How Does a Wood Fired Boiler Work? A Comparison with Gas Boilers

Boilers are essential components of a home's heating system, providing warmth and comfort during colder months. When it comes to choosing the right boiler for your home, there are many factors to consider, including efficiency, cost and environmental impact.

In this article, we will explore the workings of two popular types of boilers: wood fired boilers and gas boilers, and compare their characteristics to help you make an informed decision for your home.

Introduction to Wood Fired Boilers and Gas Boilers

Wood fired boilers and gas boilers are two popular types of heating systems for homes. Both types have their own unique benefits and drawbacks, which can make it challenging to decide which is the best fit for your specific needs. To understand the differences between these two top central heating systems, it's important to first understand the basics of each type of boiler.

Wood fired boilers, as the name suggests, utilise wood as their primary fuel source. These systems have been around for centuries and have seen significant advancements in technology and efficiency in recent years. Wood fired boilers can be an eco-friendly and cost-effective heating solution, particularly for homes in rural or wooded areas with easy access to wood fuel.

Gas boilers, on the other hand, use natural gas or propane as their fuel source. These systems are more common in urban and suburban areas, where natural gas infrastructure is readily available. Gas boilers offer a higher level of convenience and ease of use compared to wood fired boilers, but they may not be the most environmentally friendly option depending on the source of the natural gas.

Other types of boiler include biomass boiler, oil boiler, outdoor wood boiler, pellet boiler and outdoor wood furnaces.

Understanding the Basics of a Wood Fired Boiler System

A wood fired boiler system is composed of several key components that work together to generate heat for your home. These systems can be classified into two main types: log wood boilers and wood pellet boiler stoves. Log wood boilers burn firewood logs, while wood pellet boiler stoves utilise compressed wood pellets as fuel. Both types of wood fired boilers can provide efficient and reliable heating for your home.

The wood fired boiler system starts with the combustion of wood fuel in the firebox, which releases heat energy as the wood burns. The heat generated in the firebox is then transferred to a heat exchanger, which in turn heats the water circulating through the boiler system. The heated water is then distributed throughout your home, providing enough hot water to meet your needs.

Key Components: Heat Exchanger, Boiler Stove and Domestic Hot Water

Heat Exchanger

One of the most important components of a wood fired boiler system is the heat exchanger. It is a device that transfers heat energy from the burning wood to the water circulating through the boiler system. This process is crucial for the efficiency and effectiveness of the wood fired boiler, as it allows all the heat generated by the burning wood to be effectively utilised for heating your home.

Boiler Stove

A boiler stove is another key component of a wood fired boiler system. The wood boiler or stove is essentially the combustion chamber where the wood fuel is burned. It is designed to efficiently burn wood fuel and transfer the heat energy to the heat exchanger. The design of the boiler stove can have a significant impact on the overall efficiency and effectiveness of the wood fired boiler system.

Domestic Hot Water

In addition to providing heat for your home, a wood fired boiler system can also be used to provide hot water for domestic use. This is achieved by integrating a hot water storage tank into the boiler system. The heated water from the boiler system is stored in the hot water tank and can be used for various household needs such as showering, washing dishes and laundry.

In addition to supplying hot water, this central heating system can also be used for providing underfloor heating.

How Does a Wood Fired Boiler Work? Step-by-Step Process

Now that we have a basic understanding of the key components of a wood fired boiler system, let's explore the step-by-step process of how these systems work to provide heat to your home.

1. Fuel Loading: The first step in the process is to load the wood fuel into the boiler stove. This can be done manually for log wood boilers or automatically for wood pellet boilers using a fuel storage and feeding system.

2. Combustion: Once the wood fuel is loaded into the boiler stove, it is ignited and begins to burn. The combustion of the wood fuel releases heat energy, which is then transferred to the heat exchanger.

3. Heat Exchange: This device plays a crucial role in the process by transferring the heat energy from the burning wood to the water circulating through the boiler system. As the water absorbs the heat energy, its temperature rises. A simple form of a heat exchanger is the back boiler.

4. Circulation: The hot water is then circulated via a pump throughout your heating system, typically through a series of pipes and radiators. As the water passes through the radiators, it releases more heat energy into the rooms of your house.

5. Return and Reheating: Once the hot water has circulated through your home's heating system, it returns to the boiler to be reheated. This process continues until the desired temperature is reached and maintained in your home.

Understanding the Basics of a Gas Boiler System

A gas boiler system operates similarly to a wood fired boiler system, with a few key differences. The main difference between the two systems is the fuel source used to generate heat. In a gas boiler system, natural gas or propane is burned to release heat energy, rather than wood fuel.

Gas boiler systems can be classified into two main types: conventional (or non-condensing) boilers and condensing boilers. Conventional gas boilers release heat energy through the combustion of natural gas, while condensing boilers are designed to additionally capture and utilise the heat energy in the water vapour produced during combustion. This makes condensing boilers more efficient and environmentally friendly compared to conventional gas boilers.

You can more easily control a gas fuelled boiler electronically with a programmer, meaning that the system can be left unattended to maintain a pre-set temperature. A modern boiler stove usually has an electronic programmer.

Key Components of a Gas Boiler: Heat Exchanger and Domestic Hot Water

Heat Exchanger

The heat exchanger in a gas boiler system plays the same crucial role as in a wood fired boiler system, transferring heat energy from the combustion process to the water circulating through the boiler system. The efficiency can have a significant impact on the overall efficiency and effectiveness of the gas boiler system.

Domestic Hot Water

Just like wood fired boiler systems, gas boiler systems can also be used to supply domestic hot water. This can be achieved by integrating a hot water storage tank or alternatively, an on-demand water heater into the boiler system (combination system). The hot water from the boiler system and buffer tank can then be used for various household needs, such as washing dishes, taking a bath and doing laundry. The central heating can even be connected to underfloor heating.

How Does a Gas Boiler Work? Step-by-Step Process

The process of how a gas boiler works to heat water in your home is similar to that of heating hot water using a a wood burning stove or wood fired boiler, with a few key differences. Let's explore the step-by-step process of how a gas boiler system operates.

1. Ignition: The first step in the process is the ignition of the natural gas or propane fuel. This is typically achieved using an electronic ignition system, which ignites the gas fuel when the boiler system calls for heat.

2. Combustion: Once the gas fuel is ignited, it begins to burn and releases heat energy. This heat energy is then transferred to the heat exchanger, where it is utilised to heat the water circulating through the boiler system.

3. Heat Exchange: This plays a crucial role in the process by transferring the heat energy from the burning gas to the water circulating through the boiler system. As the water absorbs the heat energy, its temperature rises.

4. Circulation: The heated water is then circulated by a pump throughout your home's heating system, via a series of pipes and radiators. As the hot water passes through the radiators, it releases heat into the rooms, warming your home.

5. Return and Reheating: Once the hot water has circulated through your home's heating system, it returns to the boiler to be reheated. This process continues until the desired temperature is reached and maintained in your home.

Comparing Wood Fired Boilers and Gas Boilers: Efficiency, Cost & Environmental Impact

When it comes to choosing between a wood fired boiler and a gas boiler, there are several factors to consider. One of the most important factors is efficiency. Wood fired boilers can be highly efficient, with some models boasting efficiency ratings of up to 90%. However, the efficiency of a wood fired boiler can be impacted by factors such as the quality of the wood fuel and the design of the system.

Gas boilers, on the other hand, are typically more efficient than wood fired boilers, with some models boasting efficiency ratings of up to 98%. This is due to the fact that natural gas or propane fuel burns more cleanly and efficiently than wood fuel.

Another factor to consider when comparing wood fired boilers and gas boilers is cost. Wood fired boilers can be a more cost-effective heating solution, particularly for homes in areas with close access to well seasoned wood. This is very dependent on location and availability because these two factors influence the economic efficacy of this heating option.

Gas boilers, on the other hand, can be more expensive to install and maintain than wood fired boilers. However, the cost of natural gas or propane fuel can be more stable and predictable compared to the cost of wood fuel.

Finally, it's important to consider the environmental impact of wood fired boilers and gas boilers. Wood fired boilers can be an eco-friendly heating solution, particularly if the wood fuel is sourced sustainably. However, the emissions from burning wood and particulate matter can contribute to air pollution and can be harmful to the environment if outdoor wood boilers are not properly managed. Note that old style wood burning stoves might be prohibited in smoke control areas. A modern wood burner may be classified under exempt appliances.

Gas boilers, on the other hand, can contribute to greenhouse gas emissions and can have a negative impact on the environment if the natural gas is sourced from non-renewable sources.

Choosing the Right Boiler for Your Home: Factors to Consider

When choosing between a wood fired boiler and a gas boiler, there are several factors to consider to determine which type of boiler is the best fit for your specific needs. Some of these factors include:

• Location: If you live in a rural or wooded area with easy access to own wood, a wood fired boiler may be a more cost-effective and eco-friendly heating solution.

• Efficiency: If you prioritise efficiency and want to minimise your carbon footprint, a gas boiler may be the better option.

• Cost: If you are on a tight budget and want to minimise your heating costs, a wood fired boiler may be a more cost-effective option that will help you save money in the long run.

• Convenience: If you prioritise convenience and ease of use, a gas boiler may be the better option.

Ultimately, the decision of which type of boiler to choose will depend on your specific needs and priorities.

Conclusion: Weighing the Pros and Cons of Wood Fired Boilers and Gas Boilers

In conclusion, both wood fired boilers and gas boilers can be effective heating solutions for your home. Wood fired boilers can be a more cost-effective and eco-friendly option for a central heating system, particularly for homes in rural or wooded areas with easy access to wood. Gas boilers, on the other hand, can be much more fuel efficient and convenient, but may not be the most environmentally friendly option depending on the source of the natural gas.

When choosing between a wood fired boiler and a gas boiler, it is important to weigh the pros and cons of each type of central heating system and consider your specific needs and priorities. By doing so, you can make an informed decision and choose the heating solution that is best for your home.