Case Study: Light Industrial Rooftop Unit Replacement in New Britain
This case study documents a 2024 commercial HVAC replacement for an 8,400 square foot light industrial facility in New Britain's south manufacturing district. New Britain's industrial heritage from Stanley Works, Fafnir Bearing, and other manufacturing legacy produced substantial light industrial real estate that continues serving manufacturing, distribution, and fabrication tenants. This project demonstrates light industrial HVAC distinct from retail or office: process heat loads, manufacturing tenant requirements, and after-hours installation coordination.
Customer Situation
The building owner operates a precision machining business occupying the 8,400 square foot building:
- Existing equipment: Two 1994 Lennox LGA Series packaged rooftop units (10-ton and 12-ton nominal cooling); both R-22; both 30+ years old.
- Building use: Light industrial machining operation; CNC equipment producing internal heat gain; precision manufacturing requiring stable temperature and humidity for measurement accuracy.
- Operating hours: Two-shift operation (Monday-Friday 7 AM to 11 PM); HVAC required during business hours; weekend production rare.
- Service history: Annual maintenance via previous contractor; multiple emergency calls in 2023-2024 with both units; R-22 refrigerant supply increasingly expensive; obvious replacement timing.
- Comfort and process priorities: Maintain consistent 68-72°F during operations for both worker comfort and measurement equipment accuracy; humidity control 40-55% range; dust filtration important for precision machining environment.
- Building characteristics: 1985 construction; reasonable envelope efficiency for the era; concrete tilt-up walls with metal roof; substantial fluorescent lighting load.
Diagnostic Visit and Engineering
September 2024 commercial diagnostic visit assessed equipment and identified replacement requirements:
- Equipment condition: Both 1994 RTUs at 30 years; well past commercial HVAC typical service life (15-20 years); refrigerant pressures indicated 40-55% capacity loss vs. original specifications; heat exchanger inspection on both showed crack development requiring shutdown.
- Manual N commercial load calculation: Combined building cooling load 158,000 BTU/hr (13.2 tons) including process heat gain from CNC machinery; combined heating load 195,000 BTU/hr at Hartford 4°F winter design.
- Refrigerant transition: R-22 service supply diminishing; R-454B (new commercial standard) for replacement equipment; mandatory transition driving replacement timing for many similar properties.
- Building structural assessment: Existing roof curbs sized for original equipment; structural support adequate for replacement units of similar or slightly different size.
- Electrical service: 480V 3-phase service adequate; existing disconnect and wiring appropriately sized.
- Indoor air quality requirements: Precision machining environment requires good filtration (MERV 11+) for measurement accuracy and equipment protection; existing system marginal; replacement opportunity for improvement.
- Ductwork assessment: Original ductwork generally adequate; some sections required cleaning and sealing during installation.
Solution Scope and Equipment Selection
Equipment Selected
- Two Trane Voyager Light Commercial RTUs:
- Primary unit: 15-ton 180,000 BTU/hr cooling, 240,000 BTU/hr gas heating; SEER2 14.5, EER 11.8, 81% AFUE.
- Secondary unit (smaller building section): 7.5-ton 90,000 BTU/hr cooling, 120,000 BTU/hr gas heating; SEER2 14.0, EER 11.5.
- Combined capacity 22.5-ton; replaces 22-ton original equipment with slight right-sizing improvement.
- Integrated economizers on both units: Outdoor air dampers modulating between minimum ventilation and 100% outdoor air; required by Connecticut commercial code; provides free cooling during shoulder seasons; substantial energy savings.
- Demand control ventilation: CO2 sensors in shop floor and office areas; adjusts outdoor air based on occupancy levels; coordinates ventilation across both RTUs.
- MERV 11 filtration: Higher-grade filtration than typical commercial standard; improves dust capture for precision machining environment; reduces dust accumulation on measurement equipment.
- Trane commercial thermostats: Programmable schedule for two-shift operation; weekend setback settings; vacation override for plant shutdown periods.
- Building automation integration: Both units integrated with central building automation platform; remote monitoring; fault alerts; performance tracking.
- Connectivity: Cellular communication module for remote access; no dependence on facility network infrastructure.
- Acoustic enclosures: Sound-attenuating enclosures on outdoor compressors; reduces noise impact on adjacent commercial properties.
Installation Process
Project completed November 2024 over weekend (Friday evening through Monday morning) to minimize manufacturing disruption:
Friday Evening — Setup and Equipment Removal
- 4:00 PM Friday: Last shift ends; equipment shutdown for installation work.
- 5:00 PM: Crane mobilization; first unit (smaller) removal preparation.
- 5:30 PM — 9:30 PM: First unit removal; refrigerant recovery per EPA Section 608; electrical disconnection; curb assessment and preparation.
- 10:00 PM: First replacement unit positioned but final connections deferred to Saturday morning.
Saturday — Primary Equipment Installation
- 7:00 AM: Crane returns; second (larger) unit removal preparation.
- 7:30 AM — 11:30 AM: Second unit removal; refrigerant recovery; electrical disconnection.
- 12:00 PM: Second replacement unit positioning.
- 1:00 PM — 6:00 PM: Both units electrical connections; refrigerant lineset connections; pressure testing for leak verification; system charging.
Sunday — Commissioning and Testing
- Both units system fill and pressure verification.
- Commissioning per ASHRAE Standard 90.1: airflow verification at all supply diffusers; static pressure measurement; refrigerant superheat and subcool verification; combustion analysis for gas heating; economizer operation verification across outdoor temperature ranges.
- Demand control ventilation calibration: CO2 sensor verification; ventilation minimum and maximum settings configured.
- Building automation integration: connectivity verification; alert configuration; remote monitoring access provisioning.
- 5:00 PM Sunday: Final system verification complete; ready for Monday operations.
Monday Morning — Startup Verification
- 6:30 AM Monday: Building startup before first shift; system verified operating across all zones.
- 7:00 AM: First shift arrival; comfort verified during morning operations.
- 30-day comfort guarantee: any issues during first 30 days addressed under installation warranty.
Results
System operating since November 2024. Documented results through 2024-2025 winter and 2025 summer operations:
- Energy cost reduction: Combined 2024-2025 HVAC operating cost (heating + cooling) estimated $8,400 vs. $12,800 previous year equivalent period; 34% total reduction.
- Manufacturing operations: No HVAC-related production disruption since installation; reliable operation through 2024-2025 winter and 2025 summer.
- Precision machining environment: Temperature stability improved (±2°F vs. previous ±5°F variation); humidity control improved with modern equipment; dust levels reduced from improved MERV 11 filtration.
- Worker comfort: Two-shift operation comfort improved; comfort complaints reduced to zero from previous occasional reports.
- Demand control ventilation impact: Tracking data shows ventilation reduction during second-shift hours (lower occupancy); estimated $1,200 annual savings from DCV across both units.
- Remote monitoring value: Building owner receives equipment alerts; proactive service coordination; no surprise breakdowns since installation.
- R-454B refrigerant: No refrigerant losses; system charge stable; long-term refrigerant supply security.
Investment Summary
- Trane Voyager 15-ton + 7.5-ton commercial RTUs: $31,400
- Integrated economizers, DCV, MERV 11 filtration: $4,800
- Crane mobilization and roof access (weekend rate): $4,200
- Refrigerant recovery, line modifications, materials: $2,840
- Electrical work (disconnect upgrades, code updates): $3,200
- Installation labor (weekend, 3 days, 4 technicians plus crane operator): $11,800
- Commissioning per ASHRAE 90.1: $1,640
- Building automation integration: $2,400
- Acoustic enclosures (compressors): $1,840
- Permit, inspection, EPA Section 608 documentation: $640
- Total project cost: $64,800
- Eversource commercial rebate (high-efficiency tier): −$4,800
- Federal IRA 179D commercial energy efficiency deduction: Applied to building owner's tax return; estimated $5,600 reduction in federal tax liability over multi-year deduction period.
- Net effective customer investment: $54,400 (after Eversource rebate, pre-tax deduction)
Long-Term Economics
- Annual energy savings: Approximately $4,400 ($2,800 cooling + $800 heating + $800 DCV-specific) based on first-year data.
- Reduced maintenance costs: New equipment under warranty; substantially less repair activity vs. aging R-22 equipment.
- Simple payback period: Approximately 12-13 years on net investment.
- Manufacturing reliability value: Avoided manufacturing downtime; manufacturing tenant's production costs from HVAC downtime significantly exceed HVAC equipment savings.
- Equipment lifespan: 15-20 years for properly maintained commercial RTUs; 5-8 years of operational savings beyond payback period.
Lessons Applicable to Other Light Industrial Properties
- Process heat load matters in industrial sizing: CNC machinery, welding equipment, and other manufacturing produces substantial internal heat gain; commercial sizing calculation must include process loads in addition to envelope loads.
- Higher filtration standards justified for precision manufacturing: MERV 11+ filtration protects measurement equipment and improves precision machining quality; modest cost premium produces substantial operational benefit.
- Two-shift operation affects scheduling: Longer operating hours mean shorter weekly downtime windows for maintenance; coordinate around production schedules.
- Acoustic considerations for industrial properties: Outdoor compressor noise impact on adjacent commercial properties; sound-attenuating enclosures sometimes justified, particularly for facilities in mixed-use districts.
- R-22 phase-out forcing manufacturer-customer timing: Many similar 1990s-2000s industrial properties facing similar R-22 replacement timing; supply chain pressures.
- Building automation valuable for industrial: Remote monitoring particularly valuable for industrial properties where unplanned downtime affects production schedules and customer commitments.
- Right-sizing benefit substantial in industrial: Original equipment in many properties is oversized; right-sized replacement provides better humidity control and efficiency.
Frequently Asked Questions
- How does light industrial HVAC differ from retail or office?
- Several substantial differences. (1) Process loads: light industrial includes substantial internal heat gain from manufacturing equipment, machinery, welding, lighting; sizing calculations include these process loads in addition to envelope loads. (2) Operating hours: light industrial often operates extended hours (10-16 hour shifts vs. typical retail 10-12 hour days); HVAC sized for sustained operation. (3) Air quality requirements: manufacturing environments often require higher filtration (dust capture for precision work) and sometimes specific exhaust requirements. (4) Temperature stability: precision manufacturing requires tighter temperature tolerances than typical office or retail. (5) Equipment capacity: industrial facilities often have larger capacity equipment (15-25+ tons) than typical retail or office equivalents. (6) Maintenance scheduling: extended operating hours mean shorter weekly downtime; weekend or holiday maintenance often required. (7) Reliability emphasis: HVAC downtime affects manufacturing operations directly; reliability investment justified by avoided production losses.
- What's the typical light industrial HVAC project timeline?
- Variable based on building size, equipment capacity, and tenant requirements. Common timelines: (1) Single small RTU replacement (5-7 ton): 2-3 days, often single weekend. (2) Single larger RTU replacement (10-15 ton): 2-4 days. (3) Multiple RTU replacement (this case study's two-unit scope): 3-5 days; weekend installation common to minimize disruption. (4) Major retrofit including ductwork, controls, and equipment upgrades: 5-15 days. (5) New construction or major addition: 15-45 days. (6) Scheduling considerations: light industrial operations often allow weekend installation; some tenants require specific scheduling due to production commitments; advance notice essential. This case study's 3-day weekend timeline typical for moderate-scope two-unit installation.
- How is HVAC commissioning different for commercial vs. residential?
- Commercial commissioning per ASHRAE Standard 90.1 is more rigorous than typical residential service. (1) Airflow verification: measured at every supply diffuser to verify design airflow; substantial labor for multi-zone systems. (2) Static pressure measurement: verifies ductwork performance and equipment match. (3) Refrigerant verification: superheat and subcool measurements verify proper refrigerant charge; documentation required. (4) Combustion analysis: detailed measurement of combustion parameters for gas heating equipment; documentation per Connecticut commercial code. (5) Economizer operation: verified across outdoor temperature ranges; minimum and maximum positions verified. (6) Demand control ventilation: CO2 sensor calibration, ventilation rate verification at different occupancy levels. (7) Building automation: integration testing; communication verification; alert configuration. (8) Documentation: comprehensive commissioning report; required for some commercial code compliance. (9) Final acceptance: building owner sign-off on equipment performance verification. Total commissioning labor for this case study's scope was 8-12 hours; substantially more thorough than residential service patterns.
- What are common light industrial HVAC efficiency improvements?
- Several strategies produce substantial savings. (1) Equipment efficiency upgrades: replacing 1990s-2000s equipment with current efficiency standards typically produces 20-40% efficiency improvement. (2) Right-sizing: many older industrial facilities have oversized equipment; right-sizing improves efficiency, dehumidification, and reduces short-cycling. (3) Economizers: required by current code; provides free cooling during shoulder seasons. (4) Demand control ventilation: substantial savings during low-occupancy periods (second-shift, weekend). (5) High-efficiency filtration: MERV 11+ filtration improves indoor air quality with modest energy cost increase. (6) Building automation: scheduling and monitoring optimizations sometimes produce 5-10% additional savings beyond equipment efficiency alone. (7) Acoustic improvements: not energy-related but operational quality improvement for mixed-use districts. (8) Refrigerant transition: R-22 to R-454B; smaller refrigerant charges sometimes available with newer equipment. The diagnostic visit identifies which improvements fit specific facility needs and budget.
- What rebates and tax incentives apply to commercial HVAC projects?
- Several programs reduce effective cost. (1) Eversource commercial rebates: tiered by efficiency level; high-efficiency tier provides substantial rebate ($2,400-$8,400+ for typical commercial RTU); eligibility based on equipment efficiency and project scope. (2) Federal IRA 179D deduction: commercial building energy efficiency tax deduction; up to $5/sq ft for projects meeting efficiency standards; depreciation acceleration over multi-year period. (3) Federal IRA 48 investment tax credit: applies to some renewable energy components (geothermal, solar thermal); typically not applicable to standard commercial RTU. (4) Connecticut state programs: some additional state-level programs available for high-efficiency commercial projects. (5) Utility energy management programs: ongoing operational programs may provide demand response or energy management incentives. Specific applicability depends on project scope, equipment selection, and tenant lease structure. For this case study, combined Eversource rebate plus 179D deduction reduced effective project cost by approximately $10,400; substantial impact on capital allocation decision.
Contact Biozura Heating and Air
For commercial HVAC replacement projects in light industrial facilities, contact us for consultation. Specialized commercial coordination and weekend installation scheduling available. Connecticut DCP Unlimited HVAC License #S1-0414829.
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- EPA Section 608 Universal: #608U-2008-381467 (Joshua Scruggs), #608U-2009-512784 (Marcus Petrowski), #608U-2010-447831 (Tomás Reyes)
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