time because they are easily replaceable parts.

You don’t always have to wait until a boiler or water heater stops working to repair them.

In some cases, you may want to upgrade your water heater or boiler, even if it is still running after a while because there are newer, more energy-efficient versions available.

Maintenance Required

Let’s look for a moment at the boiler and water heater maintenance activities that you will need to take care of. 

Both systems may require some maintenance, but water heaters, on the other hand, seem a little less easy to maintain.

To prolong a boiler’s life, you will need to:

  • Inspect it periodically to ensure that water levels are in place and that there are no leaks
  • Regularly clean all nozzles and chimneys and decalcify lime accumulation as required
  • Rinse the machine thoroughly and vacuum every six months
  • Lubricate moving parts twice a year

For water heaters, especially those with tanks, you will need to do this regularly:

  • Inspect the water heater for leaks or other problems
  • Test your water faucet by turning it off to make sure the flow stops as it should
  • Empty the tank and remove any debris that has accumulated inside

Do You Need A Boiler Or Water Heater?

There are as many similarities as differences in the choice of boiler and water heater. 

This makes it challenging to choose the right option for your home and your individual needs.

Ultimately, it depends on individual circumstances and choices. 

There are a few essential factors to consider when choosing a boiler or water heater:

  • What is the climate you live in
  • How much space do you have
  • How many people will use the water supply from your system
  • Do you need access to hot water on demand

The only constant is that the hot water heating system you choose should easily last between 10 and 20 years – or more – with proper maintenance and care!

You could, of course, save time, money and trouble, and give up hot water altogether.

After all, who in mid-December doesn’t like cold showers?

If you’re not the type to take a cold shower but are thinking about replacing your boiler or water heater.

You’re probably thinking about the cost of a water heating system.

They are not at all uncomfortable, unlike cold showers.

And with lower interest rates than other traditional financing options, you may have a little more money to enjoy than a boiler or water heater!

When Does A Water Heater Become A Boiler?

Many people use a radiant floor water heater instead of a boiler because it costs less. 

When used in this way, a water heater saves energy.

The cost is essential, but there are several other fundamental factors as well.

A high-quality water heater is more energy-efficient and more environmentally friendly.

For many years of trouble-free operation, quality water heaters can be made of stainless steel.

It is important to remember that the same cannot be said of poor quality water heaters that are economical.

The radiant heat from the groundworks with hot water.

Boilers are designed to produce radiant heat with boiling water.

Many are not able to operate well at lower temperatures and need expensive additional components to distribute the water without damaging the lower temperatures. 

Many boilers are prone to “thermal shock” damage when water at room temperature is returned in abundance when it is turned on unless more expensive components are added.

But water heaters are designed to operate at lower temperatures from the start. 

Lower temperatures are excellent for production.

Because of their low operating temperature, modern water heaters can condense exhaust gases into the water in a simple, non-mechanical way.

Boilers are designed to boil and not condense, just like a unit designed to operate at low temperatures.

The answer to the boiler vs water heater?

There are many similarities and variations with all water heaters and boilers available on the market.

This makes it challenging to choose the best choice for your home and your individual needs.

Final Thoughts

Finally, the choice between a boiler and a water heater depends on four essential factors:

The environment in which you live, the availability of adequate storage space, the number of people using the system’s water supply, and whether you need hot water on demand.

The only aspect that remains consistent in both cases is the need for proper care and maintenance of hot water systems.

If your bank account can handle a tankless water heater’s higher initial cost, you will save more money over time by choosing the tank.

However, if you have a modest fixed income, a water heater for your storage tank may make more sense.

Discuss both types with your plumber to evaluate your options.

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