Dunkirk WPSB Series 4 Gas Boiler
Mid-efficiency cast iron hot-water boiler — 7 sizes, up to 84.1% AFUE, Fuel Smart Hydrostat 3-in-1 control, and a 20-year non-prorated warranty.
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Boiler Type
Cast Iron Gas Boiler
AFUE Efficiency
Up to 84.1% AFUE
Fuel Type
Natural Gas / Propane
Heat Exchanger
Cast Iron Sections
Application
Residential Hot Water Heating
Venting Type
Category I / B-Vent (Chimney)
Installation Type
Floor Standing
Get Your Free Estimate
Dunkirk WPSB Series 4 — Built for Chicago Homes
The Dunkirk WPSB Series 4 is a mid-efficiency gas-fired hot-water boiler available in 7 sizes with an AFUE rating up to 84.1%. It features the advanced Fuel Smart Hydrostat 3-in-1 Control, combining temperature limit control, low-water cutoff protection, and boiler reset functionality to reduce fuel consumption and improve system efficiency.
The WPSB includes an integral draft hood and vent damper, reducing overall height and making it ideal for low-clearance or space-limited installations. Its compact footprint and Cast-to-Last 20-Year Non-Prorated Limited Warranty make it a strong choice for residential hot-water heating applications throughout Chicago.
Key Features
Fuel Smart Hydrostat 3-in-1
Combines temperature limit, low-water cutoff, and boiler reset in a single control module — no outdoor sensor required.
20-Year Non-Prorated Warranty
Dunkirk's Cast-to-Last warranty covers the heat exchanger for 20 years, non-prorated — one of the strongest in the industry.
Cast Iron Heat Exchanger
Cast iron sections with push nipples deliver long-lasting, even heat transfer and resist corrosion over decades of use.
Integral Draft Hood & Vent Damper
Built-in draft diverter and vent damper reduce overall unit height — ideal for low-clearance mechanical rooms.
Low Water Cutoff (LWCO)
Factory-installed LWCO protects the boiler from dry-fire damage — a critical safety feature for Chicago hot-water systems.
Compact Footprint
Seven sizes from 75–299 MBH (NG) fit tight Chicago basement and utility-room installations without sacrificing output.
Technical Specifications
| Efficiency | Mid-Efficiency — up to 84.1% AFUE |
| Boiler Type | Hot Water |
| Heat Exchanger | Cast Iron Sections with Push Nipples |
| Combustion | Atmospheric |
| Venting | Chimney Vent — Integral Draft Diverter + Vent Damper |
| Gas Types | Natural Gas (D models) / Propane (DP models) |
| Sizes Available | 7 (3–9 sections) |
| Warranty | 20-Year Non-Prorated Limited (Cast-to-Last) |
| Functions | Temperature limit, LWCO, Boiler Reset |
| Display | LED temperature display |
| Settings | Dial-type adjustments |
| Diagnostics | Indicator lights |
| Outdoor Sensor | Not required for boiler reset |
| Circulator Relay | Included |
| DHW Override | Domestic hot water input override |
| Ignition | 24V intermittent pilot, continuous retry |
Capacity Ranges
D models = Natural Gas · DP models = Propane
| Model | Input MBH | Output MBH | Sections |
|---|---|---|---|
| WPSB-3D | 75 | 63 | 3 |
| WPSB-4D | 112.5 | 94.5 | 4 |
| WPSB-5D | 150 | 126 | 5 |
| WPSB-6D | 187.5 | 157.5 | 6 |
| WPSB-7D | 225 | 189 | 7 |
| WPSB-8D | 262 | 220 | 8 |
| WPSB-9D | 299 | 251 | 9 |
| Model | Input MBH | Output MBH | Sections |
|---|---|---|---|
| WPSB-3DP | 70 | 58.8 | 3 |
| WPSB-4DP | 105 | 88.2 | 4 |
| WPSB-5DP | 140 | 117.6 | 5 |
| WPSB-6DP | 175 | 147 | 6 |
| WPSB-7DP | 210 | 176.4 | 7 |
| WPSB-8DP | 245 | 205.8 | 8 |
| WPSB-9DP | 280 | 235.2 | 9 |
Safety Features & Included Components
Safety Features
- Flame roll-out safety shut-off (fuse link)
- Blocked vent safety shut-off (manual reset disc thermostat)
- Built-in Low Water Cutoff (LWCO)
- Automatic redundant gas valve
- 100% shut-off on continuous retry
- Spare fuse link included
- ASME 30 lb. pressure relief valve
- Temperature/pressure gauge
Included Components
- Insulated boiler jacket
- Integral draft diverter
- Vent damper
- Temperature/pressure gauge
- Circulator pump (wired with 5′ harness — supply or return mounting)
- ¾″ drain valve
- 30 lb. ASME relief valve
Available Options
What's Included in the Installation
Installation Notes
- Most WPSB replacements complete in a single day — minimal disruption to your home.
- D's Air pulls all required City of Chicago permits for every boiler installation.
- The integral draft hood and vent damper reduce unit height — ideal for tight mechanical rooms.
- Circulator pump ships pre-wired with a 5′ harness for supply or return mounting flexibility.
- Compatible with Fill-Trol expansion tank systems for closed-loop hot-water applications.
- Natural Gas and Propane conversion kits available for fuel-type changes at time of install.
- High-altitude conversion kits available for installations above 2,000 ft elevation.
- All installations include startup, system pressure test, and combustion verification.
Why D's Air & Heating, Inc.
Installed pricing below includes equipment, labor, City of Chicago permits, startup, and a 1-year workmanship warranty. No hidden fees.
Small (75–112.5 MBH)
$6,950
WPSB-3D / WPSB-4D — single-family homes up to ~1,400 sq ft
Medium (150–187.5 MBH)
$7,950
WPSB-5D / WPSB-6D — single-family homes up to ~2,400 sq ft
Large (225–262 MBH)
$9,250
WPSB-7D / WPSB-8D — two-flats, larger single-family homes
XL (299 MBH)
$10,450
WPSB-9D — large two-flats, greystones, multi-zone systems
Service Call Policy — D's Air & Heating, Inc.
- 1Fee covers travel and full diagnostics only.
- 2Fee is not deducted from repair or installation cost.
- 3After diagnostics, clear repair/replacement options with upfront itemized pricing.
- 4Once Maintenance Agreement approved, 15% discount activates and applies to repair/installation estimate.
- 515% discount does not apply to the initial service call fee.
A $95.35 Service Call Fee is Required for All Service Appointments, Including Warranty Claims.
Trusted American Boiler Technology
Dunkirk has been manufacturing dependable heating equipment in Dunkirk, New York since 1928. For nearly a century, Dunkirk has built a reputation for durable cast iron construction, reliable atmospheric combustion, and heating systems that stand the test of time. The WPSB Series 4 represents the latest evolution of Dunkirk's cast iron hot water boiler lineup — combining proven cast iron durability with the intelligent Fuel Smart Hydrostat 3-in-1 control system.
The WPSB Series 4's Fuel Smart Hydrostat 3-in-1 control is what sets it apart from conventional cast iron boilers. This integrated control module combines temperature limit protection, low-water cutoff, and boiler reset in a single unit — eliminating the need for an outdoor sensor while providing intelligent, weather-responsive operation. The boiler reset function automatically adjusts water temperature based on heating demand, reducing fuel consumption and improving comfort throughout the heating season.
Cast iron construction is the foundation of the WPSB's durability. The heavy-duty cast iron sections with push nipples provide exceptional heat retention and thermal mass, maintaining comfortable temperatures even during Chicago's coldest nights. Cast iron resists corrosion and thermal stress, contributing to a service life that can exceed 30 years with proper annual maintenance. Dunkirk backs this durability with a 20-year non-prorated Cast-to-Last warranty on the heat exchanger.
For Chicago homeowners with existing hot water radiator or baseboard systems, the WPSB Series 4 is a direct replacement that works with your existing distribution system. Seven sizes from 75 to 299 MBH ensure proper sizing for every application, from small single-family homes to large multi-unit buildings. Natural gas and propane configurations are available, and the compact footprint fits tight Chicago basement and utility-room installations.
Common Applications
What Chicago Customers Say
⭐⭐⭐⭐⭐ 4.9/5 Customer Satisfaction
"D's Air installed a Dunkirk WPSB in our two-flat and the difference is remarkable. The Hydrostat control keeps the water temperature just right and our gas bills are noticeably lower. Darryl's team was professional and had everything done in one day."
Robert H.
Wicker Park, Chicago
"We had an old boiler that was constantly cycling on and off. D's Air replaced it with the Dunkirk WPSB Series 4 and the house heats evenly now. They explained the new control system clearly and the installation was clean and professional."
Angela D.
Avondale, Chicago
"Called D's Air when our boiler stopped working in February. They came out quickly, diagnosed the problem, and recommended the WPSB as the right replacement for our home. Installation was done the next day. Great service."
Thomas B.
Irving Park, Chicago
"D's Air has been our HVAC company for years. When it was time to replace our boiler, they recommended the Dunkirk WPSB and we couldn't be happier. The new control system is much smarter than our old boiler and the heat is more consistent throughout the house."
Maria C.
Portage Park, Chicago
Frequently Asked Questions
How long does a Dunkirk WPSB installation take?
Most WPSB boiler replacements are completed in a single day. New installations may take one to two days depending on piping and venting complexity. D's Air & Heating minimizes disruption throughout the process.
What makes the WPSB Series 4 different from other cast iron boilers?
The WPSB Series 4 features Dunkirk's Fuel Smart Hydrostat 3-in-1 control, which combines temperature limit, low-water cutoff, and boiler reset in a single module — no outdoor sensor required. This simplifies installation and provides intelligent, efficient operation.
Is financing available for a WPSB installation?
Yes. D's Air & Heating offers financing options for qualified customers. Ask about current financing programs when you call for your free estimate.
How often should the WPSB be serviced?
Annual maintenance is recommended before each heating season. Regular service includes cleaning the heat exchanger, inspecting the burners and controls, checking safety devices, and verifying combustion efficiency.
What warranty comes with the Dunkirk WPSB Series 4?
The WPSB Series 4 includes Dunkirk's Cast-to-Last 20-year non-prorated limited warranty on the heat exchanger — one of the strongest residential boiler warranties available.
Is the WPSB a hot water or steam boiler?
The WPSB Series 4 is a hot water boiler only. It is designed for hydronic heating systems with radiators, baseboard heaters, or radiant floor heating. For steam systems, the Dunkirk PSB is the appropriate choice.
Does D's Air & Heating pull permits for boiler installations?
Yes. D's Air & Heating pulls all required City of Chicago permits for every boiler installation. Permit processing is included in the installation price.
What sizes is the WPSB Series 4 available in?
The WPSB Series 4 is available in 7 sizes from 75 MBH to 299 MBH input for natural gas, covering single-family homes through large multi-unit buildings. Propane (DP) models are also available.
Explore More Dunkirk & Boiler Resources
Compare models, schedule service, or browse our full boiler lineup.
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.
Steam Boiler Expertise — What Chicago Building Owners Should Know
How a Steam Heating System Works
A steam boiler heats water to 212°F, producing steam that rises naturally through supply pipes to cast-iron radiators throughout the building. As the steam gives up its heat, it condenses back to water and returns to the boiler by gravity. One-pipe systems use the same pipe for both steam supply and condensate return. Two-pipe systems use separate supply and return lines, allowing better control and zoning.
The Hartford Loop — Why It Matters
The Hartford Loop is a critical safety piping arrangement on steam boilers. It prevents the boiler from losing its water level if a return pipe develops a leak. Without a properly installed Hartford Loop, a pipe failure can drain the boiler dry, causing catastrophic damage. D's Air installs the Hartford Loop correctly on every steam boiler installation.
Steam Boiler Sizing — EDR Calculations
Steam boilers are sized by Equivalent Direct Radiation (EDR) — the total radiation capacity of all the radiators in the building. The boiler must be sized to match the connected radiation, not the building's heat loss. An oversized steam boiler causes water hammer, wet steam, and rapid cycling. D's Air measures EDR on every steam boiler installation.
Water Quality and Treatment
Steam boiler water quality directly affects system performance and longevity. Impurities cause foaming, which produces wet steam and water hammer. Proper pH balance prevents corrosion of the boiler sections and pipes. D's Air tests water quality and recommends treatment on every steam boiler installation and service call.
Common Steam System Problems
The most frequent steam system issues in Chicago buildings: water hammer (banging pipes — usually caused by wet steam, improper pitch, or failed steam traps), uneven heat between floors (failed vents or traps), boiler cycling on low water (LWCO trips — check water level and return lines), and radiators that won't heat (air-bound — replace the air vent).
What to Expect From Your D's Air Steam Boiler Service
System Assessment
We inspect the boiler, near-boiler piping, Hartford Loop, vents, traps, and radiators before recommending any work.
EDR Measurement
For new installations, we measure every radiator in the building to size the replacement boiler correctly.
Written Estimate
You receive a complete written estimate covering equipment, labor, piping, and permits before any work begins.
Installation
Our crew installs the new boiler with proper near-boiler piping, Hartford Loop, and all safety controls.
Startup & Testing
We fill the system, fire the boiler, verify steam pressure, check all vents and traps, and confirm heat to every radiator.
Customer Training
We explain how to check the water level, what the pressuretrol does, and what maintenance is needed annually.
D's Air Steam Boiler Standards — Every Installation
- EDR calculation — boiler sized to match connected radiation
- Hartford Loop installed per industry standard
- Near-boiler piping per manufacturer specifications
- Equalizer pipe properly sized and connected
- Low-water cutoff tested and verified
- Pressuretrol set to correct operating pressure (typically 0.5–2 PSI)
- All steam vents and traps inspected and replaced as needed
- Water quality tested — treatment recommended if needed
- Gas pressure test and combustion analysis at startup
- City of Chicago permit pulled on every installation
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.
Why Choose D's Air & Heating, Inc.
D's Air & Heating, Inc. has been providing professional boiler installation, replacement, repair, and maintenance services throughout Chicago since 2009. Founded by Darryl Q. Joyner Sr., D's Air & Heating has built a reputation for honest recommendations, quality workmanship, and professional customer service that Chicago homeowners trust.
Choosing the right contractor is just as important as choosing the right equipment. Unlike contractors who simply swap equipment and leave, D's Air & Heating focuses on complete system performance. Our experienced technicians evaluate your home's heating needs, inspect existing piping and venting, verify proper sizing, and ensure your new Dunkirk WPSB Series 4 is installed correctly for maximum efficiency and long-term reliability.
Every boiler installation includes proper load calculations, startup procedures, safety verification, and customer training so you understand your new system. We pull all required City of Chicago permits, handle disposal of your old equipment, and leave your mechanical room clean. Our technicians are experienced with Chicago's older housing stock — bungalows, two-flats, greystones — and understand the specific requirements of hot water radiator and baseboard systems.
D's Air & Heating operates without contracts and without gimmicks. We provide transparent, upfront pricing before any work begins. When you call for a free estimate, you receive an honest assessment of your heating needs and a clear price — no surprises, no hidden fees.
Ready for a New Dunkirk WPSB Boiler?
D's Air & Heating provides professional Dunkirk boiler installation throughout Chicago.