What is a Combination Boiler ?

combination boilerCombination boiler is an efficient technology used for either purpose, known for heating water in some parts of the world, and for heating homes in others. By burning gas, instead of using electricity, boilers harness the power of steam for either home or water heating. In both the U.K. and U.S. these systems have become the chosen preference for hot water demands in small homes and apartments. A combination boiler is often preferred over conventional or sealed-system boilers because of their numerous advantages, including: energy efficiency, on-demand capabilities, compact size, limited maintenance costs, and economical price. They are not right for all families, though, and every option should be considered before deciding which boiler is right for your home.

How Does a Combination Boiler Use Gas to Heat Homes or Water?

In a combination boiler, water is taken directly from the main water line and heated from the steam produced by burning natural gas. Through the use of a dual-heat exchanger all water vapor produced during combustion is captured and put to work, increasing the efficiency of the heating process. This process is a type of condensing technology.

The use of gas over electricity creates a desirable environmental boon as well. When Natural Gas is combusted, it produces similar emissions as oil and coal: carbon dioxide and nitrogen oxides, but the emission levels are much lower. Secondly, condensing gas boilers make use of technology to capture the carbon dioxide released, reusing it in the system, further reducing air emissions. With energy use being one of the largest contributors to air pollution from residential areas, these reductions serve as a benefit to the community as a whole.

What Differentiates a Combination Boiler from Other Available Types?

combination boiler pictureThe three main types of boilers all use the burning of gas to heat water and so function similarly, but they differ in two important ways: how you get water from the tap, and the number of users the system can provide hot water for. In conventional or ‘regular’ boilers, cold water is first heated in a tank or cylinder – producing a bit of a wait time – then that water is made available to any and all of the taps throughout the house that can call upon it. With sealed system boilers many of the components necessary for heating are built directly into the system, but users still need to wait while water is heated in a separate tank. Several faucets may access the water and no interruption is seen when more than one user accesses the system at the same time, but there is still a wait time for hot water. A combination boiler takes up a lot less space, making them similar to the sealed system boilers, but their design allows for on-demand water heating, meaning users have little to no wait time at the tap. But that same design limits the number of users the system can accommodate, resulting in pressure variations if more than one tap is turned on at the same time.

What are some of the Other Advantages of a Combination Boiler?

The dual-heat exchange function built into a combination boiler makes it particularly efficient at capturing the heat of fuel combustion, using it to further the needs of the system. This design means less of this unit’s energy is lost, increasing overall energy efficiency. Now, not all combination boilers are created equally with certain high-efficiency models providing the greatest energy savings over the long run. A qualified professional can help you select the model that works best for your needs.
Due to the tankless design of combination or ‘combi’ boilers, a combination boiler allow users to waste little to no energy on heating a tank or cylinder before heating the water users need. This efficiency extends to the water itself, as well. Water is heated on demand rather than sitting in a tank and being heated several times before it is actually used, like in older conventional boilers. Between the dual-heat exchanger and ‘as needed’ heating, these boilers can increase the efficiency of heating upwards of 20-40% over older conventional systems.

The lack of a tank also makes combination boilers a good bet when space is at a premium. In small homes and apartments a system that can fit in a cabinet leaves more space available for other purposes, and as cities become increasingly congested, this advantage is especially significant.combination boiler view

The energy savings also provides a secondary benefit – a yearly financial savings over older systems or some of the less efficient alternatives, recouping the cost of the system over time. In some cases, an immediate financial benefit can result via public utility vouchers or government tax credits. Buyers should contact their local utilities and review the tax rules and regulations that cover energy efficient appliances and equipment.

The final advantage of combination boilers is that of maintenance. With fewer separate parts to maintain, a yearly service call should suffice to care for your unit. Without a hot water heating tank, the possibility of extensive damage from a broken or leaky tank is gone.

What are the Disadvantages of a Combination Boiler?

Every technology has disadvantages, and the combination boiler is no exception. As I mentioned above, these systems are ideal for small homes and apartments, but larger homes run into a problem when higher demands are placed on the system. Without a tank to store water, these units can only accommodate small heating requests. If one user is taking a shower or washing dishes, the simple act of turning on the faucet in another room can cause water pressure rates to decrease, resulting in a change at the tap.

So, when thinking about which way to heat either your home or water, consider what it is you want to accomplish. If your home is small and has few users, an energy-efficient combination boiler may be just right for you. The system will provide you with on-demand heat, in a compact space, and your family may even save a few dollars in the process.