Case Study: Restaurant RTU Replacement on East Hartford Main Street
This case study documents a 2024-2025 commercial HVAC replacement at a 4,500 square foot restaurant on East Hartford's Main Street commercial corridor. Restaurant HVAC is distinct from other commercial property types: kitchen hood exhaust creates substantial makeup air requirements; cooking heat generates significant internal load; dining-area comfort affects customer experience and tip economics; operating schedule constrains installation timing. This case study demonstrates restaurant-specific HVAC considerations including hood makeup air coordination, scheduling around restaurant operations, and balancing comfort across kitchen and dining areas.
Customer Situation
The restaurant owner operates a casual dining establishment serving lunch and dinner Tuesday through Sunday:
- Existing equipment: 1996 Carrier 48GS 12-ton packaged rooftop unit; 28 years old; R-22 refrigerant; multiple emergency calls during 2022-2024 with rising frequency.
- Kitchen hood system: Type I commercial hood (10 feet wide) over cooking equipment; 4,200 CFM exhaust; original 1996 installation with subsequent service; required makeup air not adequately addressed in original design.
- Building characteristics: Brick masonry construction from 1923 (original commercial building); restaurant in current configuration since 1988 conversion; substantial windows along Main Street facade; metal roof with multiple HVAC and exhaust penetrations.
- Operating schedule: Tuesday-Saturday 11 AM-10 PM; Sunday 11 AM-9 PM; closed Mondays; substantial weekend dinner demand; kitchen operating substantially longer than dining service hours.
- Comfort concerns: Tenant comfort complaints during peak service hours; kitchen heat substantially affecting dining area temperatures; uneven temperature distribution; humidity control during summer challenging.
- Customer priorities: Eliminate refrigerant supply concerns (R-22 phase-out); improve makeup air coordination with kitchen hood; better comfort balance between kitchen and dining areas; reliable operation supporting restaurant business continuity.
- Service history: Annual maintenance plan customer since 2019; familiar property; rising R-22 service costs.
Diagnostic Visit and Restaurant-Specific Engineering
September 2024 commercial diagnostic and engineering consultation:
- Existing equipment condition: 1996 Carrier RTU at 28 years; well past commercial service life; R-22 refrigerant pressures showed substantial capacity loss; combustion analysis indicated declining efficiency.
- Manual N restaurant load calculation: Combined building cooling load 145,000 BTU/hr (12.1 tons) including kitchen heat gain from cooking equipment; combined heating load 178,000 BTU/hr at Hartford 4°F winter design; existing 12-ton equipment appropriately sized for cooling but undersized for heating.
- Kitchen heat gain assessment: Cooking equipment, oven, range, fryer, broiler produce approximately 35,000 BTU/hr of internal heat gain during peak operation; this load substantial component of total cooling requirement.
- Hood makeup air analysis: 4,200 CFM hood exhaust requires equivalent makeup air; existing system inadequate (typically 75-80% of exhaust); produces negative pressure during hood operation, drawing outside air through gaps in building envelope (uncontrolled, unconditioned).
- Refrigerant transition: R-22 phase-out driving replacement timing; R-454B (new commercial standard) selected for replacement equipment.
- Building structural assessment: Existing roof curb adequate for replacement equipment; some structural reinforcement needed for slightly larger equipment.
- Engineering recommendation: Replace RTU with right-sized equipment (15-ton to handle heating load adequately); add dedicated makeup air unit for hood operation; integrate hood exhaust control with main HVAC system.
Solution Scope and Equipment Selection
Primary HVAC Equipment
- Trane Voyager 3 light commercial RTU: 15-ton (180,000 BTU/hr) cooling; 240,000 BTU/hr gas heating; SEER2 14.5, EER 11.5, 81% AFUE; R-454B refrigerant. Selected for: right-sized for restaurant loads including kitchen heat gain, adequate heating capacity, reliable warranty support.
- Integrated economizer with kitchen interaction logic: Outdoor air dampers coordinated with hood operation; when hood is operating, economizer logic adjusts to provide makeup air balance.
- Demand control ventilation: CO2 sensors in dining areas; adjusts outdoor air based on occupancy; meets Connecticut commercial code.
- MERV 11 filtration: Higher-grade filtration than typical commercial standard; appropriate for restaurant indoor air quality.
- Two-stage gas heating: Modulates capacity 65-100%; better match for variable restaurant load.
Makeup Air Unit
- Dedicated makeup air unit (MAU): Greenheck MUA-1 3,200 CFM makeup air unit dedicated to hood makeup air; integrates with hood control panel; activates automatically when hood operating.
- Tempered makeup air: MAU includes gas-fired heating section for cold weather; pre-heats incoming makeup air to prevent kitchen comfort issues during winter.
- MAU placement: Located on roof adjacent to RTU; coordinated with hood exhaust to prevent re-entrainment.
- Hood integration: MAU operation linked to hood fan; automatic activation; reduces uncontrolled air infiltration during hood operation.
Building Automation
- Restaurant-specific control programming: HVAC scheduling matches restaurant operations; kitchen ventilation coordinated with hood; dining area comfort prioritized during service hours.
- Remote monitoring: Building owner receives equipment alerts; restaurant manager has thermostat access; tenant comfort tracking.
Installation Process
Project completed November 2024 over weekend plus Monday closure day to minimize restaurant disruption:
Saturday Late Night — Equipment Removal
- 11:00 PM Saturday: Restaurant closes for evening; equipment shutdown for installation work.
- 11:30 PM Saturday: Crane mobilization; old Carrier RTU removal preparation.
- Midnight Saturday — 3:00 AM Sunday: Old RTU removal; refrigerant recovery per EPA Section 608; electrical disconnection; curb assessment and preparation.
Sunday — Primary Equipment Installation
- 7:00 AM Sunday: Crane mobilization for new equipment.
- 8:00 AM — 1:00 PM: New Trane Voyager RTU positioning; structural reinforcement of curb; electrical connections; refrigerant lineset connections.
- 1:00 PM — 6:00 PM: Makeup air unit installation; hood control integration; ductwork connections from MAU to kitchen makeup air supply.
Monday (Restaurant Closed) — System Commissioning
- 9:00 AM Monday: Refrigerant system charging; pressure testing for leaks.
- 10:00 AM — 2:00 PM: Full system commissioning per ASHRAE Standard 90.1.
- 2:00 PM — 5:00 PM: Demand control ventilation calibration; building automation integration; restaurant-specific control programming.
- 5:00 PM Monday: Final operational verification; equipment ready for Tuesday opening.
Tuesday Morning — Restaurant Verification
- 10:00 AM Tuesday: Restaurant manager verification before opening; brief walkthrough; thermostat training.
- 11:00 AM Tuesday: Restaurant opens normally; comfort verified during service.
Results
System operating since November 2024. Results documented through 2024-2025 winter and 2025 summer operations:
- Operating cost reduction: Combined annual HVAC cost $9,800 (vs. $14,800 previous year); 34% reduction.
- Comfort improvement: Customer comfort complaints eliminated; dining area temperature stable during peak service hours; kitchen comfort improved with proper makeup air balance.
- Kitchen environment: Makeup air unit eliminates uncontrolled negative pressure; comfort and air quality substantially better for kitchen staff.
- Operational reliability: No HVAC-related restaurant downtime since installation; reliable through 2024-2025 winter and 2025 summer.
- Humidity control: Improved dehumidification during summer; less condensation on cold beverage glassware.
- Acoustic improvement: Quieter outdoor unit operation; less noise impact on Main Street adjacent properties.
- R-454B refrigerant security: Long-term refrigerant supply security; no concerns about future service availability.
Investment Summary
- Trane Voyager 3 15-ton commercial RTU: $22,400
- Greenheck MUA-1 3,200 CFM makeup air unit: $14,800
- Economizer, DCV, MERV 11 filtration: $4,400
- Hood control integration and electrical interlock: $2,400
- Refrigerant recovery, line modifications, materials: $3,200
- Crane mobilization (single weekend visit): $4,200
- Structural curb reinforcement: $1,840
- Electrical work (disconnect upgrades, MAU wiring): $4,400
- Ductwork connections from MAU to kitchen: $3,200
- Installation labor (3-day weekend, 4 technicians): $12,800
- Commissioning per ASHRAE 90.1: $1,840
- Building automation integration and restaurant programming: $2,400
- Permits, EPA Section 608, inspection: $640
- Total project cost: $78,560
- Eversource commercial rebate (restaurant tier with MAU bonus): −$5,600
- Federal IRA 179D commercial deduction: Applied to building owner's tax return; estimated $6,400 reduction in federal tax liability over multi-year deduction period.
- Net effective customer investment: $72,960 (after Eversource rebate, pre-tax deduction)
Long-Term Economics
- Annual energy savings: Approximately $5,000 (combined heating, cooling, and ventilation efficiency) based on first-year data.
- Reduced maintenance: New equipment under warranty; substantially less repair activity vs. aging R-22 equipment.
- Restaurant operational value: Reduced HVAC downtime risk; avoided restaurant closure days from equipment failures; value substantially exceeds direct energy savings.
- Simple payback period: Approximately 14-15 years on net investment.
- Equipment lifespan: 15-20 years for properly maintained restaurant RTU; substantial value capture beyond payback period.
Lessons Applicable to Other Restaurant Properties
- Restaurant HVAC requires kitchen-specific engineering: Hood exhaust drives makeup air requirements; cooking equipment adds substantial internal heat gain; ductwork integration with hood system important.
- Makeup air units often missing in older restaurants: Many 1990s and earlier restaurant installations lack dedicated makeup air; uncontrolled negative pressure during hood operation common; modernization opportunity.
- Operating schedule constrains installation timing: Restaurant installations typically require complete weekend shutdown or Monday closure; advance scheduling essential.
- Customer comfort directly affects business economics: Restaurant comfort affects dining experience, average ticket size, and customer return rate; HVAC investment supports business performance.
- Kitchen staff comfort affects retention: Properly tempered makeup air improves kitchen working conditions; reduces staff turnover and training costs.
- R-22 phase-out forcing manufacturer-customer timing: Many 1990s restaurant installations facing similar R-22 replacement timing; supply chain pressures.
- Building automation valuable for restaurant operations: Restaurant-specific control programming optimizes for operating schedule; remote monitoring prevents emergency issues.
Frequently Asked Questions
- How is restaurant HVAC different from other commercial properties?
- Several substantial differences. (1) Kitchen heat gain: cooking equipment, oven, range, fryer produce substantial internal heat gain (25,000-50,000+ BTU/hr typical); included in sizing calculations. (2) Hood exhaust requirements: Type I commercial hoods exhaust 3,000-6,000+ CFM during operation; requires equivalent makeup air. (3) Makeup air systems: dedicated makeup air units (MAUs) often required; provides tempered makeup air to balance hood exhaust; prevents uncontrolled negative pressure. (4) Indoor air quality requirements: restaurant code requirements specify minimum ventilation; some require dedicated grease-laden air handling. (5) Comfort variation: dining areas and kitchen areas have substantially different comfort requirements; sometimes separate zones. (6) Operating hours: restaurant operations often extend beyond office hours; HVAC sized for extended operation. (7) Occupancy variation: substantial occupancy variation through day (lunch rush, dinner rush, off-peak); demand control ventilation valuable. (8) Equipment reliability: HVAC downtime directly affects restaurant operations; reliability investment justified. (9) Acoustic considerations: dining customers prefer quiet HVAC; balance against equipment performance.
- What is a makeup air unit (MAU) and why is it needed?
- A makeup air unit (MAU) is dedicated HVAC equipment that provides outdoor air to replace air exhausted by kitchen hoods. Specifically: (1) Function: when kitchen hood operates and exhausts air to outdoors, that air must be replaced; without MAU, building develops negative pressure pulling outdoor air through gaps in envelope. (2) Capacity: sized to match hood exhaust capacity (typically 75-95% of exhaust rate); for 4,200 CFM hood, MAU sized 3,200-4,000 CFM. (3) Tempering: MAU includes heating section (gas-fired typically) and sometimes cooling section; heats/cools makeup air before delivery to kitchen. (4) Distribution: MAU delivers makeup air to kitchen area via dedicated ductwork; often integrates with or near hood for direct replacement of exhausted air. (5) Hood interlock: MAU operation linked to hood fan; activates automatically; deactivates when hood stops. (6) Code requirements: Connecticut commercial code requires makeup air for substantial commercial hood installations. (7) Comfort impact: properly tempered makeup air prevents cold drafts in winter; provides reasonable air quality. (8) Without MAU: uncontrolled negative pressure causes cold drafts through doors and windows; reduces dining comfort; increases heating costs. The MAU addresses what would otherwise be uncontrolled and uncomfortable air infiltration.
- What's the typical timeline for restaurant HVAC installation?
- Variable based on scope but typically requires complete restaurant closure. Common timelines: (1) Single RTU replacement without makeup air: 2-3 days; weekend installation typical. (2) RTU plus makeup air unit (this case study): 3-5 days; weekend plus Monday closure typical. (3) Complete restaurant HVAC overhaul: 5-10 days; sometimes extended closure during off-season. (4) New restaurant build-out HVAC: 3-7 days within larger construction timeline. (5) Emergency restaurant repair: same-day to 3 days depending on parts availability. Scheduling considerations: (1) Restaurant operations: typically Tuesday or Wednesday closure day for many restaurants; weekend installation common. (2) Seasonal timing: off-season installations (typically January-February in Hartford area) when restaurant volume lower. (3) Equipment delivery: 1-3 weeks typical for commercial equipment; advance ordering essential. (4) Permit coordination: 2-4 weeks for commercial permit approval in some municipalities. (5) Holiday avoidance: avoid major holidays when restaurant volume highest. (6) Tenant coordination: if multi-tenant property, coordination with other tenants.
- How does R-22 phase-out affect restaurant equipment replacement timing?
- R-22 phase-out is producing substantial pressure for older restaurant equipment replacement. Timeline and considerations: (1) Production phase-out: R-22 production substantially restricted since 2010; complete phase-out 2020. (2) Service supply: existing R-22 supplies available but increasingly scarce; pricing $300-$800 per pound vs. R-454B $100-$200. (3) Equipment service costs: R-22 service calls increasingly expensive; sometimes economical to replace rather than service. (4) Refrigerant leaks: R-22 system leaks expensive to address; replacement often economically appropriate. (5) Restaurant equipment age: many 1990s restaurant installations still operating with R-22; substantial replacement market. (6) New equipment: R-454B (HFO refrigerant blend) replacing R-22 in commercial equipment; long-term supply security. (7) Decision factors for replacement: equipment age (15-20+ years), refrigerant capacity loss, increasing service costs, restaurant business growth or change. (8) Economic considerations: refrigerant alone often $1,500-$4,000 for substantial R-22 charge; replacement equipment cost includes new refrigerant. (9) Customer trajectory: many restaurant owners ready for replacement as R-22 service costs increase year-over-year.
- What rebates and incentives apply to restaurant HVAC projects?
- Several programs help restaurant owners with substantial HVAC investments. (1) Eversource commercial rebates: tiered by efficiency level; restaurant tier sometimes has specific incentives; high-efficiency tier $4,800-$6,400+ typical for moderate scope. (2) Eversource makeup air unit rebates: dedicated MAU equipment often qualifies for separate rebate. (3) Federal IRA 179D commercial deduction: tax deduction up to $5/sq ft for projects meeting efficiency standards; depreciation acceleration over multi-year period. (4) Federal IRA 48 investment tax credit: applies to some renewable energy components (solar thermal); typically not applicable to standard restaurant equipment. (5) Connecticut state programs: some additional state-level programs available for high-efficiency commercial. (6) Utility energy management programs: ongoing operational programs may provide demand response or energy management incentives. (7) Specific applicability: depends on project scope, equipment selection, and restaurant operating profile. For this case study, combined Eversource rebate plus 179D deduction reduced effective project cost by approximately $12,000; substantial impact on capital allocation decision.
Contact Biozura Heating and Air
For restaurant and commercial HVAC consultation in East Hartford and surrounding areas, contact us. Specialized commercial coordination and weekend installation scheduling available. Connecticut DCP Unlimited HVAC License #S1-0414829.
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