Affton Closet Installation Relocation: 1971 Ranch Garage-to-Interior Move

Case study summary: 1971 slab-on-grade ranch home in Affton; existing 2003-vintage garage-mounted furnace and 2010-vintage AC due for replacement; customer decided to relocate equipment from garage to converted interior closet (small bedroom closet adjacent to existing supply trunk) during replacement; project required interior framing modifications, electrical relocation, gas line extension, supply trunk reconfiguration, and combustion air ducting; total project cost $18,400 vs. estimated $13,200 for garage-location replacement (relocation premium $5,200); completed in 4 days during November 2025. Outcome: garage space freed up for storage and workshop use; quieter equipment operation noticeable in living areas; full code compliance simpler with interior installation than garage; customer satisfaction high with garage space recovery despite higher initial cost.

The Home

• Built: 1971
• Style: Slab-on-grade ranch typical of early 1970s Affton subdivisions
• Location: Affton, MO 63123 (specific neighborhood near Heege Road)
• Size: 1,560 sf with attached two-car garage
• Construction: Slab-on-grade concrete foundation; wood frame with stone veneer; original aluminum windows replaced with vinyl in 2012
• Existing heating: Trane XR80 (60,000 BTU/hr 80% AFUE single-stage furnace from 2003, 22 years old at time of replacement); located in attached garage
• Existing cooling: Trane XR13 2-ton AC from 2010, paired with furnace
• Garage configuration: 22′ x 22′ two-car garage; furnace occupied approximately 24 square feet of floor space plus required clearances limiting garage usability
• Interior closet candidate: 3′ x 4′ bedroom closet adjacent to existing supply trunk wall; closet was currently used for general storage but could be converted to mechanical room

The Situation

Customer contacted us in September 2025 with end-of-service-life equipment and interest in relocation rather than direct garage replacement. Customer drivers:

• Garage usability: existing furnace plus required clearances occupied approximately 40-50 square feet of garage floor space, substantially limiting workshop use of garage; customer planned to use freed space for woodworking workshop
• Avoiding garage-installation premium: customer aware that garage replacement requires code-compliance scope additions (bollards, elevated platform, combustion-air seal, sealed combustion equipment) that increase replacement cost; relocation would avoid recurring garage scope for future replacements
• Quieter operation in home: garage-mounted equipment noise transmits through shared wall into adjacent bedrooms; interior closet location with proper sound isolation could reduce noise
• Existing closet utilization: customer identified bedroom closet currently used for general storage that could be repurposed for mechanical room with closet contents relocated
• Budget acceptance: customer accepted relocation cost premium ($5,200 over garage replacement) as worthwhile investment for garage space recovery

Initial feasibility assessment confirmed relocation was practical:

• Closet location adjacent to existing supply trunk would minimize ductwork reconfiguration scope
• Gas line extension from existing garage location through interior wall to closet was straightforward
• Electrical service relocation feasible with existing panel capacity
• Combustion air supply to closet feasible via exterior wall installation
• Condensate management via interior drain or condensate pump
• Closet space (3′ x 4′, 12 square feet) adequate for furnace with required service clearances per equipment specifications

The Equipment Selection

Carrier Performance 96 Modulating Furnace (Selected)

• AFUE: 96%
• Capacity: 60,000 BTU/hr input (Manual J calculation showed 48,000 BTU/hr design heating load; 60,000 BTU equipment provides appropriate margin)
• Technology: Modulating gas valve with variable-speed ECM blower; sealed combustion design
• Footprint: 21" wide x 28" deep x 35" tall — fits within 3′ x 4′ closet space with required 24" front service clearance
• Why selected: Modulating operation matches relatively small heating load for this home; sealed combustion appropriate for interior closet installation; Carrier brand consistency with replaced equipment manufacturer

Carrier 24ANB7 2.5-Ton AC (Selected, slight upsize)

• SEER2: 16.0
• Capacity: 2.5 tons (upgrade from previous 2 tons; Manual J showed 28,400 BTU/hr design cooling load)
• Refrigerant: R-454B
• Why upsize: previous 2-ton was undersized for actual load (caused extended runtimes during peak demand); modest upsize to 2.5-ton provides appropriate sizing margin

Alternative Equipment Considered

• Lennox EL296V 96% AFUE: alternative manufacturer with similar features; selected against based on Carrier dealer support continuity
• Direct garage replacement: this was the alternative to relocation (would have saved $5,200 but kept garage occupancy)

The Project Scope

Pre-Installation

• St. Louis County Public Works permit: Pulled within 5 business days; both mechanical and electrical permits required for relocation scope
• Equipment ordering: 10 business days for Carrier equipment
• Customer pre-installation work: customer cleared bedroom closet of stored items; relocated closet contents to garage temporarily

Installation Day 1 (November 4, 2025)

• Existing garage equipment isolation and shutdown
• Old furnace and AC removal: 8:30 AM – 11:30 AM
• Existing combustion air openings in garage exterior wall: customer wants to retain for future use possibilities; openings sealed with removable plugs for now (vs. permanent closing)
• Existing garage ductwork transition through wall to interior: capped with removable plate (preserving option for future garage equipment installation if home is sold to buyer wanting garage configuration)
• Bedroom closet preparation: existing closet doors removed; closet interior framing assessed for equipment installation; existing shelving and rod removed
• Closet framing modifications: door opening widened from 28" to 36" for equipment access (standard service requirement); installed louvered door for combustion air return; reinforced floor framing for equipment weight (60,000 BTU furnace plus AC indoor coil weighs approximately 250 lbs)
• Supply trunk modification: existing supply trunk in adjacent wall accessed from closet side; new connection point established for relocated equipment
• Return air ducting: new return air opening cut into closet interior wall with grille at hallway-facing location
• End of Day 1: closet framing complete, supply trunk modifications complete, equipment not yet installed

Installation Day 2 (November 5, 2025)

• Gas line extension: ran new black iron gas line from existing garage location through wall into closet space; routed inside wall cavity from garage side to closet floor; pressure tested per code
• Electrical relocation: existing electrical for garage furnace relocated; new dedicated circuit run from main panel to closet location for furnace and AC indoor coil; 240V circuit for outdoor unit retained at existing outdoor location
• Equipment placement in closet: furnace placed at floor level (no elevated platform needed for interior installation); AC indoor coil placed on top of furnace
• Sealed combustion intake/exhaust: dual PVC pipes routed from equipment through interior wall to exterior wall penetration; intake/exhaust termination on exterior of home
• Condensate management: condensate from AC coil and from condensing furnace combined drain to bathroom floor drain (closet adjacent to bathroom with available floor drain)
• Outdoor unit relocation: existing outdoor AC unit removed and new R-454B compatible 2.5-ton condenser installed on existing pad
• Refrigerant line set: new line set routed from outdoor unit through exterior wall to closet location (different routing than previous garage installation)
• End of Day 2: equipment installed but not commissioned

Installation Day 3 (November 6, 2025)

• Refrigerant system commissioning: nitrogen pressure test, vacuum pull to 500 microns or below, R-454B refrigerant charge
• Subcooling and superheat verification at outdoor unit
• Furnace commissioning: combustion analysis with Bacharach Fyrite Insight Plus (CO 14 ppm air-free, well under 100 ppm safety threshold; CO2 9.5%; O2 5.9%); modulating gas valve calibration
• System performance verification: heating mode and cooling mode operation verified; supply air temperature appropriate; even distribution across supply registers
• Closet door installation: louvered door installed for combustion air return path
• Noise verification: sound level measured at adjacent bedroom wall during equipment operation (47 dB at bedroom wall with closet door closed, compared to estimated 56-58 dB with garage installation; substantial improvement)
• Customer walk-through: explained operation, smart thermostat setup (basic programmable thermostat retained from previous installation), maintenance schedule, warranty registration
• Garage cleanup: removal of old equipment fragments, cleaning of garage floor where equipment had been located; customer’s reclaimed garage space verified

Installation Day 4 (November 7, 2025)

• Closet finishing: drywall patches at any wall modifications; closet interior paint matching to existing
• Closet door installation finishing: louvered door painted to match adjacent doors
• Garage finishing: removal of garage combustion air openings sealing (customer chose to permanently close openings rather than retain for future use); drywall patches and paint matching
• Final cleanup throughout home: removal of installation debris, vacuuming of installation areas, surface cleaning
• Customer final walk-through and sign-off

Inspection (November 12, 2025)

• St. Louis County DPW inspector visit 5 business days after installation
• Mechanical inspection: closet installation, sealed combustion configuration, ductwork modifications, gas line installation verified
• Electrical inspection: new circuits, panel modifications, equipment connections verified
• Installation passed both inspections without modifications

The Pricing

• Carrier Performance 96 60,000 BTU modulating furnace: $2,800 equipment
• Carrier 24ANB7 2.5-ton AC condenser and coil: $3,800 equipment
• Installation labor (4 days, 2 technicians): $6,800 (substantially higher than typical 2-day garage replacement labor reflecting relocation scope)
• Closet framing modifications (door widening, framing reinforcement, louvered door): $880
• Supply trunk modifications and return air ducting: $640
• Gas line extension and pressure testing: $480
• Electrical relocation and new circuits (mechanical permit + electrical permit): $980
• Sealed combustion PVC intake/exhaust installation: $440
• Condensate management routing to bathroom floor drain: $180
• Refrigerant line set new routing (vs. existing garage routing): $480
• St. Louis County DPW mechanical permit: $240
• St. Louis County DPW electrical permit: $140
• Old equipment removal and disposal (furnace + AC outdoor + AC indoor): $380
• Bacharach combustion analysis and commissioning: $240
• Sound testing and verification: $80
• Drywall, paint, and closet finishing work: $580
• Miscellaneous fittings, hardware, and consumables: $360
• Total project cost: $18,400

Relocation premium calculation: estimated garage replacement cost would have been approximately $13,200 (similar to the previous Affton garage replacement case study with comparable equipment). Relocation premium: $18,400 – $13,200 = $5,200 (approximately 39% over garage replacement). This premium covered the closet framing modifications, supply trunk reconfiguration, gas and electrical relocation, longer installation timeline, and finishing work to make the closet conversion clean and proper.

The Outcome

Garage Space Recovery

• Floor space freed: approximately 40-50 square feet recovered from equipment location plus clearance requirements
• Customer use: customer set up woodworking workshop in freed space within 2 weeks of installation completion; workshop includes table saw, workbench, tool storage, dust collection
• Garage condition: garage permanently transformed from equipment location to functional workspace; substantial quality of life improvement for customer who values woodworking

Noise Reduction

• Sound levels measured during commissioning: 47 dB at adjacent bedroom wall with closet door closed vs estimated 56-58 dB with previous garage installation
• Subjective comparison: customer reports equipment operation is now barely audible in living areas, whereas previous garage installation was clearly audible during equipment cycling
• Sound isolation benefits: louvered closet door allows combustion air movement while attenuating sound transmission; closet interior wall construction provides additional sound isolation vs. garage shared wall

Heating Performance

• First-winter operation (November 2025 – March 2026): System maintained setpoint reliably throughout heating season
• Modulating benefits: longer cycles at lower output provide better distribution than previous single-stage; customer reports more even temperatures throughout home

Code Compliance Simplification

• No garage-specific scope: interior installation eliminates need for bollards, elevated platform, garage-to-interior air seal verification, combustion air opening configuration
• Future replacements simpler: equipment replacement in 15-25 years will be standard interior installation rather than garage installation with recurring code-compliance scope
• Inspection process: interior installation inspection scope similar to basement installation rather than more complex garage inspection

Customer Feedback

Customer reported high satisfaction with several aspects: garage workshop space exceeded expectations and has been used substantially since installation; noise reduction in adjacent bedroom is dramatic improvement that wasn’t fully anticipated; closet conversion looks clean and professional rather than "jury-rigged"; ongoing operating cost lower than previous equipment despite slight AC upsize (efficiency improvement more than offsets capacity increase); confidence in current code compliance simpler than ongoing concern about grandfathered garage installation.

Ongoing Service

Customer enrolled in maintenance plan covering the new equipment; annual fall maintenance scheduled before heating season; first cooling-season verification scheduled for May 2026.

Frequently Asked Questions

Is relocation worth the $5,200 premium over direct garage replacement?

Depends on customer values and how garage space is used. For this customer who wanted dedicated woodworking workshop space, the value of 40-50 square feet of usable garage was substantial — woodworking workshop with table saw alone requires 8-foot working radius around the saw for safe operation, so the freed equipment space made the workshop layout practical. For other customers with different garage uses, the calculation varies: garages used purely for vehicle parking gain limited benefit from freed equipment space (vehicles fit in any 22’x22′ garage regardless of equipment location); garages used for general storage benefit modestly from freed space; garages used for workshop or activity space benefit substantially from freed space. Beyond direct space benefit, relocation provides ongoing benefits: future equipment replacements (15-25 years from now) will be standard interior installation without garage-specific scope premium ($1,200-$2,200 saved per future replacement); noise reduction is substantial quality-of-life improvement noticed daily; code compliance simpler over long term. For customers considering relocation: assess current garage use and projected future use; consider future home sale value (interior equipment installation more standard than garage installation and potentially more attractive to future buyers); calculate total cost of ownership including future replacement savings. This customer’s relocation premium ($5,200 one-time) divided by estimated 25-year equipment lifetime equals approximately $208/year amortized — modest annual cost for the substantial garage space and noise benefits gained.

What does it take to convert a closet into a mechanical room?

Specific framing and configuration requirements based on equipment specifications and code. Space requirements: equipment footprint plus required service clearances (typically 24 inches front clearance for furnace, 12-18 inches sides depending on equipment); minimum closet size approximately 30 inches deep by 36 inches wide for smallest equipment, more typically 36-48 inches deep by 36-60 inches wide for standard residential equipment; ceiling height adequate for vertical clearance above equipment (typically 8 feet adequate). Framing modifications: door opening widened to minimum 30 inches wide (36 inches in this case study) for equipment access; doorway typically requires louvered door for combustion air return path (homes with sealed combustion equipment may use standard solid door if return air ducted from elsewhere); floor framing assessment for equipment weight (60,000-100,000 BTU furnace plus AC indoor coil weighs 250-380 lbs depending on equipment); wall framing modifications for ductwork penetrations and supply/return connections. Code requirements: combustion air supply (sealed combustion equipment uses outdoor intake; non-sealed equipment requires specific opening configuration to provide adequate combustion air); combustion air return path from inside home (typically via louvered door or other opening providing air return to equipment area); fire-resistance considerations if closet adjacent to other rooms (typically 5/8 inch drywall on common walls); access to all sides of equipment requiring service (limited access reduces equipment service life and increases maintenance cost). Utility requirements: gas line extension to closet location; electrical service (typically 120V for furnace controls and 240V if AC indoor coil includes electric resistance backup); condensate drainage (gravity to drain or condensate pump to acceptable drain location); refrigerant line set routing to outdoor unit. Customer-side preparation: clearing closet of stored items; potentially relocating closet contents to other storage; aesthetic considerations for closet finish work. We assess closet conversion feasibility during initial quote consultation and provide explicit pricing for relocation scope vs. equipment-only replacement.

Could you have moved equipment to attic or basement instead of closet?

For this slab-on-grade home, no — neither was a practical option. Attic installation: most slab-on-grade ranch homes have limited attic access and limited attic clearance; attic installation requires substantial structural modifications for equipment support, equipment installation through limited access (attic stair or hatch); typically more expensive than closet conversion for similar capacity equipment; attic temperature extremes in summer (140°F+) and winter (subfreezing) reduce equipment efficiency and service life. Basement installation: not possible since this home is slab-on-grade construction (no basement). Other potential locations: dedicated mechanical room (would require new construction adding to home; very expensive); separate exterior shed or enclosure (uncommon for residential equipment in suburban setting); utility room if home has one (this home didn’t have dedicated utility room beyond laundry which lacked adequate space). The closet conversion was the practical option for this home. For homes with basements: basement installation is typically the easiest and least expensive location for HVAC equipment; basement mechanical rooms allow easy service access, adequate space for equipment plus accessories (water heater, water softener, etc.), and no impact on usable home space. For slab-on-grade homes (common in Affton and other 1960s-1970s subdivisions): equipment placement options are more limited; garage installation is the original solution in original construction; interior closet conversion is the relocation option; attic installation is occasionally used but adds complexity. This customer’s closet conversion was the appropriate solution for the home configuration.

Why did installation take 4 days instead of the 2 days for typical replacement?

Relocation scope substantially expands installation timeline. Standard 2-day garage replacement: Day 1 equipment removal and new equipment placement in same location with existing utilities; Day 2 commissioning and finishing work. Relocation 4-day scope: Day 1 equipment removal AND closet preparation framing modifications (door widening, framing reinforcement, supply trunk modifications, return air ducting); Day 2 utility relocation (gas line extension, electrical relocation) AND equipment placement in new location; Day 3 commissioning and outdoor unit replacement; Day 4 finishing work (drywall, paint, garage cleanup, closet finishing). The additional 2 days reflect: framing work that doesn’t exist in standard replacement (closet conversion to mechanical room); utility relocation work running through walls and floors (gas line, electrical, condensate, refrigerant) vs. simple reconnection at same location; longer commissioning time for systems with new utility connections; finishing work to make closet conversion look clean and professional. Customer-side impact: longer installation period required equipment heating to be provided through portable means during installation timeline (4 nights without operational heating in November); customer used electric space heaters in main living areas during installation period; family schedule adapted to installation crew presence over extended period. We typically schedule relocations during shoulder seasons (October-November or April-May) when temporary heating gaps are manageable; emergency relocations during peak heating or cooling season are more challenging due to need for temporary HVAC arrangements during installation timeline. Customer who scheduled this installation in November appropriately for shoulder season completion.

What happens if my closet is too small for the equipment?

Several options depending on specific situation. Smaller equipment: lower-capacity equipment has smaller footprint and might fit in tighter closet; this only works if the home’s heating/cooling load actually justifies smaller equipment (Manual J calculation determines minimum acceptable capacity; can’t simply downsize equipment to fit closet space if home needs larger capacity). Closet expansion: if adjacent space is available (adjacent room, hallway, etc.), closet could be expanded structurally to accommodate larger equipment; involves wall removal and reconfiguration, adds substantial cost; appropriate when other closet conversion option is clearly the right approach for the home. Alternative interior locations: utility room, mechanical room, basement (if available), large pantry, hallway nook with appropriate enclosure; each option has specific feasibility and cost considerations. Maintaining garage installation: if no acceptable interior location exists, garage installation may be the only practical option; this returns to standard garage scope with all the code compliance additions we discussed in the previous case study. Custom-fit equipment: some manufacturers offer narrower or shorter equipment for tight spaces; these typically cost more than standard equipment but may enable installation where standard equipment wouldn’t fit; trade-off between equipment cost premium and other relocation costs. Assessment process during quote consultation: we measure available closet spaces, identify equipment options that fit, calculate Manual J load to verify equipment capacity is appropriate, evaluate utility routing to closet location, and assess total scope cost vs. garage installation alternative. For some homes, closet conversion isn’t practical and garage installation is the right answer; for this customer’s home, the bedroom closet provided adequate space for appropriately-sized equipment, making conversion the better choice.

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Contact Purisync Heating and Air

For your garage-to-interior equipment relocation, closet conversion, or other HVAC equipment placement evaluation, contact our 325 N Kirkwood Road office at (314) 338-5111. Initial consultation includes assessment of current equipment location, evaluation of alternative interior installation locations, Manual J load calculation, equipment options that fit available spaces, and written quote with itemized pricing comparing relocation vs. equipment-only replacement.

• Emergency Line (24/7): (314) 338-5111
• Address: 325 N Kirkwood Rd #245, Kirkwood, MO 63122
• Email: info@purisyncheatingairconditioning.xyz
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