West Valley City Commercial Warehouse Rooftop Replacement: 12-RTU Phased Project

Customer:

West Valley City commercial warehouse facility (consent given for documentation; facility manager handling project on behalf of property owner)

Address area:

West Valley City, near 3500 South and 5600 West — established industrial/warehouse district

Facility characteristics:

1998 commercial warehouse facility, approximately 78,000 sq ft single-story on slab. Mixed use: 64,000 sq ft warehouse storage, 14,000 sq ft attached office/showroom area. Concrete tilt-up construction with metal roof system. 28-foot ceiling height in warehouse, standard 10-foot ceilings in office area. 12 rooftop units originally installed during 1998 construction serving zones throughout the facility. Standard West Valley City commercial industrial property typical of the 5600 West corridor.

Project type:

Phased replacement of all 12 original 1998 Carrier 50TC rooftop units with new Carrier WeatherMaster commercial RTU equipment. Project scope included: equipment replacement, ductwork modifications where needed, controls upgrade, electrical work, commissioning, refrigerant handling, and crane services for equipment placement.

Project completion timeline:

14-week phased project — July 8 to October 11, 2024. Two RTUs replaced per week (Monday-Wednesday RTU swap, Thursday-Friday commissioning and next-RTU preparation). Phasing maintained facility operations throughout project.

Total cost:

$186,400 total project cost ($15,533 average per RTU). Net cost after Rocky Mountain Power Wattsmart commercial rebates ($28,800 total): $157,600.

Background

This West Valley City warehouse facility has been operated by the same family business since 1998. The original 12 Carrier 50TC RTUs were aging beyond expected service life (26 years at start of project). Multiple service issues had accumulated over 2022-2024: refrigerant leaks (R-22 system at end of refrigerant availability), capacitor failures, contactor wear, heat exchanger oxidation. The facility manager had been managing reactively with our prior service relationship but recognized that comprehensive replacement was needed before catastrophic failures during peak operating conditions. Property owner approved capital project. We were engaged in spring 2024 to plan and execute the phased replacement, coordinating with facility operations to maintain business continuity throughout the multi-month project.

Existing Equipment (12 RTUs Replaced)

Warehouse zone RTUs (8 units):

• 1998 Carrier 50TC 10-ton package units (model 50TC*A14)
• Gas heating + R-22 AC
• Single-stage operation
• Atmospheric venting through dedicated B-vent stacks
• Located on roof above respective warehouse zones
• 26 years service at time of replacement

Office area RTUs (4 units):

• 1998 Carrier 50TC 6-ton package units (model 50TC*A07)
• Same vintage, same configuration as warehouse units
• Serving office, showroom, conference room, and customer service areas
• Continued operation through cooler temperatures than warehouse zones (set point typically 72°F vs. warehouse 68-75°F)

Controls:

Original 1998 standalone commercial thermostats per zone. No building automation system. Each RTU operated independently with local thermostat. Manual zone setpoint adjustments by facility manager.

Refrigerant:

All 12 RTUs were R-22 systems. R-22 phase-out completed 2020 per EPA Section 608. Existing inventory available but expensive ($120-160/lb). Continuing R-22 system operation increasingly economically unfavorable.

Ductwork:

Original 1998 commercial sheet metal ductwork. Generally in good condition. Minor modifications needed during equipment replacement for new RTU footprint differences. Most ductwork retained without replacement.

Pre-Project Assessment and Planning (March-June 2024)

Initial facility assessment (March 2024):

Marcus Halverson and Dakota Whitfield performed comprehensive assessment of all 12 RTUs over 2-day visit. Per-unit evaluation: refrigerant pressures, combustion analysis (gas heating side), electrical components, structural condition, control board functionality, ductwork condition.

Per-RTU condition findings:

• RTU-1 to RTU-4 (warehouse east zones): Aging but functional. Recent capacitor and contactor replacements. R-22 charge issues identified on RTU-2 and RTU-3.
• RTU-5 to RTU-8 (warehouse west zones): Worse condition. Heat exchanger oxidation on RTU-6 (visible but no cracks confirmed). Cooling capacity degraded on RTU-7 (refrigerant leak history). RTU-8 control board intermittent issues.
• RTU-9 to RTU-12 (office zones): Better condition due to less demanding operating environment. Capacitor and contactor near end-of-life on RTU-10 and RTU-11.
• Overall: All 12 RTUs at or beyond expected service life. Continuing reactive repair pattern would cost $35,000-$55,000 annually in emergency repairs and operational inefficiency.

Equipment selection:

Carrier WeatherMaster commercial RTU platform selected. Reasoning: (a) same manufacturer as existing equipment (familiar parts, similar dimensions), (b) commercial-grade durability for industrial application, (c) energy efficiency exceeds 2021 IECC commercial requirements, (d) qualifies for Rocky Mountain Power Wattsmart commercial rebates, (e) Carrier’s commercial product line has extensive parts availability and contractor familiarity.

Standardized RTU selection:

All 12 RTUs replaced with standardized Carrier WeatherMaster 50FC platform:

• Warehouse zones (8 RTUs): Carrier 50FC*A14 (10-ton, gas heat + R-410A AC)
• Office zones (4 RTUs): Carrier 50FC*A07 (6-ton, gas heat + R-410A AC)
• Standardization simplifies: parts inventory, technician familiarity, control configuration, future service patterns

Manual J commercial load calculation verification:

Manual J performed for warehouse vs. office zones. Confirmed existing RTU sizing (10-ton warehouse, 6-ton office) appropriate for current building configuration. No equipment up-sizing or down-sizing recommended; replacement-in-place with same capacity.

Phasing decision:

14-week phased schedule developed. Two RTUs per week replacement pattern:

• Week 1: RTU-12 (office) + RTU-11 (office) — start with smaller, lower-risk units to refine procedures
• Weeks 2-4: Office zones complete (RTU-9, RTU-10 + warehouse zone RTUs)
• Weeks 5-12: Warehouse zones (RTU-1 through RTU-8)
• Weeks 13-14: Final commissioning, controls integration, building-wide verification

Phasing maintained facility operation throughout project. Each RTU replacement temporarily shuts down its specific zone (1-3 days), affecting only one of 12 zones at any time.

Crane services planning:

RTU lifts required crane services. 10-ton RTUs at ~1,200 lbs each, 6-ton RTUs at ~900 lbs each. Crane service coordinated for each replacement: 14-week period required 14 crane visits (one per replacement). Crane partner: Wasatch Front Crane (commercial crane operator with industrial site experience). Crane mobilization cost: $385 per visit (negotiated bulk rate vs. typical $585 per visit).

Equipment Specifications (Carrier WeatherMaster 50FC)

10-ton units (8 RTUs — warehouse zones):

• Model: 50FC*A14 (10-ton nominal, 120,000 BTU/hr gas heat, R-410A AC)
• Two-stage gas heat operation
• Two-stage scroll compressors
• Variable-speed indoor fan motor (commercial-grade ECM)
• Standard atmospheric venting
• R-410A refrigerant (factory charge)
• 10-year parts warranty (commercial unit warranty)
• 5-year compressor warranty
• Commercial-grade cabinet (heavy gauge steel, weather-resistant powder coat)

6-ton units (4 RTUs — office zones):

• Model: 50FC*A07 (6-ton nominal, 80,000 BTU/hr gas heat, R-410A AC)
• Two-stage gas heat operation
• Two-stage scroll compressors
• Variable-speed indoor fan motor
• Same warranty and construction as 10-ton units

Controls:

Honeywell T7800 commercial programmable thermostats (12 units, one per zone). Standard commercial 7-day programming with multiple daily setpoint events. Compatible with future building automation system upgrade (deferred for this phase).

Refrigerant:

R-410A factory charge. New R-410A required at each installation (lineset retained from original installation but flushed for R-22 to R-410A compatibility).

Electrical:

Existing 480V 3-phase service adequate for new RTU equipment. New outdoor disconnects (60A 480V 3-pole) per RTU.

Installation Procedures (Per-RTU Pattern)

Day 1 (Monday) — Old RTU removal:

• 7:00 AM: Dakota Whitfield + Marcus Halverson + crane operator arrived. Zone shutoff per facility manager coordination.
• 7:30 AM: R-22 refrigerant reclamation per EPA Section 608. Typical 10-ton unit charge: ~22 lbs. Reclaimed quantity recorded.
• 9:30 AM: Refrigerant lines disconnected. Electrical disconnected. Gas supply shut off and capped.
• 10:30 AM: Crane lift coordination. Roof-level crew prepared lifting straps. Old RTU lifted off curb and lowered to ground level for disposal.
• 11:30 AM: Lunch break.
• 12:15 PM: Roof curb inspection. Existing curb retained where possible (matching new RTU footprint where compatible) or modified for new RTU dimensions.
• 1:30 PM: Refrigerant lineset flush per R-22 to R-410A compatibility procedure. Nitrogen + R-410A-compatible flushing solvent.
• 3:00 PM: Roof curb modifications complete (if needed). End of Day 1.

Day 2 (Tuesday) — New RTU placement and connections:

• 7:00 AM: Crane operator + crew on-site. New RTU delivery confirmed.
• 7:30 AM: New RTU lifted to roof and placed on curb. Mounting and weather-sealing completed.
• 9:00 AM: Refrigerant line connections (brazing of pre-flushed lineset to new RTU coil).
• 10:30 AM: Electrical connections. Outdoor disconnect installation. 60A 480V 3-pole disconnect mounted at RTU.
• 11:30 AM: Gas supply connection. Manometer pressure verification.
• 12:30 PM: Lunch break.
• 1:15 PM: System pressure test (300 PSI nitrogen for 30 minutes). Refrigerant lineset and new RTU verified leak-free.
• 2:45 PM: System evacuation (24-hour deep vacuum — left running overnight to Day 3 verification).
• 5:00 PM: End of Day 2.

Day 3 (Wednesday) — Commissioning and verification:

• 8:00 AM: Vacuum verification (verified under 250 microns).
• 8:30 AM: R-410A refrigerant charge by weight per manufacturer specification.
• 9:30 AM: Honeywell T7800 thermostat installation in zone served by this RTU.
• 10:30 AM: System startup. Operational verification across heating and cooling modes.
• 11:30 AM: Combustion analysis (Testo 320 for commercial). CO verification, manifold pressure verification.
• 12:30 PM: Lunch break.
• 1:15 PM: Refrigerant charge verification. Subcooling and superheat measurements.
• 2:30 PM: Operational testing across full cooling and heating cycles.
• 3:30 PM: Zone returned to active facility operation. Facility manager briefed on RTU operation.
• 4:30 PM: End of Day 3. RTU replacement complete; next RTU preparation begins Thursday-Friday.

Thursday-Friday (Days 4-5) — Preparation for next replacement:

• Crane scheduling coordination for following week
• Next RTU delivery scheduling
• Materials staging
• Facility operations coordination for next zone shutdown
• Permit documentation for replaced RTU

Permits:

West Valley City Building Department commercial mechanical permits (one per RTU replacement): permits #WVC-2024-08247-1 through #WVC-2024-08247-12. Each permit covered: equipment specifications, refrigerant handling, gas connection verification, electrical work, commissioning.

Commissioning Standards (Per-RTU)

Refrigerant verification (per RTU):

• R-410A charge by weight per manufacturer specification (10-ton units: ~12 lbs; 6-ton units: ~9 lbs)
• Subcooling: 8-12°F (Carrier specification range)
• Superheat: 8-12°F
• Supply air temperature differential: 18-22°F (cooling mode at 75°F outdoor)
• Operating pressures within Carrier manufacturer specifications for design temperature

Combustion verification (per RTU):

• CO at flue: under 50 ppm (commercial requirement; well below acute exposure thresholds)
• O₂ in flue gas: 6-9%
• Steady-state efficiency: 80%+ (commercial standard for 80%+ AFUE-equivalent rating)
• Manifold pressure: 3.4″ WC (altitude-adjusted from nameplate 3.5″ WC)

Operational testing (per RTU):

• Full cooling cycle operation
• Full heating cycle operation
• First-stage and second-stage compressor operation
• First-stage and second-stage gas heat operation
• Defrost cycle verification (where applicable)

Final building-wide verification (Week 14):

After all 12 RTUs replaced, comprehensive building-wide verification: all RTUs operating simultaneously during a single business day, total facility cooling and heating demand met at design conditions, no zone-to-zone interference or short-cycling.

Cost Breakdown

Per-RTU pricing (10-ton warehouse units):

• Carrier 50FC*A14 equipment: $7,800
• R-410A refrigerant (12 lbs at $35/lb): $420
• R-22 reclamation (22 lbs per EPA Section 608): $385
• Lineset flush procedure: $245
• Roof curb modification (where needed): $245
• Crane services (lift and placement): $385
• Electrical work (new disconnect + connections): $385
• Gas connection and leak testing: $185
• Honeywell T7800 thermostat: $145
• Installation labor (3-day procedure, multi-tech crew): $2,400
• Commissioning (refrigerant verification, combustion analysis, operational testing): $385
• Permit fee: $245
• Subtotal per 10-ton RTU: $13,225

Per-RTU pricing (6-ton office units):

• Carrier 50FC*A07 equipment: $5,400
• R-410A refrigerant (9 lbs at $35/lb): $315
• R-22 reclamation (17 lbs per EPA Section 608): $285
• Other items (same as 10-ton): same costs
• Subtotal per 6-ton RTU: $10,355

Project total:

• 8 × 10-ton RTUs: $13,225 × 8 = $105,800
• 4 × 6-ton RTUs: $10,355 × 4 = $41,420
• Multi-RTU project overhead (12 permits, coordination, crane bulk scheduling): $14,000
• Building-wide commissioning week (Week 14): $25,180
• Project subtotal: $186,400

Rebates and incentives:

• Rocky Mountain Power Wattsmart commercial rebates (per RTU): $2,400 per 10-ton + $1,800 per 6-ton
• Total rebates: $2,400 × 8 + $1,800 × 4 = $19,200 + $7,200 = $26,400
• Rocky Mountain Power custom commercial efficiency rebate (additional): $2,400 for documented kWh reduction
• Total rebates: $28,800

Net project cost:

$186,400 – $28,800 = $157,600 net project cost

Comparison: Reactive maintenance economics

Continuing reactive maintenance pattern on 12 aging RTUs would have produced:

• Annual emergency repair cost (estimated): $35,000-$55,000
• Operational inefficiency cost (estimated additional electric + gas): $18,000-25,000 annually vs. new equipment
• Combined annual cost of continuing reactive pattern: $53,000-$80,000
• 3-5 year reactive cost: $159,000-$400,000

Net replacement cost ($157,600) recovered within 2-3 years of reactive maintenance avoidance. Plus: equipment life extension, reduced facility downtime, modern R-410A refrigerant economics, improved environmental performance.

Federal IRA 25C for commercial:

Not applicable to commercial property. Federal IRA 25C residential energy efficiency tax credit applies to personal residences only. Commercial tax incentives (Section 179, bonus depreciation) handled separately by property owner’s tax professional.

Post-Project Outcomes

Operational verification (October 11, 2024 project completion):

All 12 RTUs operating at design specifications. Building-wide commissioning verified: total facility cooling capacity adequate for peak summer demand, heating capacity adequate for design winter conditions, no zone-to-zone interference, refrigerant charges intact across all units.

Winter 2024-2025 operation (first heating season with new equipment):

• All 12 RTUs operating normally throughout heating season
• No emergency dispatches throughout winter (vs. 6-8 typical emergency dispatches per previous winter with old equipment)
• Gas consumption: estimated 22% reduction vs. prior year (improved efficiency from new equipment)
• Electric consumption: estimated 18% reduction vs. prior year (improved equipment efficiency + variable-speed motors)
• Combined utility cost savings: estimated $32,400 reduction vs. prior year operating cost

Summer 2025 cooling season operation:

• All 12 RTUs operating at design specifications throughout summer
• No service issues during peak demand periods
• Facility temperature setpoints maintained reliably across all zones
• R-410A operating efficiency notably better than legacy R-22 system

Facility manager assessment:

“The phased project approach was essential. We couldn’t have shut down operations for a single large project; the 2 RTU per week schedule kept the rest of the facility operating throughout. The new equipment is significantly more reliable than the 1998 units. Our maintenance budget for the past year has been dramatically lower than the previous several years.”

Service relationship continuation:

Commercial maintenance plan continued for all 12 new RTUs at $400 per RTU annual = $4,800 annual maintenance contract. Plan covers: bi-annual tune-ups (spring + fall) for each RTU, priority dispatch for any emergency issues, 15% discount on repair parts and labor, full service history documentation.

Why This Case Study Illustrates Important Patterns

Phased commercial replacement methodology:

Commercial facilities can’t shut down operations for major HVAC replacement. Phased approach allows: facility operations continuity, manageable workload for installation crew, ability to refine procedures across multiple units, customer cash flow management across project duration. Phasing pattern (2 RTUs per week with 5-day cycle) provides predictable rhythm for both installer and facility.

R-22 phase-out commercial economics:

R-22 commercial systems past 20 years of service face economic decision: continue R-22 maintenance ($120-160/lb refrigerant when leaks occur) or replace with R-410A. For multi-unit commercial facilities, the economic case for replacement is strong: refrigerant cost differential alone justifies replacement over remaining service life. Energy efficiency improvements add to the case. This 12-RTU facility documented $32,400+ first-year savings; multi-year savings recover capital project cost within 5-7 years.

Equipment standardization across multi-unit projects:

Standardizing equipment across all 12 RTUs (Carrier WeatherMaster 50FC platform) provides: simplified parts inventory for future service, technician familiarity, control configuration consistency, predictable maintenance patterns. Trade-off: equipment may be slightly oversized or undersized for specific zones. Manual J verified existing sizing was appropriate; standardization decision was straightforward.

Rocky Mountain Power Wattsmart commercial rebates:

Commercial Wattsmart rebates significantly reduce capital project cost. $26,400 in standard rebates + $2,400 custom efficiency rebate = $28,800 total reduction (15.4% of project cost). Rebates require: equipment meeting efficiency standards, pre-installation application, post-installation verification documentation. Coordinating rebate applications during project planning maximizes available incentives.

Crane services coordination:

Multi-RTU projects require crane services scheduling. Bulk crane mobilization rates (negotiated $385/visit vs. typical $585/visit individual rates) reduce per-RTU cost by $200+ per unit. Coordination of crane availability with replacement schedule essential; crane availability bottlenecks can delay entire project. Established relationships with commercial crane operators valuable for production multi-RTU projects.

Commercial maintenance plan post-installation value:

Annual maintenance plan ($4,800 for 12 RTUs) provides ongoing service continuity. Bi-annual tune-ups catch developing issues across all 12 units before failures. 15% discount on repair parts and labor reduces ongoing maintenance costs. Service history documentation supports manufacturer warranty claims and future capital planning. For commercial facilities with multi-unit HVAC, maintenance plans are strongly recommended.

Code and Standards Compliance Documentation

Applicable codes and standards:

• 2024 IMC with Utah amendments: Commercial mechanical equipment installation
• IFGC Section 304.1: Altitude derate at West Valley City 4,200 ft elevation (16.8% derate)
• UMC Section 510: Combustion air provision (commercial atmospheric venting verified)
• ACCA Manual J: Commercial heat and cooling load calculation
• ACCA Manual S: Commercial equipment selection
• ASHRAE 90.1: Commercial building energy efficiency standards
• 2021 IECC commercial provisions: Energy efficiency requirements
• NEC Article 440: Commercial air-conditioning equipment
• EPA Section 608: R-22 reclamation and R-410A handling (lead technician certified)
• Utah DOPL HVAC contractor licensing: #11567823-5501 active and current
• Rocky Mountain Power Wattsmart commercial program requirements: Equipment specifications and documentation

Permits issued (one per RTU):

West Valley City Building Department commercial mechanical permits #WVC-2024-08247-1 through #WVC-2024-08247-12

Inspections passed:

All 12 commercial mechanical inspections passed (sequential as each RTU completed). Inspector verified: equipment specifications match permit, refrigerant handling per EPA Section 608, combustion safety verification, electrical work, gas pressure verification, commissioning measurements.

Documentation maintained:

Manual J calculations, Manual S selections, R-22 reclamation logs (EPA Section 608), refrigerant charge documentation, commissioning measurements per RTU, Wattsmart rebate applications, warranty registrations.

Frequently Asked Questions

Why replace all 12 RTUs at once instead of one at a time as they fail?

Economic and operational analysis favored coordinated replacement. Continuing reactive replacement pattern would have: (a) cost $35,000-55,000 annually in emergency repairs, (b) created unpredictable facility downtime as units failed, (c) maintained mixed R-22/R-410A inventory complexity, (d) prolonged exposure to expensive R-22 refrigerant. Coordinated phased replacement: predictable schedule, business operations continuity, simplified post-project maintenance, modern refrigerant economics, energy efficiency improvements. Net cost recovery within 2-3 years of avoided reactive costs.

How did you maintain facility operations during the project?

2 RTUs per week phasing pattern. Each individual RTU replacement requires zone shutdown for 3 days (Monday-Wednesday) but only affects that specific zone. Of 12 zones, 11 remain operational at any time during the 14-week project. Facility manager coordinated zone shutdowns with operations: scheduled the RTU servicing those zones during lower-activity periods, ensured warehouse staff and office workers had information about temporary zone shutdowns.

What rebates are available for commercial HVAC replacement?

Rocky Mountain Power Wattsmart commercial rebates: $2,400 per 10-ton RTU + $1,800 per 6-ton RTU at meeting efficiency standards. Custom efficiency rebates available for documented kWh reductions. Application process: pre-install qualification, post-install verification documentation. This project recovered $28,800 total rebates (15.4% of project cost). Rebate availability and amounts vary by program year; check current Wattsmart program details.

Can other commercial HVAC manufacturers achieve same efficiency?

Yes. Carrier WeatherMaster competes with: Trane Voyager, Lennox Energence, York Sunline, Daikin Maverick, Goodman GPC commercial. All major commercial HVAC manufacturers produce similar quality and efficiency tiers. Selection factors: equipment dimensions matching existing roof curbs, manufacturer service network in Wasatch Front, parts availability, contractor familiarity. Our standardization on Carrier WeatherMaster reflects: existing equipment was Carrier (familiar dimensions), contractor familiarity, parts availability in Salt Lake County distribution network.

How long should commercial RTUs last?

Typical commercial RTU service life: 20-25 years with proper maintenance. Heavy commercial use (24/7 operation, high-cycling environments): 15-20 years. Light commercial use (single-shift operation, moderate climate): 22-30 years. This facility’s 1998 equipment was replaced at 26 years — at upper end of typical service life. New Carrier WeatherMaster equipment with maintenance plan should provide 20-25 years service. Replacement decisions during normal service life require: condition assessment, efficiency analysis vs. modern equipment, refrigerant economics, expected remaining service life.

Project Details Summary

Customer:

West Valley City commercial warehouse facility, family-owned business operating since 1998

Facility:

78,000 sq ft warehouse/office facility, 12 original 1998 Carrier 50TC RTUs at end of service life

Project type:

Phased replacement of all 12 RTUs with new Carrier WeatherMaster 50FC platform

Completion timeline:

14-week phased project (July 8 – October 11, 2024); 2 RTUs per week pattern with facility operations continuity

Equipment installed:

8 Carrier 50FC*A14 (10-ton warehouse RTUs) + 4 Carrier 50FC*A07 (6-ton office RTUs) + Honeywell T7800 commercial thermostats

Total cost:

$186,400 total; $28,800 in Rocky Mountain Power Wattsmart rebates; $157,600 net project cost

Outcome:

All 12 RTUs operating at design specifications. 22% gas consumption reduction + 18% electric consumption reduction first year (combined $32,400 utility savings). Zero emergency dispatches winter 2024-2025 (vs. 6-8 typical previous winters). Capital project cost recovery projected 5-7 years from utility savings + maintenance cost avoidance.

Service relationship:

Commercial maintenance plan continued at $4,800 annual for all 12 RTUs. Bi-annual tune-ups, priority dispatch, 15% repair discount. Service history documentation supports warranty and capital planning.

Schedule Commercial HVAC Replacement Consultation

• Phone: (385) 300-1867
• Address: 756 E Winchester St #322, Salt Lake City, UT 84107
• Email: info@saltlakecityheatingairconditioning.xyz
• Utah DOPL HVAC Contractor License: #11567823-5501
• EPA Section 608 Universal (Lead Tech): #608U-2009-447129

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