Boiler vs Water Heater – Find Out Which One is Right For You

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Boiler vs Water Heater

Boilers and water heaters have a few things in common: they heat the water you use in your home. However, they are two different home appliances, with several differences that set them apart.

As a homeowner, it is vital to understand the differences and similarities between boilers and water heaters, so you can purchase the one that suits your needs.

Additionally, understanding how the two appliances work will help you maintain them well so that they serve you for longer. 

So between a boiler and a water heater which do you have in your home, and how does it work? This guide contains the answers and much more on how they heat the water you use in various ways.

What is a Boiler? 

Although it’s called a boiler, its work is not just to boil the water. A boiler is an appliance that heats water and turns it into steam. The steam is then transported through pipes to radiators for spreading heat throughout a home or building. Steam is easily transported throughout your home, making boilers an efficient means of producing heat for your home.

Steam also holds heat better than just air, so your home remains warm for longer. That is why you can use boilers to heat your home efficiently and without using much energy during the colder months.

Apart from heating your home, boilers also heat the water you use when you turn on the shower, dishwasher, and washing machine. That means you will use the same energy-efficiency source for heating your home and hot water.

Most boilers use a closed loop: which means that when the steam cools down, it goes back to the boiler and is reheated, saving water.

Related: Best Space Heater for a Large Room – 10 Models to Consider in 2023

Types of Boilers

When you understand the different types of boilers, it is easy to select a suitable one based on the size of the area it will use, energy consumption, and other factors.

High and Low-Pressure Boilers

High-pressure boilers heat water and steam at very high pressure. They also require regular maintenance checks, so they pose safety risks. They are not recommended for residential buildings.

On the other hand, low-pressure boilers heat water at lower pressures, making them safe for your home, school, or office. With low-pressure boilers, you only need to call in a maintenance crew when they start to break down.

Standard Boiler and Combination Boilers

A standard boiler set-up has two tanks: one for cold water and another for storing hot water. This makes this setup quite sizable and not ideal for you if you are working with a small space. This setup is used by people who use a lot of water, such as households with many members and apartment buildings.

Combination boilers, aka combi-boilers, heat water the same way as a standard boiler, so what’s the difference? While a standard boiler heats and stores the water, a combi-boiler heats the water when needed. This setup is similar to a tankless water heater, as we will see below.

Not storing hot water means combi-boilers take up less space. So as long as you don’t use a lot of water and have limited space, a combi-boiler will work.

Boilers Pros and Cons

Boilers Pros Boilers Cons
Energy efficiency Cannot cool your home
Even heat Expensive 
Does not dry air It takes time to adjust the temperature

when a thermostat setting is altered

Quieter than other house heating methods  
Little maintenance  

Benefits of Boilers

Boilers don’t have ducts that can collect dust and don’t move air about or dry it. Therefore, a boiler system improves the air quality in your home.

We are at the age of environmental conservation, ensuring we do not misuse non-renewable resources. That is why modern boilers have been improved to ensure they use less energy. A boiler produces a lot of steam using little oil or gas.

They require little maintenance and can serve you for decades with little maintenance and minor repair.

Boilers provide even heat throughout your home, and the heat is easy to control. All you need to do is turn on the thermostat, set the temperature, and get consistent heat until you decide to adjust it.

Drawbacks of Boilers

Boilers can only warm your home, so you will need to install another device for cooling your home. This means additional buying and installation costs.

Old faucets and plumbing work can lead to leakages. This leads to water damage to your homes, such as mold growth, peeling paint, and stains on ceilings.

Boilers may take too much time to adjust your home’s temperature when the thermostat setting is altered.

Additionally, don’t expect instant heat because it takes time to heat the water into steam.

Installing boilers takes time, especially retrofitting the radiators and pipes. Installing boilers is like an investment because of their durability. However, this comes at a high price.

What is a Water Heater?

Water heaters are home appliances that play one role in your home: heating water for various uses. So you can get hot water from heaters for taking a bath, the dishwasher, shower, and washing machine.  So if your source of hot water in your home is a water heater, you will need to find another alternative for heating the house.

You can set up heat pumps, a furnace to heat your living space, and a water heater for all your hot water needs.

Related: Heat Pump Water Heater Vs. Tankless Water Heater

Types of Water Heaters

There are two typical water heaters in the market: tankless water heaters and tank water heaters. Both heaters heat water for use in the home; however, one is tankless, while the other has a tank.

Tank Water Heaters

This is the standard water heater in the market—the tank heats and stores hot water that can be used anytime. Therefore anytime you turn on the hot water faucet, the hot water travels from the tank through your home plumbing system. 

As the hot water leaves the tank, it is replaced with cold water that gets heated and ready for use.

Tankless Water Heaters

Tankless water heaters are similar to combination boilers because they don’t have a storage tank for hot water. Therefore the water gets heated when you turn on the hot water faucet. Apart from using less space, a tankless water heater uses less energy than a tank water heater.

Benefits of Water Heaters

Water heaters require little maintenance, so you don’t have to worry about maintenance costs once you incur the purchasing and installation costs. 

There are electric and gas water heaters. That means you can choose a water heater based on which energy source is readily available.

Water heaters do not take up much space, so they are a good choice, even if you have limited space. Additionally, their shorter life span means you do not have to worry about water damage.

Drawbacks of Water Heaters

If you use an electric water heater and power goes out, so does your hot water supply. 

Water heaters only heat water for household use, so you need to think of alternative means of warming and cooling your house.

If you have a tank water heater, it can run out of hot water if many people use the water within a short time frame.

Boiler vs. water heater

  Efficiency Cost  Lifespan Maintenance
Boiler Efficient  Higher purchasing and installation cost Up to 30 years High maintenance
Water heater Efficient  Lower purchasing and installation cost 15-20 years Lower maintenance

Comparing Boilers and Water Heaters

Understanding the differences between a boiler and a water heater in terms of their functions is essential before buying them. It’s also vital to know how they compare in other aspects, such as lifespan and cost.

Boiler vs. Water Heater Efficiency

Energy efficiency is an important aspect to consider when buying and installing home appliances. Although it is hard to say between a boiler and a water heater, it is vital to remember that a boiler serves two roles: heating your water and warming the home. 

On the other hand, a water heater only solves your hot water needs. That means you need an alternative heat source that will increase energy consumption.

Boiler vs. Water Heater Cost

We have a clear winner when comparing costs: purchasing and installing a water heater is cheaper than a boiler.  You may spend between $1000 to $3500 to buy and install a water heater, while the total cost of purchasing and installing a boiler can be up to $8000.

Boiler vs. Water Heater Lifespan

Although it is more expensive to install a boiler, you can consider it a good investment. Why? Because while a water heater can last between 10 to 15 years, a boiler can last for 2 or even 3 decades with good maintenance.

Boiler vs. Water Heater Maintenance

You can improve the lifespan of boilers and water heaters with proper maintenance. Here are tips for increasing boiler lifespan:

  • Inspect water levels annually and make sure there are no leaks
  • Clean and flush the system twice per year
  • Lubricate the moving parts every six months.

Water heaters are low maintenance than boilers:

  • Inspect the tank for any leaks and drain the tank and remove sediment
  • Switch off the power and check the valve to make sure it stops the flow 

Boiler vs. Water Heater BTU

Most boilers range between 75,000 to 180,000 BTU/hr. On the other hand, a residential water heater can range from 40,000 to 60,000BTU/hr. 

Radiant Heat Boiler vs. Water Heater

Water heaters cannot warm spaces and do not heat water to very high temperatures; thus, they produce little radiant heat. Boilers, on the other heat the water to a very high temperature; thus, they produce a lot of radiant heat.

Water Heater vs. Boiler vs. Furnace

Water heaters and boilers share one thing: they are both used for heating water in your home. However, a boiler and a furnace are both used to warm surfaces, so they are a source of heat when it’s cold.

While boilers use steam(after boiling water) to warm surfaces, furnaces use air. Boilers require little maintenance, while furnaces need more maintenance. Also, furnaces move air, reducing the air quality in your home.

Boiler vs. Tankless Water Heater

Tankless water heaters and boilers are more expensive to install than tank water heaters. With both appliances, you cannot run out of cold water because a tankless water heater and boilers boil water on demand, while standard boilers have a separate hot water tank.

Boiler and Water Heater Combo

A boiler and water heater combo uses one appliance to heat water and warm your living space. It functions as a tankless water heater(heating water on demand), but you can also switch on the space heating option; therefore, it needs a smaller space.


For homeowners, having a reliable hot water supply means cleaning dishes well, running the washing machines when you want, and warming up with a hot bath or shower. You can do all that with a boiler or water heater.

However, a boiler also warms up your home during the cold winter so that you and your family can be warm, cozy, and safe from the harsh cold. Once you have installed your boiler or water heater, follow the maintenance tips to ensure you increase the lifespan of your boiler or heater.

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