Affiliate Disclosure: This Old House‘s Reviews Team is committed to delivering honest, objective, and independent reviews on home products and services. To support this business model, This Old House may be compensated if you purchase through links on our website.
Boilers convert energy from gas, oil, or electricity into heat to keep your home warm. Usually, a boiler heats a radiator system, but it may also function as a water heater for your appliances and fixtures. While boilers are sturdy pieces of machinery, they only last between 15–20 years. If you need to replace your old, worn-out boiler with a newer, more efficient model, use our cost guide to learn about the process and get an idea of how much you might spend.
A new boiler could cost anywhere from $4,290–$10,070, with the average cost to replace being $7,938.Get Free Estimates
In a survey conducted by Consumer Reports, homeowners paid an average of $391 for boiler repairs in 2021.Get Free Estimates
Fuel type typically has the greatest impact on boiler installation cost. Prices can range from $700-$6,000.Get Free Estimates
Boiler Replacement Cost
According to Consumer Reports, the average cost to replace a boiler is $7,938. Depending on the size and type of boiler you buy, you could pay anywhere from $4,290–$10,070, with the following factors affecting cost:
- Size: Boilers that can put out more heat cost more.
- Fuel type: Most boilers run on natural gas, propane, or heating oil, but some use electricity or wood.
- Brand: While most boilers fall within the same price range regardless of brand, some high-tech brands cost more.
- Installation: Different fuel types are associated with different installation needs. The more intensive the labor, the higher the cost.
- System type: The way boilers heat and store water makes some systems more complex than others, also affecting the cost of labor and installation.
Boiler Replacement Cost by Size
Boiler size is commonly measured in BTU, or British Thermal Units—the amount of heat energy the machine is capable of producing. The square footage of your home is one factor that determines how large of a boiler you need, but you also need to take your climate into account. To get a rough idea of what size boiler you need, multiply your home’s square footage by the following values:
- 20–30 for hot climates (Florida, Gulf states)
- 25–35 for warm climates (Southeast, coastal California)
- 30–45 for moderate climates (mid-Atlantic, lower Midwest)
- 45–55 for cold or mountain climates (Pacific Northwest, Rocky Mountain states)
- 50–60 for freezing climates (Northeast, upper Midwest)
If your home is newer, well-insulated, and energy-efficient, use a multiplier toward the low end of the range. If you have an older, poorly insulated home, choose the higher value. For example, a newer home of 2,000 square feet located in Virginia probably needs a boiler capable of producing 60,000 BTU. Here are some approximate prices for standard-efficiency gas boilers for homes located in moderate climates.
|Home Size (sq. ft.)||Boiler Capacity (BTU)||Price|
Boiler Replacement Cost by Fuel Type
Most boilers run on natural gas or propane, but some homes in the northeastern U.S. run by heating oil stored in an oil tank near the boiler. Less commonly, some boilers are powered by electricity. While electric boilers are very efficient, they’re also low-capacity and expensive to run, so they’re usually only found in warm climates or used as secondary heating for homes with another central heating system. Wood boilers are rare, but they can still be found in some rural areas. Here’s what you might expect to pay for a 90,000 BTU boiler based on fuel type.
Cost of Boiler Replacement by Brand
The most popular boiler manufacturers sell mostly to contractors rather than customers, so it’s difficult to obtain pricing information apart from installation. Here are some estimates from popular brands.
Boiler Replacement Cost of Installation
Fuel type typically has the greatest impact on boiler installation cost. Electric boilers tend to be the least expensive to install, while wood boilers are often the most expensive. HVAC professionals usually charge $75 to $125 an hour, but plumbers can also replace a boiler system if they have an HVAC license.
|Boiler Type||Installation Costs|
Boiler Replacement Cost by System Type
Aside from fuel type and brand, residential boilers can also be classified by the way they heat and store water. Depending on how they store water, boilers can be conventional, system, or combination (combi) boilers. They may use either hot water or steam to produce heat. Additionally, most high-efficiency models are condensing boilers as opposed to standard efficiency, non-condensing boilers.
We’ll further explain these distinctions below, but here’s how these classifications affect boiler prices. Keep in mind that a boiler can fit into more than one of these categories; for example, you can have a conventional, non-condensing steam boiler.
|Type of Boiler||Price|
Other Factors in Boiler Replacement Costs
Along with the price of the boiler itself and the cost of labor to install it, you may encounter a number of additional expenses during the process.
- Manual J inspection: Instead of approximating, HVAC professionals can calculate the exact BTU requirements to heat your home based on climate, insulation, types of doors and windows, and even the color of your roof. This is called a Manual J inspection, and it typically costs about $100.
- Switching fuel type: If your home is set up for one fuel type but your new boiler uses another, you’ll typically incur additional material and labor costs. The same applies if you want to change where the boiler is located in your home.
- Permits: In many areas, any type of HVAC installation requires a permit, which can cost anywhere from $50–$300.
- Insulation: During a Manual J inspection, the contractor may find that you can use a smaller boiler if you upgrade your home’s insulation. A better insulated home is more energy efficient and thus costs less to heat.
- Repair: If you don’t have to replace your boiler, it’s nearly always cheaper to repair it. According to a survey by Consumer Reports, homeowners paid an average of $391 for boiler repair in 2021.
Types of Boilers
You’ll generally see the most variety in natural gas boilers, since these are the most popular models. They may fall into one or more of the following categories.
Conventional, System, and Combination Boilers
Conventional or standard boilers are large and time-consuming to install, but they’re the best type for larger homes. Standard boilers have a boiler unit and two tanks: one for hot water and one for cold water yet to be heated. On the other hand, system boilers have only a boiler unit and one hot water storage tank. They represent a good balance between efficiency and performance for average- to large-sized homes.
Combination or combi boilers have no tank and only heat water as you need it. They combine the functions of a boiler and a water heater, though the boiler water and domestic water flow through separate pipes. They’re small and cost-effective, but they can struggle to provide hot water to more than one faucet or appliance at once. They’re often used in small houses or apartments.
Hot Water vs. Steam Boilers
Boilers can be further divided into steam and hot water boilers. The latter heats water up to temperatures between 140 degrees Fahrenheit and 180 degrees Fahrenheit, then pumps it through the home’s radiators, baseboard units, or radiant heat systems. Hot water boilers offer greater energy efficiency and control over temperature. In contrast, a steam boiler actually takes water past the boiling point and sends the steam through the home heating system without needing a pump. These produce more heat but take more energy to run.
Condensing vs. Non-Condensing Boilers
Finally, boilers can be condensing or non-condensing. Traditional boilers are non-condensing, which means they waste a bit of heat by venting exhaust fumes. Condensing boilers capture this exhaust and use it for extra heating, making this type of boiler far more efficient and expensive.
Standard vs. High-Efficiency Boilers
Heating efficiency is measured by an annual fuel utilization efficiency (AFUE) rating, which is the percent of fuel energy that gets turned into usable heat. New boilers must have an efficiency rating of 80% or above, but older homes may still have boilers with 55% to 75% efficiency. Boilers marked as high-efficiency have AFUE ratings of 90% or higher.
Electric boilers can have nearly 100% efficiency, and the best gas and propane models can reach 98.5%. Oil boilers top out around 95%, and wood boilers generally reach 90% efficiency. The most efficient boilers are usually condensing combi boilers. High-efficiency models tend to cost a bit more up-front, though you’ll save more in heating costs over time.
Sealed vs. Non-Sealed Boilers
Older boilers may have non-sealed systems. This means they take air from indoors and vent exhaust through your home’s flue—a duct for smoke and waste gases—which requires a special chimney liner. This can be dangerous since there’s a chance exhaust gases like carbon monoxide may accidentally leak indoors. They’re also less efficient since they take in already heated air and waste heat in the form of exhaust. It’s safer and more economical to choose a sealed boiler, which takes in air from outside and re-uses exhaust heat.
Signs You Need a Boiler Replacement
A new boiler is expensive, so you’ll want to keep repairing your old boiler as long as you can. The general rule of thumb is that if you multiply the age of your boiler by the cost to repair it and the result is greater than 5,000, it’s time to replace it. Here are some signs that you need to install a new boiler:
- The boiler is no longer producing sufficient heat.
- Your energy bills are increasing, but the temperature in your home stays the same.
- You hear unusual sounds, like clanging or banging, coming from the boiler.
- The amount of money you’re spending on repairs is increasing.
- You notice leaks or corrosion.
- The boiler is more than 20 years old.
How to Replace a Boiler
If your boiler needs to be replaced, here’s how an HVAC contractor will go about it.
- First, the contractor will determine what size boiler you need. This may differ from the size of your current boiler based on any changes you’ve made to the home’s insulation, windows, doors, roof, etc.
- If the new boiler requires additional intake or exhaust ventilation, as is the case with a sealed condensing system, the contractor will drill any necessary holes and install the vents and piping.
- The contractor will then disconnect the hot and cold water pipes, the supply and return pipes, and the gas connection from the old boiler.
- The contractor will install the new boiler either in the same place as the old boiler or in a new location. The contractor will then reconnect all water and gas pipes.
- If it’s a condensing boiler, the contractor will install a condensate pump to neutralize and pump away the resulting condensation.
- Newer boiler models often have an electronic control panel. If yours does, the contractor will plug or wire the control panel in.
- Your new boiler is ready to use.
DIY Cost to Replace a Boiler
Installing a boiler is not a DIY job. In fact, in most states, you need an HVAC license to install a boiler. These states won’t issue permits to anyone without this license, and a boiler installed by a non-licensed contractor won’t pass inspection.
DIY vs. Professional Boiler Replacement
Simply put, boiler replacement is a job for the professionals. These are large, complex appliances that hook up to plumbing and often gas lines, and for both your safety and the longevity of your home’s heating system, boilers are best installed or replaced by experts. The good news is that you often get a better deal on the boiler itself by purchasing it through a licensed installer.
How to Save on Boiler Replacement Costs
Boiler replacement is expensive. Here a few ways to keep costs low.
- Don’t get a boiler that’s too large or powerful for your home. It will run less efficiently, costing you more in the long run.
- If possible, have your boiler replaced in the summer, when demand for boiler repairs is low. Contractors may offer better rates.
- If you can afford to pay more money up-front, a high-efficiency, condensing boiler will keep your energy bills lower. You could save anywhere from $3,000 to $5,000 throughout your boiler’s 15- to 20-year lifespan.
- Request a cost estimate from multiple HVAC contractors. Be wary of an estimate that seems unusually low, but do reach out to different contractors to see if they may be able to offer you different deals.
- Check if your state has rebates or tax incentives for installing a high-efficiency boiler.
- Buy a boiler with a good warranty.
Installing a boiler isn’t a DIY job. In fact, homeowners must often go through an HVAC contractor to even purchase a boiler, so contact a few to see what they offer. We recommend talking to at least three HVAC professionals to find out what your options are. They can answer your questions and help you choose the best model for your home’s needs.
How to Hire a Contractor for Boiler Replacement
When choosing a contractor to replace your boiler, make sure you find someone with a current HVAC license and experience working on residential boilers. Here are some other things to look for.
- In addition to licensure, make sure the company is bonded and insured.
- Check the company’s Better Business Bureau (BBB) rating as well as customer ratings and reviews.
- Ask for all estimates and any guarantees or warranties in writing. Do the same for any inspections, heating load calculations, or diagrams.
- Ask for itemized costs for all materials and labor.
- Don’t pay the full cost before the work is complete. Always set up a payment schedule.
How Does a Boiler Work?
Unlike a furnace, which uses ductwork to blow hot air through a home, a boiler heats water and sends it through the house to provide radiant heating. When the thermostat registers that the home’s interior has dropped below a certain temperature, it turns the boiler on, generating heat by burning gas, oil, or wood or using electricity. This heat increases the water temperature inside the boiler’s heat exchanger, making it very hot or turning it to steam.
This steam or hot water travels through pipes to your home’s radiators or radiant heating system in the floors or walls. There, the heat is transferred to the ambient air. Cooler water or condensed steam returns to the boiler to be reheated until the thermostat recognizes that the air has reached the set temperature, turning the boiler off.
Frequently Asked Questions
To share feedback or ask a question about this article, send a note to our Reviews team at email@example.com.