Case Study: 1957 Boiler-to-Forced-Air Conversion in Mission Park, Bellevue

This case study documents a substantial boiler-to-forced-air conversion project completed for a 1957 ranch home in Mission Park, Bellevue. The work involved removing a 1957 original cast iron sectional boiler and 14 cast iron radiators, then designing and installing complete forced-air ductwork plus matched system equipment (furnace + AC). The conversion was driven by the customer’s need for central air conditioning capability (the hydronic system provided no cooling) combined with the difficulty of retrofitting AC into a small ranch home without compromising the limited interior space available for either mini-split equipment or ductwork around hydronic distribution.

Customer Situation

The property is a 1957 ranch home in Mission Park neighborhood of Bellevue, 1,400 sq ft on a 7,500 sq ft lot, with detached one-car garage. The original construction had hydronic heating with 14 cast iron radiators distributed throughout the home; no AC had been added in subsequent decades. The customers (couple in their mid-30s with two young children ages 4 and 7) had purchased the home 2 years earlier and identified the lack of central AC as a major comfort limitation, particularly during summer heat with young children.

Equipment situation prompting conversion consideration:

• 1957 original Weil-McLain cast iron sectional boiler, 67 years old (remarkable longevity but substantially beyond useful life)
• 14 cast iron radiators throughout home, all original 1957 installations
• No central AC; previous owner had used window units
• Customers had used window units during first two summers but disliked aesthetic, noise, and operational burden
• Children’s bedrooms particularly difficult to cool with window units
• 1957 boiler approaching end-of-life replacement need anyway

Customer objectives:

• Central AC capability eliminating window unit dependency
• Modern efficient heating
• Even comfort throughout home including children’s bedrooms
• Long-term solution given 30+ years intended ownership

Conversion Approach Analysis

Consultation by Jess Sandoval (Install Lead, 11 years, Manual D specialty). Assessment considered multiple approaches:

Option Analysis

• Option A — Preserve hydronic + add mini-split for cooling: $14,800-$18,500 for three-zone mini-split, retain functional radiators. Issues: 67-year-old boiler needs replacement soon adding another $11,500-$15,500 in 1-3 years; total $25,000-$33,000+ over near-term; mini-split aesthetic intrusion in small home with limited wall space; complex two-system maintenance.
• Option B — Replace boiler + add mini-split for cooling: $26,000-$33,000 total for both projects done now; same aesthetic concerns; complex maintenance.
• Option C — Convert to forced-air with new ductwork: $24,800 total including ductwork addition, furnace, AC, removal of radiators and boiler. Single integrated system, cleaner aesthetic, simpler maintenance.

Customer selected Option C based on long-term ownership intent and preference for integrated single-system solution despite the substantial initial investment.

Ductwork Design Considerations

• Small ranch home with single-story plus partial basement provided substantial flexibility for ductwork routing
• Basement ceiling space available for main supply trunk and return air paths
• Wall furring required in two locations for vertical supply branches to specific rooms
• Floor supply registers (period-appropriate for 1957 mid-century home) selected matching architectural style
• Return air via floor-to-ceiling hallway grilles maintaining open feeling

Project Execution

Substantial 5-day conversion project given the scope of equipment removal, ductwork installation, and new system installation:

Day 1 (8 hours) — Boiler and radiator removal: water-side drainage, disassembly of cast iron sectional boiler in sections (substantial weight), removal of all 14 cast iron radiators (each substantial weight; coordination required for transport), removal of original piping, capping of original gas line.

Day 2 (10 hours, two-technician crew) — Ductwork installation in basement: main supply trunk fabrication and installation, branch ductwork to each room, return air trunk and grille locations, wall furring construction in two locations for vertical supply branches.

Day 3 (10 hours, two-technician crew) — Continued ductwork installation: floor register installation throughout home, return air register installation, ductwork insulation and sealing with mastic, system pressure testing for leak verification.

Day 4 (8 hours) — New furnace and AC installation: Lennox ML195 condensing furnace (60K Btu/hr right-sized based on Manual J), Lennox ML17XC1 16 SEER2 AC (2 ton matched to load), refrigerant line set, condensate management, electrical work, gas line connection, chimney liner installation for orphaned water heater.

Day 5 (4 hours) — System startup and commissioning, combustion analysis, refrigerant charging, performance verification, customer walkthrough including operation explanation, filter replacement instructions, thermostat operation, maintenance plan discussion.

Results

• Central AC capability — first time the 1957 home has had central air conditioning
• Modern high-efficiency heating — 95% AFUE condensing furnace vs prior 65-70% AFUE atmospheric boiler (estimated 33% gas consumption reduction)
• Whole-home comfort — even cooling distribution through all rooms including children’s bedrooms; no more window unit struggles
• Window unit elimination — aesthetic, noise, and operational burden eliminated
• Single integrated system — simpler maintenance than two-system alternatives
• Long-term solution — appropriate for customer’s intended 30+ year ownership
• Federal Section 25C tax credit — $600 (30% × $600 max furnace)
• OPPD rebate — $400 SEER2 16 qualifying

Pricing

Total project cost: $24,800

• Lennox ML195 condensing furnace (60K Btu): $3,800
• Lennox ML17XC1 AC (2 ton, 16 SEER2): $4,200
• Ductwork installation (substantial scope): $8,400
• Chimney liner installation: $1,485
• Sidewall venting penetration: $245
• Condensate pump and drainage: $215
• Standard programmable thermostat: $125
• Boiler and radiator removal (substantial weight + 14 radiators): $1,985
• Original piping removal and disposal: $385
• Wall furring construction (two locations): $885
• Installation labor (40 hours across 5 days, two-technician crew for days 2-3): $2,485
• Materials, supplies, registers, grilles: $585

Net cost after rebates and credits:

• Project cost: $24,800
• OPPD rebate: -$400
• Federal Section 25C tax credit: -$600
• Net cost: $23,800

Trade-Off Discussion: Why Conversion vs Preservation?

The decision to convert from hydronic to forced-air involves substantial trade-offs that we discussed openly with the customer:

What was lost in conversion:

• Radiant heat distribution (cast iron radiators provide gentle radiant warmth vs forced-air convection)
• Even thermal mass (massive radiators store heat producing very even temperatures over time)
• Quiet operation (no forced-air blower noise)
• Historical character (original cast iron radiators were architectural elements of mid-century home)

What was gained in conversion:

• Central AC capability (impossible with hydronic-only system)
• Modern equipment efficiency (95% AFUE vs ~65-70% on aging boiler)
• Single integrated system simpler to maintain
• Equipment matched to customer’s long-term needs

For homes with substantial historic character (pre-1930 properties), we typically advocate hydronic preservation. For mid-century ranch homes (1950s-1960s) without substantial architectural character, conversion to forced-air with AC is often appropriate when customer priorities favor integrated cooling.

Lessons from This Project

• Small mid-century ranch homes provide reasonable flexibility for ductwork addition with basement supply trunk and modest wall furring
• Boiler-to-forced-air conversion is substantial scope; multi-day timeline appropriate for proper execution
• Conversion economics improve when boiler replacement would be needed anyway, combining both projects into single integrated solution
• Customer priorities and intended ownership duration substantially affect appropriate equipment approach
• Two-technician crews appropriate for substantial demolition and ductwork installation phases
• Historic character considerations weigh against conversion for pre-1930 homes but less restrictively for mid-century properties

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Contact Omaha Heating and Air Conditioning

For Mission Park boiler-to-forced-air conversion, ductwork addition consultation, substantial mid-century home upgrade, or whole-home HVAC project planning, call our 24/7 line.

• Emergency Line (24/7): (402) 258-6703
• MUD Gas Emergency: 402-554-7777 (suspected gas leaks)
• 911: for CO detector alarms or fire/smoke situations
• Address: Lake Regency Building, 450 Regency Pkwy #370, Omaha, NE 68114
• Email: info@omahaheatingairconditioning.xyz
• City of Omaha Mechanical Contractor License: #MC-2014-08847
• EPA Section 608 Universal: #608U-2014-227841

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