Guide to Gas Boiler Prices & Costs

A gas boiler is similar to a gas furnace in that it is a system that uses natural gas -- like propane -- to heat your home. However, a furnace provides heat by using air, while a boiler uses water. This water can be sent through pipes to provide heat to fan coil units to provide warm air, but it can also be used for heating swimming pools, baseboard heaters, radiant floor heaters, snowmelt systems, or even as steam to radiators. Learn more about what’s involved in the cost of purchasing and installing a gas boiler.

On This Page:

1. Average Gas Boiler Prices
• Westinghouse
• Weil-McLain
• Slant-Fin
• Triangle Tube
2. Boiler Installation
3. Additional Costs and Considerations
4. What Is a Gas Boiler?
5. Gas Boiler Terminology

Average Gas Boiler Prices

Gas boilers cost about $4,499 with most homeowners spending between $2,352 and $6,958. The price depends on the efficiency and brand. There are two efficiency styles: standard and high-efficiency. A standard model has an efficiency rating of 80 to 85 percent, which you might see listed as AFUE80 or AFUE85 (AFUE stands for Annual Fuel Utilization Efficiency).  A high-efficiency model will have an AFUE of 90 percent or more. This represents how much of the system’s energy is being converted heat under real-world conditions. For example, a 100,000 BTU system with an AFUE80 rating is losing 20 percent of its energy and producing 80,000 BTUs of heat. (BTU stands for British Thermal Unit, the amount of energy it takes to heat or cool one pound of water by one degree Fahrenheit.)

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Major Brands

Many companies that produce complete HVAC systems also produce boilers of various types. Here are four of the top manufacturers of gas boilers for residential use, along with information about popular models and their costs:

Westinghouse

All Westinghouse boilers are wall-hung, “fire tube” gas boilers. This means that hot gasses are used to heat a tube surrounded by water. Historically, this is the type of boiler used for steam locomotives. Today, however, it is generally regarded as the most efficient way to heat water for a residential boiler. Westinghouse offers seven models that range from 93 to 96 percent AFUE.

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Weil-McLain

Weil-McLain has been around since 1881 and offers an impressive selection of 44 different models of gas boilers for residential and commercial use.

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Slant-Fin

Slant-Fin offers a wide range of residential and commercial boilers. Each of their models strives to have as low a profile as possible to fit into small spaces. Here are a few of their most common residential models:

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Triangle Tube

Triangle Tube produces the wall-mounted Prestige Trimax Solo series and the Challenger Solo series, two of their most popular lines. Most of their residential models are wall-mounted.

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A Note on Wall-Mounted Boilers

Why would anyone want his or her boiler hanging on the wall for everyone to see? The answer is simple — space and convenience. Many wall-mounted boilers are only about six inches thick. This means that even if you decide to hide it in your hall closet, it’s not going to take up much room. Having it up in the living area of your house (many people install them in the kitchen or laundry room) makes it easier to access for routine maintenance.

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Boiler Installation

Because installation involves tapping into city gas lines, the DIY approach is not recommended. In fact, some municipalities require that installation be completed by a licensed contractor. Check your local codes before going with anything other than installation by a licensed professional.

Know What Kind of Boiler You Need

If you are replacing an old boiler, this part is easy. You should be able to get one of the same size and capacity as your old one. However, if you have made upgrades or additions to your home since your old boiler was installed, you may need more capacity.

Determining the BTU output you need can be done on your own to a certain degree. The base rule of thumb is as follows:

• If your house is in a warm climate, you need 30 to 35 BTUs per square foot.
• If your house is in a cold climate, you need 50 to 60 BTUs per square foot.
• If you have an older house, use the higher of the two numbers.
• If you have a newer house, use the lower of the two numbers.

This simple calculation does not, however, take into account things like:

• Quality of your insulation
• Sealing of your windows and ducting
• Whether your house is in the shade or in full sun
• How many people are in your house
• How often the exterior doors are opened and closed
• Other related variables

A professional can determine your required BTU output using what’s called a Manual J calculation. Some areas require a Manual J calculation before issuing permits, and some installers will include it in their estimate, while others may do it for free. A Manual J calculation typically costs around $100.

Compatibility With Your Existing System

Be sure to note the size of the lines going into and coming out of your existing boiler. When shopping for a new boiler, it is essential that you get one that will fit those existing lines. If the gas lines coming into your house are half-inch, for instance, you should get a boiler that will fit half-inch lines. Adapters are not permitted in all areas and are common failure points on many appliances, so they are best avoided.

Average Cost to Install

The average cost to install a boiler depends on a few factors. Obviously, if you are buying a more expensive boiler, that will be the biggest cost. In addition, you should expect to spend the following on the installation of your new gas boiler:

• Standard boiler (AFUE 80 percent to 85 percent) — $2,500 to $5,000
• High Efficiency boiler (AFUE 90 percent to 99 percent) — $6,000 to $9,000

If you are replacing an oil-fired boiler with a gas boiler, these costs can increase by as much as $2,000.

Location

Depending on the complexity of the job, a basic residential installation can take one or two days, during which time you should plan to be without heat. Replacing an old boiler in your attic or basement could take longer and cost more because of the location of the unit and the difficulty getting it out and putting the new one in.

Your estimate should include removing and disposing of your old boiler. It should also include all required wiring, piping, fittings and other things needed for the boiler to function. In addition, there may be extra costs that are not included in the installation cost.

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Additional Costs and Considerations

Permits

Your boiler installation might require permits. The cost of these permits can vary from place to place, and the price range is quite wide. Be sure to check with your local government to see if permits are needed. They usually cost between $50 and $300.

Ductwork

Installing the most fuel-efficient boiler ever made won’t mean much if your ductwork leaks. An inspection of your ductwork is often part of boiler installation, but even if it’s not included, it is a worthwhile investment. A properly hung and sealed ducting system will lose 2 to 5 percent of its energy, but an improperly hung system or one with leaks can lose a costly 50 percent or more.

Ductwork can develop leaks due to expansion and contraction through cycles of heat and cold. Replacing ductwork costs an average of $35 to $55 per linear foot, including parts and labor. A typical single-family home can cost anywhere from $1,000 to $5,000 for entirely new ductwork. (Older ductwork may cost even more if asbestos removal is involved.)

Removal of Old Tank

If you are converting from an oil-fired boiler to a gas boiler, removing the old oil tank will be an extra cost. If your old oil tank is in the basement, you can expect to pay an extra $390 to $880 to have it removed. Many of these old tanks still have oil in them and are very heavy.

If you have an underground oil tank, you have a potential environmental and safety hazard on your hands. Old oil tanks can corrode and leak into the soil and groundwater, or can collapse from above and cause a serious danger to anyone who may fall in. You will be held liable for both. Having an old underground tank removed can cost from $1,500 to $3,000 or more, depending on the size of the tank.

Rebates and Tax Credits

Upgrading your old boiler to a newer, high-efficiency model may come with financial incentives toward the purchase price and/or your taxes. The amount of rebate you can get varies from state to state, but total incentives can run from $100 to $2,000 depending on where you live and what kind of boiler you install. Federal tax credits are usually handled through Energy Star, which routinely offers a 30 percent credit. Not all Energy Star appliances qualify for the rebate, and some may only be in your primary residence as opposed to second homes or rentals, but it’s worth looking into to get a third of your installation cost credited.

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What Is a Gas Boiler?

Some people use the term “boiler” when referring to a water heater. This is incorrect, as a water heater does not boil water. Its purpose is to heat water so that when you turn on the hot tap, you get hot water. If it were boiled off into steam, not only would it be a big risk for burn injuries, it would also defeat the purpose of a water heater. A gas boiler doesn’t boil water unless there is a steam system, such as a radiator. Then, certain lines boil the water into steam and pump it to where it’s needed.

How Do Gas Boilers Work?

The main components of a gas boiler are:

• A water source
• A gas supply
• A pilot light
• Burners
• Heat exchangers
• A pump

The water enters the system, usually from your community’s water supply. Natural gas also comes in from the street. The pilot light ignites the burners, which heat up the water as it passes through the heat exchangers. A pump then sends the hot water (or steam, if the system calls for it) where it’s needed.

Some boilers have a water storage tank. This allows a certain amount of hot water to be available on demand. These are often used in apartment complexes and large homes. However, some places might be too small to accommodate a water storage tank, and instead heat the water when it comes into the house on an as-needed basis. You’ll usually find these in very small places where space is precious.

Increasing Popularity

The idea of a boiler in a house used to conjure up images of a rusted iron behemoth wheezing away in your great-grandmother’s basement. In fact, many of these old boilers are still around and fully functional. They fell out of popularity when the industry switched to steel construction, which was cheaper and less labor intensive. Steel, however, proved not to be quite up to the task. The steel boilers had more localized pitting and corrosion than their wrought iron counterparts, which had been around significantly longer. More homes switched to direct gas or electric heating. Eventually, the boiler became identified with either heavy-duty industrial use or seen as a relic of the old days.

Today, gas boilers have benefitted from advances in technology and increased interest in natural gas. Though they still produce a degree of waste that must be sent out through exhaust vents, advances in cleaner-burning natural gas have made gas boilers very popular in Europe, particularly condensing boilers, which trap a certain amount of escaping hot gases for reuse in heating water. The savings from increased efficiency is making them increasingly popular in the northern parts of the United States as well, and advances in materials are making them more resistant to corrosion, leading to lower maintenance costs.

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Gas Boiler Terms to Knows

AFUE

Sometimes pronounced “a few”, AFUE stands for Annual Fuel Utilization Efficiency. This rating measures the fuel efficiency of heating devices such as boilers, furnaces and water heaters. It is a more reliable way to measure your system’s efficiency than the industry’s EER (Energy Efficiency Ratio), which is used in testing environments and rates how well a system is expected to operate in optimal conditions.

AFUE is based on the seasonal average efficiency, including operating transients such as momentary variations in the electrical current. It is the more accurate rating to base a purchase decision on. A boiler with an EER of 72 percent may have an AFUE of only 64 percent. EER is good for measuring an instantaneous fuel consumption rate, but the AFUE is more relevant to actual operating efficiency.

BTU

A BTU represents the amount of energy it takes to heal or cool one pound of water by one degree Fahrenheit. For a physical example, one four-inch wooden kitchen match, if lit and consumed entirely, produces one BTU. It’s usually listed as BTUH or BTU/h for “British Thermal Units per hour.” “MBH” is a common abbreviation for “thousands of BTUs per hour.” So a boiler listed at 85MBH produces 85,000 BTUs of energy per hour. (Remember that the AFUE tells you what percentage of those BTUs is actually coming out as heat.)

Energy Star

You’ve seen this logo on many appliances, but you probably haven’t given much thought to what it means. Far from merely being an industrial pat on the back, an Energy Star rating can save you money and should be among your top requirements when purchasing a boiler.

Energy Star is a standard for energy efficiency that was created by the Environmental Protection Agency and the Department of Energy in the United States in 1992. It has since been adopted internationally. An appliance with the Energy Star logo has been tested both in the lab and via samples purchased off of store shelves to ensure that it is using at least 10 to 30 percent less energy than federal standards prescribe.

Gas boilers are increasing in popularity due to advances in technology and materials. Thanks to improved styles and design techniques, the modern gas boiler is an energy-efficient and stylish way to heat your home and water supply.

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