How Much Does an Gas Furnace Cost to Install?

Buying a New Gas Furnace

When buying a new replacement furnace unit it is important to know what you are looking for so you can make the best decision for your HVAC system purchase. Here are a few things that you will want to keep in mind to make sure you are getting the best return on your investment:

• Should you repair or replace your broken furnace?
• Which gas furnace brand is best?
• What size gas furnace do you need?
• What energy efficiency level do you need?

Furnace Replacement vs Repair

The basic rule of thumb for any gas furnace replacement when deciding if you should invest in a costly repair or replace your unit altogether is this. If the cost of repairing your gas furnace system is more than half of its current value, it would be more cost effective to get a new gas furnace installed. You may hear your HVAC contractor refer to this as the “$5,000 rule of thumb” – which is the average amount you can expect to pay for the cost of HVAC replacement.

For example, you can multiply the costs of your HVAC repair by the current age of your gas furnace to determine if the repair is worth the investment. If your current gas furnace is 10 years old and your repairs are estimated at $480, it would put you at $4,800. It will probably be better to do a full replacement in that situation as the cost to repair is almost at the $5,000 rule of thumb.

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What Factors Affect Gas Furnace Installation Costs?

When you are installing a new gas furnace, the total cost estimate for installation is pretty simple to break down into line items. You will pay for the new gas furnace unit, a local service charge or labor cost, and the disposal of your old furnace, equipment, and any local permits required. You may also need ductwork replacement to make sure your new gas furnace is working properly.

• A furnace unit’s price will make up about 60% of your installation cost estimate
• The local labor costs will usually be around 25% of total costs to install
• The additional costs such as old furnace removal, extra equipment, and local permits needed make up around 15% of your installation costs

If you also need ductwork replacement you can expect that to cost an additional $300 to $585 per duct run replaced.

Cost to Repair a Gas Furnace

When deciding to install a new gas furnace you will need to decide if it is best to repair your broken furnace or to replace it completely. The average price for a gas furnace repair is around $325. It depends what exactly is wrong with your furnace, but it may be more cost effective to completely replace it if your current unit is older.

Here are a few things to check that could mean your furnace just needs a simple repair and will not require a full replacement:

• Check your circuit breaker box – sometimes power outages can cause your circuit breaker to shut off energy sources to your furnace or there could be issues with your fuses.
• Check your furnaces air flow – if you are getting low air flow it could be a simple issue with your furnace filter. If your gas furnace filter is clogged it could impact airflow quite a bit.
• Check your thermostat – your furnace’s thermostat could be malfunctioning or low on battery level. Check for faulty wires around your thermostat as well.

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Furnace Costs by Brands

Choosing a top gas furnace brand is an important factor in the quality of your furnace and also what kind of installation costs you will incur as well as warranties offered. Here is a list of some of the best gas furnace brands on the market:

What Size Gas Furnace Do I Need?

When trying to decide on what size furnace unit you need, it is best to get one with adequate heating output also known as BTUs. You will want a new gas furnace that at a minimum can provide 40 BTUs of heat per sq. ft of home area needing to be heated if you lived in a moderate climate Zone 3 area. For a 2,400 square foot home you will want to install a new furnace with at least 96,000 BTUs heating output capacity. Use our climate heat map below to decide the best BTU output for a replacement furnace in your area.

What Size Furnace Do I Need?

Use our quick and easy Furnace Size Calculator tool to determine what size furnace you need for your home and climate

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What AFUE Rating Do I Need?

Most homes need at least an 80% AFUE rating. You can install a new furnace with an AFUE rating from as low as 78% to a high of 97%. This will depend on what kind of heat output – BTUs you need based on your local climate. See our climate zone map below.

Gas furnaces are the most popular home heating choice and fairly affordable in most cases. However, in the long run your energy bills will add up and it is always smart to opt for an energy efficient gas furnace from the get go. You will want to make sure you are getting a unit with a great AFUE rating (annual fuel utilization efficiency.) A new gas furnace’s price will rise with higher AFUE ratings, but that investment will help save you money longterm.

How Does a Gas Furnace Work?

As the temperature in your home drops below the thermostat temperature setting, the furnace system activates to raise the inside temperature. Once activated, fuel and air combine in the burner where an electronic igniter or pilot light ignites them. The hot gases rise up through the heat exchanger to heat your home’s air. Gases and exhaust fumes are diverted to the home’s exterior via a furnace flue, or pipe, often through an exterior wall or through the roof. Gas furnaces are the heating unit of an HVAC system and are usually paired with a central air conditioner unit installation.

Larger furnaces might incorporate two burner systems to heat larger volumes of air. This would be typical in homes over 2000 square feet or in some commercial buildings. The furnace continues to fire until your home’s temperature rises to the programmed settings on the thermostat after which it will shut down. When the temperature drops below the thermostat settings again, the furnace system is reactivated and starts the whole process over again.

Gas Furnace Blowers

Air circulation is achieved by means of an electric fan referred to as the blower assembly. Its job is to draw fresh air into the system and distribute warm, conditioned air throughout the home. A return vent – a large, flat vent located in the ceiling, wall or floor – is the point where the fresh air enters the furnace system and is usually located close by.

The heated air is distributed through a series of air ducts and vents connected to the plenum attached to the furnace that channel the heated air to specific areas within your home. The plenum acts as a junction point for both the gas furnace and its adjoining ductwork. Often a square box, it attaches to the furnace on one end, while the ductwork circuit connects to one or several of the remaining five sides of the square. The plenum is commonly fabricated out of galvanized sheet metal, or fiberglass duct board.

Gas Furnace Humidifiers

Some furnace systems incorporate a humidifier, located close to the appliance to mitigate the drying of heated air, which can cause respiratory discomfort. A simple way to look at it is as the air is heated, moisture within the air dissipates. The humidifier replenishes the air’s moisture content that is lost during the heating process to enhance the overall comfort levels within the home. Most humidifiers incorporated into a gas furnace system are connected directly to a water line, which will supply a continuous flow of water to the device. The humidifier should also include a drainpipe to channel any condensation that accumulates during the process to your home’s exterior. Older humidifiers might require that you fill them with water as needed and empty a condensation tray manually.

Hiring a Gas Furnace Installer

Due to their ever-advancing technologies; it is easy to get lost in translation when receiving price quotes from gas furnace installers. Asking a furnace installation contractor the right questions is key to purchasing the correct furnace for your home and a quality installation.

• Ask for several bids from local furnace contractors. Be careful to not always go with the lowest bid, as you could potentially get inferior service and equipment.
• Ask the contractors what their equipment markup is. A cheaper labor price might include hidden markups in the equipment.
• Ask your furnace contractor to install a new thermostat. Newer technologies require newer devices to run them.
• Ask for a detailed estimate or proposal that outlines the entire scope of the furnace installation job including equipment manufacturers with model numbers and scheduled completion dates.
• Ask the contractor to go over your new furnace cost estimate including mathematical calculations used to size the natural gas furnace. Verify that their calculations are correct to avoid buying an undersized or oversized gas furnace.
• Ask for name brand equipment. Cheap knockoffs might fail and leave you out in the cold.

A lot goes into replacing a gas furnace such as selecting the right equipment and choosing the right contractor for the job. Being thorough and doing your homework will increase the chances of a smooth furnace installation or repair. Use this step by step HVAC contractor checklist during your HVAC installation to make things easier on you and also the installer.

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Gas Furnace Maintenance Tips

To maintain your gas furnace system and reduce the likelihood of costly repairs in the future, it is recommended that you schedule annual maintenance and cleanings with a certified heating and air contractor. This should be done before the winter season sets in, when HVAC contractors are likely to become busy. This will give you peace of mind and assurance that your system is running at peak efficiency when the cold weather hits.

Cleaning Gas Furnace Filters

As the fresh air enters the furnace system, it must pass through a filter to remove dirt, dust, dander and other contaminates that could harm the system. The filter is often located within the return vent but sometimes fitted directly to the furnace assembly itself.

It is important to clean or replace the filter on a regular basis to maintain peak system efficiency. A dirty filter reduces airflow causing your system to work harder to circulate the air. This puts unneeded stress on its components and leads to higher energy consumption, which translates into higher energy costs for you. A stressed or overworked furnace system is also prone to mechanical failures and malfunctions leading to costly repairs.

Average Furnace Warranties

Natural gas furnaces usually have two types of warranty coverages. One warranty covers the heat exchanger and the other covers the main components. Heat exchangers usually have a a lifetime limited warranty or a  20 year limited warranty. The main component warranty you usually see includes coverage on the blower’s motor, furnace igniters, and on all controllers, as well as any other main parts of your gas furnace.