Boiler vs. Furnace – Which Is More Energy Efficient?

Presidential Heating & Air Conditioning

Gaithersburg HVAC Contractors


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Is a Boiler or a Furnace Better for Your Home?

an HVAC contractor located in Gaithersburg, MD who is working on a boiler repair for a homeowner whose house is experiencing heating issuesBoilers and furnaces as heating systems each have their advantages and disadvantages. With the range of choices available in each type of system, a homeowner should understand what each can offer in terms of performance and energy efficiency before choosing between a boiler an a furnace installation.

Boiler Installation

A boiler is a closed tank that heats water or other liquid under pressure. Similar to a pressure cooker, the boiler creates pressure just by the fact that the tank is completely closed. The pressure helps the system pump out the heat and drive up temperatures.
In the simplest terms, the boiler heats the water using a fuel source, such as natural gas, oil, or electricity. The boiler uses a burner to burn the fuel, which creates hot gases. These hot gases are transmitted through a heat exchanger where the heat is used to heat the water in the boiler.

After heating the water, the boiler system vents the combustion gases out of the house using a venting system. For obvious safety reasons, the venting system must be properly designed, installed, and maintained to prevent fire hazards and carbon monoxide build-up.

The hot water from the boiler is used to heat the home, by steam or by hydronic heat.

Steam. With steam heat, the boiler heats the water until it boils, creating hot steam. Steam, being lighter than air, rises through a piping system without any mechanical assistance to the highest point in the system, usually a radiator. Through the radiator, the steam radiates its heat into the air and condenses back to water. This water, which is heavier than the steam, falls through the piping system back to the boiler, where it is re-heated and the process begins all over again.

Hydroponic. A hydroponic boiler system heats water to a selected temperature below its boiling point and sends the hot water (not the steam) to hydronic radiators in the home. Because hot water will only rise very slowly, the hydroponic system requires a pump to circulate the water from the boiler through the piping to the radiators. After the hot water transfers its heat out into the air, the water returns to the boiler to be heated again.

Boiler Efficiency in the Home

a boiler room in a large home in Maryland that will be removed since the homeowners are looking to receive a two-stage furnace installation for the upcoming winterBy far, gas boilers are the most common form of home heating boilers. They are usually cheaper to install and operate than oil boilers. Oil-fueled boilers require an oil storage tank. The oil must be delivered to the home and stored in the tank until it’s needed. Though oil boilers are not as eco-friendly as gas-fueled boilers, some models can be more efficient than some gas boilers. In general, however, oil boilers are more expensive to operate than gas boilers.

Electric boilers are often used in homes where natural gas is not available. Electric boilers burn cleaner than the others, but electric boilers are not as efficient and are more expensive to operate.

Furnace Installation

A modern home furnace is powered by electricity, gas, or propane. A simple, single-stage furnace works when the valve supplying the burner with fuel is opened. Once the valve is opened, the fuel travels to the burner where it is ignited by the furnace’s pilot light. The burner heats the heat exchanger, which in turn heats the air for your home. A blower assembly pushes the heated air through the ductwork of your home to provide the heat. The blower also draws fresh air through the furnace and back through the system for reheating.

A two-stage furnace allows the furnace to operate with the valve in a partially opened position. The furnace’s control board and thermostat control the valve position. When the weather gets very cold, the furnace can operate with the valve fully opened and operate at full capacity.

Furnace Efficiency in the Home

Gas furnaces are usually the most efficient furnaces in terms of both performance and furnace installation, with some models operating with an efficiency rating of 95 percent. This means that only five percent of the energy is not used to provide heated air to your home. An electric furnace is less expensive to buy, but costs more to operate than a gas or oil furnace.

a Gaithersburg, MD HVAC contractor giving a thumbs up to a homeowner after he just performed a complete furnace installation so the home can be kept warm during the winterWhether you should buy a single-stage or two-stage furnace also depends on your budget. You will spend more to buy a two-stage furnace installation than a single-stage furnace installation. However, the extra expense is likely worth it because the two-stage furnace burns less fuel than a single stage furnace, which means it is less expensive to operate during the winter season. For example, in the milder part of winter, the two-stage furnace operates with only 60 percent of the fuel a single-stage would use. It operates at full capacity only when necessary to keep your home comfortable during the coldest days.

A two-stage furnace also provides more even heating throughout your home. A single-stage furnace runs only at full blast, so it heats your house rapidly and then turns off. The inside temperature can cool before the heated air is adequately distributed leading to uneven heating.

Considerations in Choosing Between a Boiler or Furnace

With a basic understanding of how these heating systems work, here are some key factors to consider when deciding whether a boiler installation or a furnace installation is better for you:

Boiler Advantages and Disadvantages

  • Some boiler systems can do double-duty to provide hot water. Some boilers can heat your house and provide you with hot water throughout the year.
  • Boilers require no ductwork, and some models can also provide radiant floor heating.
  • Boilers maintain higher humidity levels.
  • Boilers are much more expensive to buy, but hold up longer than furnaces.

Furnace Advantages and Disadvantages

  • A new furnace can use your home’s existing ductwork.
  • Ductwork can be used by your furnace and your air conditioning.
  • Furnaces cost less to buy than a boiler.

In summary, if you already have ductwork in your home and cost is an issue, you will likely be better off with a furnace. However, if you are building a new home or already have boiler pipes installed, a boiler may be the best choice.

Consult with a Reputable HVAC Technician

Before you make a final decision, contact a professional HVAC contractor. An experienced heating technician has the background and expertise to evaluate your needs and select the right system for your home.

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