Boilers are an energy efficient and environmentally friendly mode of heating. They work by cycling cold water through a series of heated pipes before distributing it throughout your home as either hot water or steam.

Determining the cost of installing a boiler is complex and can be tough for homeowners to figure out. There are also plenty of factors you’ll need to consider before installation. Before you start, read up on the repair and replacement costs and additional related information.

On This Page:

1. Boiler Costs by Type
• Combination
• System
• Standard
• Differences between Water Heaters & Boilers
2. Boiler Replacement Costs
3. Boiler Replacement Considerations
4. Ratings
5. Sizes
6. Permits

Boiler Costs by Type

If you have a boiler installed or replaced, you might pay anywhere between $3,323 and $7,270. On average, homeowners tend to pay $5,259.  These prices are highly dependent on the type of boiler you choose. There are several styles on the market. High-efficiency models help you save on energy bills in the long run, but they have a higher initial investment. Sealed combustion boilers draw air from the outdoors for combustion instead of indoor air. This eliminates back-drafting, which can release potentially toxic amounts of carbon monoxide into your home. There are gas models and oil models to consider as well.

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Combination Boiler

The combination boiler, or Combi, is very popular in small residences like apartments or studios. A Combi doesn’t include a storage tank, as it receives water from the water mains. A small tank can be added, however, and many homeowners who have the space pursue this customization. This is called a Combi-storage boiler.

Combi boilers provide hot water and heat on demand with no wait time. They work best with low-occupancy residences, such as a home with a couple and one small child. Using multiple taps at once can cause a drop in water pressure. The average price for a combination boiler is $1,300.

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System Boiler

System boilers are also called sealed-system boilers. They maintain water pressure to ensure fast delivery and to allow simultaneous use of multiple taps. They store water in a cylinder, where they heat the water before sending it out to taps or to be converted into steam for heaters.

Sealed-system boilers work well in most average-sized homes. Since they keep the water pressurized, there is very little drop in water pressure when multiple taps are opened at once. They deliver heat quickly but not instantly, so there is a brief waiting period. If the cylinder runs out of hot water, the wait time increases slightly as fresh water heats up again. The average cost for a system boiler is $1,500.

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Standard Boiler

Standard boilers are also known as conventional boilers. They heat water rapidly in the pipes that run through the tank and send hot water out to taps as necessary. Larger homes and buildings most often use standard models. These units are also popular for floor heating systems and other larger scale tasks. The average cost for a standard boiler is $3,500.

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Comparing Water Heaters & Boilers

A boiler and a water heater, while similar in function, are not identical. Essentially, a water heater is a storage tank with heated tubes that keep the water at a certain temperature. When hot water is needed, the unit siphons hot water from the top of the heater. It then replenishes its supply by heating cold water and moving the freshly heated water to the top.

A boiler can deliver hot water, but it can also boil water to deliver steam. This is a particularly effective way to move heat for two reasons:

• Steam is denser than air and can hold more heat than air alone.
• Steam is lighter than water and takes less energy to move.

Boilers are more energy-efficient, but they also save money in another way. By using a boiler instead of a water heater, you can dispense with a traditional furnace, since you’ll have one device that can do the job of two.

Fuel Type: Boilers are also differentiated by their fuel type. Most run on natural gas or liquid propane. Oil-fired models are also common.  Boilers can also be fueled by wood, electricity or geothermal energy. Of all of the options, wood pellet burning is gaining popularity as the exhaust is cleaner and fewer particulates are vented. The cost of these alternative fuel systems varies widely, but it averages around $2,300.

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Boiler Replacement Costs

Most boiler issues come down to weighing the costs and benefits of repair versus replacement. epairs typically cost between $300 and $500, which can involve replacing key elements like heat exchangers, burners, chimneys or lines. Over time, the mix of water and fuel can have an effect on the boiler’s components, possibly inducing corrosion.

The cost for replacing a standard gas boiler is about $4,000. A high-efficiency model costs about $7,500. This cost estimate usually includes removal and disposal of the old unit, as well as all necessary lines, ducts and wiring needed for the new system to run properly.

Replacing an oil-fired boiler is typically a bit more expensive. The oil tank itself occasionally needs replacing, and other factors can add significantly to the project cost. Potential costs include:

• The cost for replacing the boiler itself averages $7,000.
• The tank must be tested for leaks or other problems. This costs about $500. If the tank needs to be replaced as well, that can add another $1,000 to $2,000 to the cost if it’s above ground. The cost is closer to $3,000 or more if the tank is below ground.
• Before a tank can be replaced, however, the soil must be tested to see if the tank had leaked. This can cost another $300 to $500.
• If a cleanup is necessary, the average cost ranges from $2,500 to $10,000 for minor environmental cleanup. The average cost for this is $3,500 to $4,600.
• Major ground contamination can cost from $15,000 to $100,000 or more depending on the extent of the damage.

New tanks are made of corrosion resistant materials and usually have an expected lifespan of about 30 years. Removing and replacing an oil tank requires permits, which your local fire department usually issues  Be sure to document this process thoroughly with notes and photographs. Since the tank is installed underground, there’s no other way to verify information about the unit or its installation without digging it back up again.

Changing Boiler Types

Gas boilers are the most efficient style on the market. With this information in mind, you might decide to change your oil-fired model over to a gas-fueled unit. Replacing the old and swapping in the new is no easy task, though. There are several costs to consider before you go this route.

• Gas-fired equipment costs less than oil-fired equipment. In some cases, the difference is as much as $5,000.
• Oil has to be delivered to your house by truck. Gas is piped in directly from the city.
• If you don’t already have a gas hookup, your local utility company will have to install one. This involves digging a trench and running the line to your house and installing a meter. The average cost for this is $1,000 to $1,500, though your utility company may offer a discount to win you over as a customer.
• A contractor will have to hook up the gas lines between the meter and your house. This normally costs around $500 to $1,000.
• Your chimney will most likely need a new liner to accommodate the gas boiler exhaust. This can cost between $750 and $2,000.
• The cost of removing an old oil tank depends on where it’s located. If it’s in your basement, removal can cost from $500 to $1,500. If the tank is buried in your yard, the excavation and removal can cost from $1,500 to $3,000. You can decommission a tank by contracting a service to drain the oil and fill it with an inert substance, but the cost of this varies quite a bit and depends on numerous environmental factors.

While it seems like a lot of money to switch from oil to gas, it should be noted that oil heating could cost as much as double the price of gas heating. Oil is a particularly volatile commodity, and the price can skyrocket or plunge based on global events and instability. For environmentally conscious homeowners, gas boilers have a lower carbon footprint than oil-fired units.

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Boiler Replacement Considerations

If you're replacing an old heating system with a new boiler, then the cost to install might increase. One reason is that you might have to install a chimney liner. The liners for gas models are cheaper than those for oil models, so make sure to figure that into the cost of your replacement budget. You'll also need to consider the cost of removing your old system when you calculate your budget.

Replace or Repair?

Boilers, like everything else, don’t last forever. With good maintenance and care, they can last a very long time. There are gas units still humming after 40 years and a coal-fired steam boiler still functioning after 134 years.

The typical boiler has a life expectancy of 15 years. Has yours been thriving for 20 years? As long as it’s still functioning at comfortable temperatures, you may want to ask yourself whether or not it even needs replacing or other drastic action.

How often has it needed repairs?

If this is your first repair, your boiler may not need replacing just yet. Compare the cost of the repair to the cost of replacing. A repair averages between $300 and $500 for most common issues. A replacement can cost between $3,000 and $5,000 for the new equipment installation, inspections and removing the old system. During installation, you’ll be without heat for a couple of days or even a week if complications arise.

Has it been working fine otherwise?

If your boiler has been providing comfort at appropriate levels and you’ve been maintaining your home’s insulation and seals at doors and windows, then there’s probably no need to replace it. If you have made additions to your house that have increased the floor space, your old boiler may not do the job anymore. There’s most likely nothing wrong with the unit, it just might not be powerful enough to meet the new load that your home requires.

Have you been inspecting it?

A yearly inspection is recommended by most professionals in the industry, and that’s not just so they can have repeat business. A crack in the boiler’s heat exchanger can allow poisonous gases to leak into your home. If you haven’t had it inspected, you should do so immediately. If multiple issues are found during an inspection, you should think about replacing your system if it’s out of warranty.

Replacing your boiler can be an expensive prospect, depending on your location and the extent of the job. Before you begin, be sure you understand all of the factors involved, as well as the options available for new boilers. New technology and materials help ensure that your new system will provide comfort, efficiency and plenty of cost savings for years to come.

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Boiler Ratings

Each boiler unit comes with an AFUE (annual fuel utilization efficiency) rating. The higher the rating, the more efficient a boiler will be. The models that are the most energy efficient tend to have the highest upfront cost attached. Models with a rating of 90 or higher will reduce home heating costs by 30 percent or more overnight when replacing an older unit.

Thermal Efficiency

Thermal efficiency is a rating based on the unit’s operation under ideal conditions. It is often higher than the AFUE rating because all variables are minimized. This gives the manufacturer and testing agency an idea of how much energy is expended and produced from input to output.

AFUE

AFUE is the rating that consumers need to know. It reveals how much energy is actually being converted into useable heat during real-world conditions. While thermal efficiency focuses on ideal conditions, AFUE tells you how well it can be expected to perform against temperature swings, extremes, sudden cold snaps, energy surges and other variables. A boiler may have a thermal efficiency rating of 78 percent, but may have an AFUE rating of 64 percent when faced with real-world test conditions.

High efficiency units have an AFUE of 90 percent or higher. These are increasingly becoming available only as condensing boilers. They trap much of that heat waste and use it to preheat the water, which ensures that the system runs on less energy. A condensing model often loses only about 2 to 3 percent of its heat when all is said and done. However, the trapped heat doesn’t count towards the AFUE.

Factors That Affect AFUE

Sometimes your boiler doesn’t provide enough heat. Though it may be properly sized for your home, but the temperature remains chilly. Before blaming your boiler, check the following:

• Insulation: poor or damaged insulation can cause your home to lose heat through its walls and ceilings.
• Windows and doors: windows and doors that don’t close properly or that have lost their seals can cause heated air to leak out. Warm air will always rush towards cooler air, so if you encounter this situation, you’ll lose a significant amount of heat through these leaks.
• Ductwork: as ductwork goes through warm and cool temperatures, it expands and contracts. This can cause weakness and erosion at the joints. Improperly hung ductwork can restrict airflow, and ductwork without insulation can cause a great deal of heat loss. This can amount to anywhere from 10 to 50 percent or higher in wasted energy.

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Boiler Sizes

It's important to install the right size boiler for your home. If your unit is too big or small, then you won't reap the energy savings benefits, regardless of the AFUE rating. To determine what size boiler you need, you should be aware of two calculations. One is a simple guideline that will give you a ballpark idea of what size you need. The second is an extended calculation that will tell you almost precisely what size you need. Most homeowners use the simple calculation because the other one can take two hours or more.

Simple Calculation

To figure out the simple calculation, first confirm the square footage of your home. If you don’t know it, multiply the length and width of each room and then add those results together. Then multiply that result by the following based on your average climate:

• Warm:30 to 35
• Cold: 50 to 60

If you live in a house that’s 20 years or older, use the higher number. If you live in a newer house, use the lower number. The result tells you roughly what size boiler to get. This is an imperfect way to calculate your AFUE, but it will keep you from buying a 125,000 BTU boiler when all you need is a 75,000 BTU one.

Manual J Calculation

This is the calculation that a professional wills. A contractor may include it in his or her estimate, but you can also have it done independently for around $100. This calculation takes into account the following:

• Foundation type
• Roof type
• Roof color
• Insulation values
• Windows
• Exterior doors
• Desired interior temperature
• House location
• House size
• Direction the house faces
• Construction materials used to build the house
• Landscaping that affects how much sun or wind hits the house

There is nothing to stop you from doing a Manual J calculation yourself, and there are many places that will provide online calculators for free. Most homeowners are content to leave it to a professional who may spot minor problems that will affect the calculation, such as an inability to put ductwork in an ideal spot to most efficiently heat a room.

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Permits

Many locations require permits to replace your heating system. Talk to your local pro to learn more about local regulations, and make sure to check with your local municipality as well. Permits are not prohibitively expensive.  Depending on where you live they cost between $50 and $300.

Some local governments also require a fire inspection before heating system replacements. The fees for these are dependent on the size of the boiler and tend to run between $40 and $75.

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