Weil-McLain SlimFit Commercial Condensing Boiler Installation Chicago
Weil-McLain Condensing Commercial Boilers
SlimFit® Commercial Condensing Gas Boiler
High-efficiency condensing design. 95% AFUE. up to 1,000,000 BTU/hr. Fits through standard doorways — ideal for Chicago mechanical room retrofits.
Weil-McLain SlimFit® — Chicago's High-Efficiency Retrofit Boiler
The Weil-McLain SlimFit® is a high-efficiency condensing commercial gas boiler purpose-built for retrofit installations in existing Chicago buildings. Its defining feature is a narrow profile that fits through a standard 32-inch doorway — eliminating the need for wall demolition or crane lifts that conventional large commercial boilers require.
With 95% AFUE and a modulating burner, the SlimFit® dramatically reduces fuel consumption compared to the atmospheric boilers it replaces. Four models from 399,000 to 1,000,000 BTU/hr cover mid-size commercial buildings, multi-unit residential properties, schools, and institutional facilities throughout Chicago.
D's Air & Heating, Inc. installs the SlimFit® throughout Chicago and the southwest suburbs. We handle all City of Chicago commercial mechanical permits, PVC venting, system piping, controls, and startup — and register your Weil-McLain warranty before we leave the job.
Why D's Air & Heating, Inc. Installs the SlimFit®
95% AFUE Condensing
High-efficiency condensing design recovers heat from flue gases — dramatically reducing fuel costs in Chicago's long heating season.
Fits Through Standard Doors
The SlimFit's narrow profile is engineered to pass through a standard 32-inch doorway — the critical advantage for Chicago mechanical room retrofits.
Direct Vent / PVC
Vents with standard PVC pipe — no chimney required. Ideal for Chicago buildings without existing flue infrastructure.
399K–1,000,000 BTU/hr
Four models cover mid-size commercial buildings, multi-unit residential, and institutional facilities throughout Chicago.
Modulating Burner
Modulating operation matches output to actual heating demand — reducing short-cycling and improving comfort in variable-load Chicago buildings.
Weil-McLain Warranty
Backed by Weil-McLain's limited warranty. D's Air & Heating, Inc. registers your warranty at startup.
SlimFit® — Models & Specs
| Model | BTU/hr Input | Efficiency | Fuel | Venting | Installed Price |
|---|---|---|---|---|---|
| SlimFit 399 | 399,000 | 95% AFUE | Natural Gas / Propane | Direct Vent / PVC | Get a Free Estimate |
| SlimFit 500 | 500,000 | 95% AFUE | Natural Gas / Propane | Direct Vent / PVC | Get a Free Estimate |
| SlimFit 750 | 750,000 | 95% AFUE | Natural Gas / Propane | Direct Vent / PVC | Get a Free Estimate |
| SlimFit 1000 | 1,000,000 | 95% AFUE | Natural Gas / Propane | Direct Vent / PVC | Get a Free Estimate |
SlimFit 399
399,000 · 95% AFUE
Natural Gas / Propane · Direct Vent / PVC
Get a Free Estimate
SlimFit 500
500,000 · 95% AFUE
Natural Gas / Propane · Direct Vent / PVC
Get a Free Estimate
SlimFit 750
750,000 · 95% AFUE
Natural Gas / Propane · Direct Vent / PVC
Get a Free Estimate
SlimFit 1000
1,000,000 · 95% AFUE
Natural Gas / Propane · Direct Vent / PVC
Get a Free Estimate
*Local taxes may apply. Call for current installed pricing.
What's Included in Every SlimFit® Installation
- Complete removal and disposal of existing boiler
- New Weil-McLain SlimFit® boiler — properly sized for your building
- PVC direct-vent flue installation (no chimney required)
- Gas supply line connection and pressure test
- System piping, supply and return connections
- Expansion tank, pressure relief valve, and air separator
- Thermostat and zone control wiring
- City of Chicago commercial mechanical permit (when required)
- Full system startup, combustion analysis, and efficiency verification
- Weil-McLain warranty registration
Weil-McLain Boiler Installation & Service Experts
D's Air & Heating proudly provides professional Weil-McLain boiler installation, replacement, repair, maintenance, and emergency service throughout Chicago and surrounding communities. Weil-McLain is recognized as one of the most trusted names in the boiler industry, delivering reliable heating solutions for residential, commercial, steam, and hot water applications.
Our experienced boiler technicians install and service a wide range of Weil-McLain commercial equipment. Whether you need a new Weil-McLain boiler installation Chicago businesses rely on, complete boiler replacement, annual maintenance, or emergency repair service, D's Air & Heating has the expertise to keep your commercial heating system operating safely and efficiently.
From small commercial buildings to large boiler plant projects, D's Air & Heating delivers quality workmanship, expert system design, and dependable customer support backed by industry-leading Weil-McLain technology and warranty protection. Our Weil-McLain boiler repair Chicago commercial customers trust us for fast diagnostics, genuine parts, and lasting fixes.
Contact D's Air & Heating today at (773) 940-0965 to schedule your free estimate for Weil-McLain boiler installation, replacement, maintenance, or repair services.
Get a SlimFit Commercial Boiler Estimate
D's Air & Heating, Inc. installs the Weil-McLain SlimFit throughout Chicago and the southwest suburbs. Call (773) 940-0965 or book online for a free commercial estimate.
Related Weil-McLain Commercial Boilers
Why Chicago Homeowners Trust D's Air & Heating
Licensed & Insured
IL License #2183457
Serving Chicago
Since 2009
Authorized Dealer
Multiple Brands
No Contracts
Ever — Guaranteed
Permit Pulled
Every Installation
Professional Standards
Code-Compliant Work
EPA Certified
Mainstream Engineering
R-410A Certified
Mainstream Engineering
Why Choose D's Air & Heating, Inc.?
Chicago's trusted HVAC company since 2009 — licensed, insured, and committed to honest workmanship on every job.
Experience Since 2009
D's Air & Heating has served Chicago homeowners and businesses since 2009. Over 15 years of local HVAC experience means we've seen every type of system, every Chicago building configuration, and every challenge the city's climate presents.
Manufacturer-Trained Technicians
Our technicians receive ongoing manufacturer training and certification. We install Lennox, Goodman, Amana, Daikin, Sinclair, Weil-McLain, Peerless, and other leading brands — and we know each system inside and out.
Licensed, Insured & Permitted
D's Air & Heating holds Illinois HVAC License #2183457 and carries full liability insurance. We pull City of Chicago permits on every installation — protecting you legally and ensuring the work meets code.
Honest Recommendations
We tell you what you need — not what generates the highest invoice. If your system can be repaired cost-effectively, we'll say so. If replacement makes more sense, we'll explain exactly why. No pressure, no upselling.
Local Chicago Expertise
We know Chicago's housing stock — two-flats, greystones, bungalows, vintage buildings with steam heat, modern construction with forced air. We size and install equipment for the specific demands of Chicago homes and Chicago winters.
Long-Term Customer Support
Our relationship doesn't end at installation. We register your equipment for warranty, remain available for follow-up questions, and provide ongoing maintenance to keep your system running at peak efficiency for years.
Commercial HVAC in Chicago — What Building Owners Should Know
Commercial vs. Residential HVAC
Commercial HVAC systems are designed for larger spaces, higher occupancy loads, and continuous operation. Rooftop packaged units (RTUs) are the most common commercial heating and cooling solution in Chicago — they combine heating, cooling, and ventilation in a single cabinet mounted on the roof. Commercial systems require more complex controls, larger electrical service, and more rigorous maintenance than residential equipment.
Rooftop Unit Selection and Sizing
Commercial RTUs are sized in tons of cooling capacity, from 3 tons for small retail spaces to 50+ tons for large commercial buildings. Proper sizing requires calculating cooling load (heat gain through walls, roof, windows, occupancy, and equipment) and heating load. Oversized RTUs short-cycle, causing temperature swings and premature compressor wear. D's Air performs commercial load calculations on every project.
Permits and Code Compliance
Commercial HVAC work in Chicago requires mechanical permits from the City of Chicago Department of Buildings. Work must comply with the Chicago Building Code, ASHRAE 90.1 energy standards, and ASHRAE 62.1 ventilation requirements. D's Air handles all permit applications and inspections for commercial projects.
Preventive Maintenance Contracts
Commercial HVAC equipment operates year-round under heavy loads. Preventive maintenance — quarterly or semi-annual inspections, filter changes, coil cleaning, belt and bearing checks, refrigerant verification — extends equipment life and prevents costly emergency failures. D's Air offers commercial maintenance contracts tailored to your building's equipment and schedule.
What to Expect From D's Air Commercial HVAC Services
Site Assessment
We visit your building, assess existing equipment and infrastructure, and identify project requirements.
Engineering
We perform load calculations, equipment selection, and permit drawings for your project.
Permitting
We handle all City of Chicago permit applications and coordinate inspections.
Installation
Our commercial crew installs equipment to code, including crane lifts for rooftop units.
Commissioning
We test all equipment, verify airflow and refrigerant charge, and document system performance.
Ongoing Support
We offer preventive maintenance contracts and priority emergency service for commercial clients.
D's Air Commercial HVAC Standards
- Commercial load calculation — cooling and heating
- Equipment selection per ASHRAE 90.1 energy standards
- Ventilation design per ASHRAE 62.1
- City of Chicago mechanical permit on every project
- Crane lift coordination for rooftop equipment
- Curb adapter fabrication for non-standard roof openings
- BAS/BMS integration where required
- Commissioning documentation provided
- Preventive maintenance contracts available
What Our Customers Say
Based on Google Reviews — D's Air & Heating, Inc.
Marcus T.
Furnace Replacement
"D's Air & Heating did an outstanding job replacing my furnace. Darryl was professional, on time, and explained everything clearly. The installation was clean and the system works perfectly. Highly recommend."
Latoya W.
Boiler Repair
"Called D's Air when my boiler stopped working in January. They came out the same day, diagnosed the problem quickly, and had it running again within hours. Fair pricing and excellent service."
James R.
AC Installation
"Installed a new central AC system for us this summer. The crew was respectful of our home, cleaned up after themselves, and the system runs quietly and efficiently. Very satisfied."
Ready to Work With Chicago's Trusted HVAC Company?
D's Air & Heating, Inc. — Serving Chicago Since 2009. Licensed, Insured, No Contracts.