When I decided to replace my old boiler with the Weil-McLain CGI-4 Series 4 (90,000 BTU cast iron natural gas boiler), I thought the hard part would be choosing the brand. But as I dug deeper, I realized the real question wasn’t just which boiler to buy, but what will it actually cost me over the next 20 years?
That’s when I started breaking down the costs into four categories:
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Equipment
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Installation
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Energy use & maintenance
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Long-term value
Here’s the full breakdown I wish I had before I started shopping.
🛠️ Equipment Costs
The price you see online or in the showroom is just the starting point.
Weil-McLain CGI-4 Price Range
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$2,800–$3,400 for the boiler unit itself (equipment only).
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Price varies by supplier, region, and whether it includes bundled accessories.
Accessories & Add-Ons
Most installs require more than just the boiler:
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Expansion tank: $75–$150
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Circulator pump: $200–$400
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Air separator: $100–$200
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Relief valve & safeties: $50–$150
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Thermostat upgrade (optional): $150–$300
👉 Total equipment costs can easily reach $3,500–$4,200 before installation.
🔗 Weil-McLain Gas Boilers Product Line
💡 Mike’s Note: Don’t forget to budget for accessories — they’re often sold separately but absolutely required.
👷 Installation Costs
Here’s where most homeowners (including me) get sticker shock. The labor and extras often cost more than the boiler itself.
Labor
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$3,000–$5,000 is typical for professional installation.
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Cost varies based on region, contractor experience, and how much retrofitting is needed.
Piping & Connections
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Replacing old piping, valves, or manifolds: $500–$1,200.
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New isolation valves and ball valves are worth it for future maintenance.
Chimney & Venting
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Stainless steel chimney liner: $400–$1,000.
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Draft hood and vent pipe adjustments: $150–$300.
Gas & Electrical Work
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Upgraded gas line (if needed): $200–$500.
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Electrical hookup and emergency shutoff switch: $150–$300.
👉 Total installed cost often falls in the $6,500–$10,000 range.
💡 Mike’s Note: I budgeted $7,000 for my CGI-4 install and ended up at $7,600 after venting upgrades and extra valves.
⚡ Energy Use & Operating Costs
Upfront costs are only half the story. Boilers are long-term systems, and energy bills add up.
Gas Consumption
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CGI-4 input: 90,000 BTUs/hr at ~82–84% AFUE.
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Actual fuel burned: ~110,000 BTUs/hr.
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At $1.30/therm, an hour of runtime costs about $1.40.
Winter Heating Bills (Typical Range)
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Small, well-insulated home: $100–$150/month.
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Mid-sized home (like mine): $150–$250/month.
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Poorly insulated home: $250–$400/month.
Annual Tune-Up
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Professional inspection & cleaning: $150–$300/year.
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Keeps efficiency high and prevents expensive repairs.
Repairs (Over 20 Years)
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Circulator pump: $400
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Relief valve: $150
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Control board/aquastat: $300–$600
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Total expected repair costs: ~$1,500–$2,000 over the lifespan.
🔗 Energy Star – Boiler Efficiency Guide
💡 Mike’s Note: My old boiler ran dirty and cost me $50–$75 more per month in gas. A tune-up is cheap insurance.
⏳ Long-Term Value
This is where the Weil-McLain CGI-4 really shines compared to alternatives.
Lifespan
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20–30 years is common for cast iron boilers with proper maintenance.
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Condensing boilers often last only 12–15 years due to more complex components.
Reliability
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Fewer electronics = fewer failures.
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Cast iron heat exchanger = durable and corrosion-resistant.
Resale Value
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A newer boiler makes your home more attractive to buyers.
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Buyers see updated heating systems as a sign the home was well cared for.
Return on Investment
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Payback comes through lower repair costs and longevity rather than efficiency.
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While condensing boilers save more on gas, they cost more upfront and don’t last as long.
🔗 This Old House – Boiler Lifespan & Maintenance
💡 Mike’s Note: For me, the peace of mind of a 25-year boiler was worth more than chasing an extra 10% efficiency.
📊 Real-World Cost Example: My Install
Here’s how my numbers shook out:
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Boiler & accessories: $3,800
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Installation & labor: $3,500
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Venting upgrades: $400
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Gas/electric adjustments: $200
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Total upfront: $7,900
Annual Operating Costs
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Gas: ~$1,500/year
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Tune-up: $200/year
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Average total: $1,700/year
20-Year Ownership
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Upfront: $7,900
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Gas (20 years): $30,000+ (depends on rates)
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Maintenance/repairs: $3,500
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Grand total: ~$41,000 over 20 years
That sounds big, but remember: heat is the largest energy expense in most homes.
🔗 EPA – Energy Efficiency at Home
📋 Mike’s Final Word
The true cost of a boiler isn’t just the price tag. It’s the combination of:
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Upfront equipment ($3,000–$4,000)
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Installation ($3,500–$6,000)
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Operating costs (~$1,500–$2,500/year)
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Long-term value (25+ years of reliable heat)
👉 In my experience, the Weil-McLain CGI-4 delivers great value because it balances upfront cost with reliability. While I spent close to $8,000 to install, I won’t be replacing it for decades — and that’s money well spent.
If you’re planning your budget, remember: paying for quality upfront saves you money and headaches later.
In the next topic we will know more about: Cast Iron Boiler Longevity: Why Mike Still Trusts Weil-McLain
