When Mike Sanders decides to upgrade to a 100,000 BTU boiler like the Weil-McLain CGA-4 Series 3, one of the first questions he’s asking is: Will it fit in my utility room without needing a remodel? This guide answers that—breaking down everything from unit dimensions to airflow clearances and even noise levels.
Whether you're upgrading from an old boiler or designing a new mechanical space, here's what you need to know.
📐 1. CGA-4 Boiler Dimensions and Footprint
🔧 Boiler Specs (from Weil-McLain)
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Width: 19.75 inches
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Depth: 23 inches
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Height: 30.75 inches
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Weight: ~335 pounds (without water)
➡️ Footprint: Roughly 3.2 sq. ft., making it compact for its BTU class
📄 Weil-McLain CGA-4 Spec Sheet
📏 2. Required Clearances (Per Code and Manufacturer)
The CGA-4 is an atmospheric vent, cast iron boiler, so it requires:
| Side | Minimum Clearance |
|---|---|
| Front (for service access) | 24 inches |
| Rear | 6 inches |
| Left/Right | 6 inches |
| Top | 12 inches (to ceiling) |
| Flue Pipe | 6 inches (to combustibles) |
➡️ Total space needed: At least 42” wide × 47” deep × 7' high for service and airflow.
🛠️ Tip: Leave extra space for elbow room around valves, gas shutoff, and circulators.
🌬️ 3. Combustion Air and Ventilation
Gas boilers like the CGA-4 need access to adequate combustion air. If installed in a small or sealed utility closet, code requires one of the following:
🔲 Option A: Grille/Openings
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One opening 12” from top and one 12” from bottom of door/wall
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Minimum: 1 sq. inch per 1,000 BTUs of input
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CGA-4 = 100 sq. in. top + 100 sq. in. bottom
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🔲 Option B: Louvered Door
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Door with louvers sized for same 200 sq. in. total (or more)
🔲 Option C: Ducted Air Intake
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Use of ductwork from exterior to bring in combustion air
📘 IRC 2021 Section G2407.5 – Combustion Air Requirements
➡️ Mike’s Tip: If your utility room shares space with laundry or storage, consider ducted air to prevent negative pressure.
🚪 4. Doorway, Stairs & Installation Path Clearance
Before delivery day, verify:
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Minimum door width: 26 inches (for boiler + wiggle room)
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Stairway corners: Boiler weighs ~335 lbs, may need dolly or appliance lift
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No obstacles between exterior and final install site
🏗️ Optional: Ask your installer if the CGA-4 can be partially disassembled to fit tight doorways.
➡️ Installers will charge extra if your home requires rerouting or temporary demo.
🔊 5. Noise Levels: Will It Be Loud?
The CGA-4 is a natural-draft, non-condensing boiler, so it runs quietly with:
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No blower motor (like high-efficiency condensing models)
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Low combustion noise
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Mild expansion/contraction sounds during startup
📊 Estimated noise level: ~35–45 dB (same as a quiet refrigerator)
➡️ Install it on a concrete slab or rubber isolation pad to further reduce vibration.
🔌 6. Utility Room Electrical & Drainage Needs
Although the CGA-4 uses standing pilot ignition (no power needed for flame), it requires:
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120V outlet nearby for circulator pump, zone valves, or thermostats
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Condensate drain (optional) for indirect water heater connections
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Floor drain or secondary containment pan to manage overflows
🧯 Pro Tip: Install a water sensor shutoff valve to catch hidden leaks early.
🧰 7. Leave Room for Maintenance Access
Mike knows future service is inevitable. Build in space to:
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Remove and clean burners
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Access relief valve, pressure gauge, and drain
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Swap circulators or expansion tank
📏 Plan for 24 inches of front access minimum.
➡️ Boilers stuffed in closets cost more to service and are harder to troubleshoot.
🧱 8. Placement Tips from Installers
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Don’t place the unit under shelving or overhangs
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Avoid stacking storage bins near intake vents
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Leave a clear path to boiler for emergency shutoff
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Place labels for water/gas shutoff and boiler circuit breaker
🚫 Do not install in:
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Bedrooms
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Bathrooms
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Attics without vented access
📋 NFPA 54 – National Fuel Gas Code Appliance Location Requirements
✅ Conclusion: Will the CGA-4 Fit?
Yes—for most utility rooms, mechanical spaces, or unfinished basements, the Weil-McLain CGA-4 Series 3 fits comfortably as long as:
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You allow proper front and side clearances
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You have at least 42"×47" of usable space
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Combustion air is available via grilles or duct
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Noise and electrical needs are considered
For Mike Sanders, it’s a compact, quiet, code-compliant system with minimal footprint—and no surprises after installation.
In the next topic we will know more about: How to Tell If It’s Time to Replace Your Old Boiler (Before It Breaks Down in Winter)
