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Top Boiler Installation & Replacement Contractors in Bellevue, Washington Ranked
Replacing or installing a new boiler is a significant home improvement decision that directly impacts your comfort, energy bills, and home safety. In Bellevue, this process involves navigating specific local permits, state regulations, and choosing from modern, efficient equipment. This guide is designed to help you understand the key considerations-from boiler types and costs to essential local codes-so you can make an informed choice and connect with qualified professionals for your project.

South West Plumbing, Heating, Air, & Electric
825 S Stacy St, Seattle, WA 98134
South West Plumbing, Heating, Air, & Electric has provided plumbing, HVAC, and electrical services in Seattle, WA for over 40 years. They offer a wide range of services including air conditioning repair and installation, furnace and heat pump repair, boiler installation, and HVAC tune-ups. Their capabilities include advanced drain and sewer services such as hydro jetting and video camera inspections. The company serves residential customers throughout Seattle, delivering comprehensive solutions for heating, cooling, plumbing, and electrical needs.

Energy Saver Solutions Inc - HVAC & Insulation W Seattle
4402 40th Ave SW, Seattle, WA 98116
Energy Saver Solutions Inc - HVAC & Insulation W Seattle provides a range of HVAC services in Seattle, WA. They specialize in air conditioning repair, HVAC installation, boiler and mini split installation, as well as indoor air quality services. The company offers expert attic and crawl space insulation to improve energy efficiency and comfort. With over 30 years of industry experience, Energy Saver Solutions also performs carbon monoxide checks to ensure safety. They provide 24/7 emergency service and are available year-round to support heating and cooling needs in all weather conditions.

Energy Saver Solutions Inc - HVAC & Insulation SW Seattle
1414 SW 114th St, Seattle, WA 98146
Energy Saver Solutions Inc - HVAC & Insulation SW Seattle provides comprehensive HVAC and insulation services in Seattle, WA. They specialize in air conditioning repair, HVAC and boiler installation, mini split systems, and indoor air quality services. The company offers expert attic and crawl space insulation to improve energy efficiency and comfort. With over 30 years of industry experience, they also provide carbon monoxide testing and 24/7 emergency service availability to address urgent heating and cooling needs.

Energy Saver Solutions Inc - HVAC & Insulation Redmond WA
6917 132nd Pl NE, Redmond, WA 98052
Energy Saver Solutions Inc - HVAC & Insulation Redmond WA provides a range of HVAC services in Seattle, WA, including air conditioning repair, boiler and mini split installation, indoor air quality services, and insulation solutions for attics and crawl spaces. The company specializes in energy-saving strategies and offers carbon monoxide checks to ensure safety. With over 30 years of industry experience, they serve both residential and commercial clients. Their technicians are available 24/7, including holidays, to address urgent heating and cooling needs.

AAA Heating & Air Conditioning
4150 Lind Ave SW, Renton, WA 98057
AAA Heating & Air Conditioning is a local HVAC contractor serving Seattle, WA, and the surrounding Puget Sound area. They offer a wide range of heating and cooling services including installation, repair, and maintenance for air conditioners, furnaces, heat pumps, and boilers. The company also provides indoor air quality services such as duct cleaning and duct sealing to help improve home air quality. With over 30 years of experience since 1989, AAA Heating & Air Conditioning is equipped to handle common repairs efficiently with fully stocked trucks and offers 24/7 emergency service for air conditioning issues.
Understanding Your Boiler Options
Modern boilers are far more efficient and versatile than older models. Selecting the right type for your Bellevue home depends on your heating needs, existing infrastructure, and long-term energy goals.
- Standard/Mid-Efficiency Boilers: These are basic gas or oil-fired units. They typically have a lower upfront cost but operate at lower Annual Fuel Utilization Efficiency (AFUE) ratings, meaning more of your fuel dollar is wasted. They are often a straightforward replacement for older, similar systems 1.
- High-Efficiency Condensing Boilers: This is the contemporary standard for new installations. These units achieve AFUE ratings of 90% or higher by capturing heat from exhaust gases that would otherwise be vented out. The higher initial investment is usually offset by substantial long-term energy savings, making them a smart choice for most Bellevue homes 2.
- Combi Boilers (Combination): A popular space-saving option, a combi boiler provides both space heating and on-demand domestic hot water from a single, compact unit. It operates like a tankless water heater for your taps and showers while also powering your radiators or baseboards. This eliminates the need for a separate water heater tank 3.
- Hydronic Systems: This refers to the method of heat distribution. Most residential boilers are part of a hydronic (hot water) system, where heated water is circulated through radiators, baseboard heaters, or in-floor radiant tubing. Some older systems may use steam, which has different requirements.
Navigating Bellevue and Washington State Regulations
A successful boiler installation is a permitted and inspected project. Adhering to local and state codes is not just a legal formality; it ensures the safety and efficiency of your system.
City of Bellevue Mechanical Permit: Any work involving the installation, replacement, or alteration of a boiler system requires a mechanical permit from the City of Bellevue. Your contractor typically pulls this permit, which triggers necessary inspections to verify the work meets code.
Washington State L&I Oversight: The Washington State Department of Labor & Industries (L&I) has specific jurisdiction over boilers. An L&I permit is required for the installation or reinstallation of a boiler, followed by an inspection. There are associated fees for these services that are separate from city permits.
Key Safety Code Requirements: The Washington State Residential Code, adopted by Bellevue, outlines critical installation standards (M2001.1). Key mandates include:
- Installation per the manufacturer's instructions.
- A permanent boiler nameplate.
- Properly set and installed controls.
- Adequate combustion air supply.
- Approved shutoff valves.
- A properly sized and installed pressure relief valve.
- A low-water cutoff device to prevent damage if water levels drop 4.
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Cost Factors for Boiler Replacement in Bellevue
The total investment for a new boiler system can vary widely based on equipment choices and the scope of work needed for your specific home.
General Cost Range: For a full residential boiler replacement in the Bellevue area, homeowners can expect a typical range of $4,000 to $10,000 or more, including equipment, labor, and permits 5 6. A standard high-efficiency condensing boiler installation often falls between $6,000 and $8,500+ 5.
Variables That Influence Price:
- Equipment Type & Efficiency: High-efficiency condensing and combi boilers have a higher equipment cost than standard models.
- System Size & Complexity: Larger homes require larger, more expensive boilers. The complexity of your existing hydronic piping can affect labor time.
- Fuel Conversion: Switching from an old oil-fired boiler to a new gas model involves removing the oil tank and potentially running new gas lines, which can add $2,000 or more to the project cost.
- Ancillary Work: Upgrading electrical service, adding new piping runs, or installing a new flue liner for a high-efficiency unit will increase costs.
- Removal & Disposal: Professionally removing and disposing of the old boiler and related equipment typically costs between $500 and $1,000 7.
Planning Your Boiler Project: A Step-by-Step Guide
- Get a Proper Sizing Estimate: An oversized boiler cycles on and off inefficiently, while an undersized one won't keep you comfortable. Contractors perform a heat load calculation, but a very rough starting estimate is around 35 BTU per square foot of living space 8. A qualified professional will provide a precise calculation.
- Verify Permit Requirements: Confirm that any contractor you consider will handle pulling the required City of Bellevue mechanical permit and the Washington L&I boiler permit. This is a hallmark of a legitimate, code-compliant operation 9 10.
- Evaluate Equipment Choices: Discuss the pros and cons of high-efficiency condensing and combi boilers with potential installers. While the upfront cost is higher, the long-term energy savings in Bellevue's climate can be significant, offering a strong return on investment over the system's lifespan.
- Hire a Qualified Contractor: This is the most critical step. Seek licensed, insured professionals with specific experience in boiler installations who are familiar with both Bellevue's local amendments and Washington State's L&I requirements. They should provide a detailed written estimate that includes all equipment, labor, permit fees, and a description of the work to be performed.
Frequently asked questions
Sources
Footnotes
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How Much Does Residential Boiler Installation Cost? - Aero Energy - https://www.aeroenergy.com/how-much-does-residential-boiler-installation-cost/ ↩
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Chapter 20 Boilers and Water Heaters: Boilers and Water Heaters, Washington State Residential Code 2021 | UpCodes - https://up.codes/viewer/washington/wa-residential-code-2021/chapter/20/boilers-and-water-heaters ↩
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Different Types of Boiler - Combi or Conventional - https://www.yourlocalplumbingcompany.co.uk/Heating-and-Gas/new-boiler-install/what-type-of-boiler/ ↩
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2021 Bellevue Residential Code - M2001.1 Installation. - https://codes.iccsafe.org/s/WABellevueRC2021P1/part-v-mechanical/WABellevueRC2021P1-Pt05-Ch20-SecM2001.1 ↩
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Boiler Replacement Costs: Smart Budgeting and Planning ... - https://www.tcmemt.com/post/the-cost-of-boiler-replacement-expert-guide-to-smart-budgeting-and-installation-planning ↩ ↩2
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How Much Does Boiler Replacement Cost in Seattle? [2026 Data] - https://www.angi.com/articles/how-much-does-boiler-installation-cost/wa/seattle ↩
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How Much Does Boiler Replacement Cost? (2026) - This Old House - https://www.thisoldhouse.com/heating-cooling/boiler-replacement-cost ↩
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What Size Boiler Do I Need for My House? A Complete Guide - https://greenenergymech.com/blog/what-size-boiler-need-for-house/ ↩
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Mechanical Permits | City of Bellevue - BellevueWA.gov - https://bellevuewa.gov/city-government/departments/development/permits/electrical-mechanical-plumbing-permits/mechanical-permits ↩
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Permits, Fees & Inspections - Lni.wa.gov - https://www.lni.wa.gov/licensing-permits/boilers/permits-fees-inspections ↩