Commercial Rooftop Units — Rivic Heating & Air Conditioning

Packaged rooftop units (RTUs) are the dominant commercial HVAC configuration across Merrimack Valley small-to-mid commercial: 3-ton to 25-ton self-contained units mounted on the roof, containing compressor, condenser, evaporator, blower, gas heat or electric heat, controls, and outdoor air economizer in a single weatherproof cabinet, ducted down through the roof to serve the space below. RTU dominance in the Merrimack Valley commercial footprint is driven by installation efficiency (single roof-mount replaces separate outdoor condenser plus indoor air handler plus separate heating equipment), reduced indoor floor space demand (all mechanical equipment lives on the roof), simplified service access (roof-mount is directly accessible without disrupting occupied space), and cost efficiency in the small-to-mid capacity range.

Rivic services all major commercial RTU brands installed across Merrimack Valley small-to-mid commercial: Trane Voyager, Carrier WeatherMaker, Lennox Landmark and Energence, York Predator, Bryant Legacy, Daikin Rebel, Aaon RN Series. Service scope includes installation of new RTUs with crane coordination and roof penetration flashing, replacement of end-of-life RTUs with crane exchange, refrigerant service and repair, gas heat exchanger service, blower motor replacement, control board and thermostat integration, economizer damper service, curb repair and replacement, and coordinated commercial PM contract enrollment.

The RTU Anatomy: What’s Inside a Packaged Rooftop Unit

• Compressor: scroll compressor on modern units (Copeland scroll typical); reciprocating on older equipment; single-stage, two-stage, or variable-capacity depending on tier.
• Condenser coil: outdoor coil rejecting heat from the refrigerant to ambient air; copper-tube aluminum-fin standard, microchannel on some newer premium equipment.
• Condenser fan(s): single or multiple direct-drive fans moving air across the condenser coil; larger RTUs have multiple fans.
• Evaporator coil: indoor coil where refrigerant absorbs heat from return air.
• Blower assembly: belt-drive centrifugal blower on most commercial RTUs; direct-drive ECM/BPM on premium equipment; sized to CFM required by the duct system.
• Gas heat section: burner assembly, heat exchanger (aluminized steel or stainless steel), induced-draft or forced-draft combustion; sized to heat load requirements.
• Electric heat option: electric resistance heat strips as primary heat source (heat pump RTU) or as backup heat with gas primary.
• Outdoor air economizer: dampers and controls allowing outdoor air to be used for cooling when outdoor conditions are favorable; ASHRAE 90.1 requires economizer on commercial RTUs in Massachusetts climate zone.
• Filter rack: return air filter compartment; 2-inch to 4-inch pleated filters standard.
• Controls: microprocessor control board managing compressor staging, economizer operation, blower speed, and fault detection; communicates with commercial thermostat or building automation system.
• Curb: structural mounting adapter between the RTU cabinet and the roof, providing structural support, weather sealing, and duct connection through the roof.

Common RTU Configurations Rivic Installs

Gas Heat / Electric Cool (Dominant Configuration)

Natural gas heat section with electric AC cooling. Standard configuration for most Merrimack Valley commercial RTU applications where natural gas service is available. Advantages: fuel cost efficiency for heating, familiar operating characteristics, wide manufacturer availability. Common models: Trane Voyager YHC, YHD; Carrier WeatherMaker 48HC, 48TC; Lennox Landmark KGA/KHA; York Predator DM series.

All-Electric Cool with Electric Heat

Electric AC cooling with electric resistance heat as heating source. Common where natural gas service is not available at the property, in retrofit applications where extending gas service would exceed reasonable cost, or in applications targeted at heat pump conversion (electric-heat baseline that can be replaced with heat pump at a later capital cycle). Higher operating cost per BTU than gas heat but simpler mechanical configuration.

Heat Pump RTU (Increasing Merrimack Valley Adoption)

Reversible refrigerant cycle providing both cooling and heating with electric backup strips for periods when outdoor temperature exceeds heat pump capacity. Advantages: single-fuel-source operation (electric only), Mass Save Commercial rebate eligibility, IRA Section 179D eligibility. Trade-off: heating capacity degrades at low outdoor temperatures, backup electric strips run during design condition periods increasing operating cost during coldest weeks. Common models: Trane Voyager YHH, YSC heat pump variants; Carrier WeatherMaker 50TC heat pump; Lennox LZH heat pump packaged.

Dual-Fuel RTU (Gas Backup with Heat Pump)

Heat pump primary with gas heat backup engaged automatically at low outdoor temperatures. Balances the operating cost efficiency of heat pump most of the year with the reliability of gas heat during extreme cold. Uncommon in small commercial but appropriate for larger applications.

The Rivic RTU Installation Process

1. Site assessment: existing RTU condition and specifications, curb condition and structural integrity, roof condition and penetration status, mechanical space requirements, gas service capacity and pressure, electrical service capacity, building automation system integration requirements.
2. Load calculation: ACCA Manual N commercial cooling and heating load calculation against Lawrence Municipal Airport design conditions; ASHRAE 62.1 ventilation calculation per occupancy classification.
3. Equipment specification: capacity, staging (single-stage, two-stage, variable-capacity), efficiency rating (SEER2, EER, IEER for commercial equipment), economizer configuration, controls integration with existing building automation.
4. Written proposal: itemized equipment, installation labor, crane coordination, roof penetration and flashing coordination with roofer, controls and thermostat integration, commissioning, permit fees, coordination with utility for gas service if applicable, financing coordination.
5. Municipal permit filing: HIC-191847 for the HVAC scope, JGF-30521 for gas piping if applicable, coordination with building department for structural verification, in the affected 2018 Columbia Gas zone under 527 CMR 5.00 amended-code protocol for gas work.
6. Crane and staging coordination: crane sized to RTU weight and roof access constraints, staging area planning for temporary equipment placement, coordination with property manager or business for site access during installation window.
7. Roof coordination: existing curb condition verified or new curb specified and delivered; roof penetration flashing coordination with roofer to ensure warranty preservation on the roof; sequence coordination to minimize roof exposure during weather.
8. Removal of existing RTU if replacement: refrigerant recovery per EPA 40 CFR Part 82, disconnection of gas and electrical service, crane lift-off of existing unit for disposal or salvage.
9. New RTU installation: crane placement on curb, seismic and wind restraint per applicable code, gas piping connection and pressure test, electrical service connection and voltage verification, condensate drain routing, controls and thermostat wiring.
10. Commissioning: refrigerant charge verification, combustion analysis printout on gas equipment, capacity verification against design conditions, economizer operation verification, controls sequence verification, ventilation air measurement per ASHRAE 62.1, building automation integration verification.
11. Documentation and closeout: written commissioning report, manufacturer warranty registration, permit closeout, commercial PM contract enrollment (see commercial HVAC maintenance page).

Common RTU Service and Repair Scope

Cooling Season Common Issues

• Compressor short-cycling or failure (typical 12-18 year commercial service life).
• Contactor pitting and failure (typical 5-8 year commercial replacement interval).
• Capacitor failure (typical 8-12 year replacement interval).
• Condenser fan motor failure.
• Refrigerant leak requiring detection and repair.
• Refrigerant metering device (TXV or piston) failure.
• Evaporator coil freeze from restricted airflow (dirty filter, closed dampers, undersized returns).
• Condensate drain overflow and float switch trip.
• Economizer damper failure or stuck in wrong position (common cause of high summer energy consumption).

Heating Season Common Issues

• Ignition control failure (hot-surface igniter, spark ignition, direct spark).
• Gas valve failure.
• Pressure switch failure.
• Induced-draft motor failure.
• Flame sensor oxidation.
• Heat exchanger crack detection (Wohler flue camera borescope inspection on units over 10 years old).
• Combustion tuning to maintain ASHRAE 90.1 efficiency and low-CO emissions.
• Heat pump defrost cycle failure (heat pump RTUs).

Year-Round Common Issues

• Belt tension and drive alignment on belt-drive blowers.
• Blower motor bearing wear.
• Control board failure or firmware issues.
• Building automation system integration errors.
• Curb deterioration and roof leak development.
• Filter change and duct pressure management.
• Damper actuator failure (economizer, mixing dampers, zone dampers).
• Condensate line management (algae, freezing, overflow).

Curb Considerations (Merrimack Valley Specific)

RTU curbs age with the roof and often require attention during RTU replacement. Common Merrimack Valley scenarios: original curb from 1980s installation is undersized for modern replacement RTU footprint (older curbs designed for smaller compressor sections); original curb has developed structural rust from 40+ years of Merrimack Valley precipitation and freeze-thaw; original flashing has failed and roof leaks have developed around the curb; roof itself has been replaced with new membrane requiring new curb integration.

Rivic’s RTU replacement proposal explicitly addresses curb status: retain existing curb (if condition permits), install adapter curb over existing curb (if size mismatch), or install full replacement curb (if condition warrants). Adapter curbs range from $980 to $2,400 depending on size. Full curb replacement including roof coordination ranges from $2,400 to $5,800 depending on size and roof access. Ignoring curb condition during RTU replacement guarantees water damage within 5 to 10 years of the new RTU installation.

Economizer Compliance (Massachusetts Commercial Code)

ASHRAE 90.1 and Massachusetts Stretch Energy Code both require outdoor air economizer operation on commercial RTUs above specific capacity thresholds. Economizer uses cool outdoor air for cooling when outdoor conditions are favorable, reducing compressor operation and utility cost. Failed or improperly-configured economizers are one of the most common commercial HVAC energy-waste issues: economizer damper stuck open during winter (allowing cold air in and driving up heating cost), stuck closed during shoulder seasons (missing free cooling opportunities), or improperly commissioned control sequences.

Rivic’s commissioning process verifies economizer operation across all four modes: full economizer (outdoor air only for cooling), partial economizer (mixed outdoor and return air), minimum outdoor air (ventilation-only when outdoor conditions do not favor economizer cooling), and full recirculation (winter heating with minimum outdoor air per ASHRAE 62.1 ventilation requirement). Written commissioning report documents economizer verification for compliance documentation purposes.

Investment Ranges

• 3-ton to 5-ton gas/electric RTU installation with existing curb: $12,400 to $22,400 installed with crane and commissioning.
• 3-ton to 5-ton gas/electric RTU installation with new curb: $14,800 to $28,200 installed.
• 6-ton to 10-ton gas/electric RTU installation with existing curb: $18,000 to $34,000 installed.
• 6-ton to 10-ton gas/electric RTU installation with new curb: $22,000 to $38,000 installed.
• 10-ton to 15-ton commercial RTU installation with curb coordination: $28,000 to $58,000 installed.
• Heat pump RTU installation (add 15-25% to comparable gas/electric): $14,800 to $48,000 depending on capacity.
• Adapter curb (fit new RTU on existing curb of different size): $980 to $2,400.
• Full curb replacement: $2,400 to $5,800.
• Roof penetration and flashing coordination with roofer: $580 to $1,780 depending on scope (separate from RTU installation, roofer scope).
• Compressor replacement (existing RTU repair): $2,400 to $6,800 depending on compressor type and capacity.
• Gas valve replacement: $580 to $1,180.
• Blower motor replacement: $780 to $1,780.
• Belt and pulley service: $180 to $580.
• Economizer damper actuator replacement: $580 to $1,180.
• Control board replacement: $780 to $1,780.
• Emergency dispatch for RTU failure: $95 diagnostic + $185 after-hours surcharge (waived for PM contract customers) + repair scope.

Frequently Asked Questions

How long should a commercial RTU last?

Typical Merrimack Valley small-to-mid commercial RTU service life: 15 to 22 years with disciplined preventive maintenance. Compressor service life 12 to 18 years typical (variable depending on cycling patterns and refrigerant handling history). Blower motor 10 to 18 years. Heat exchanger 15 to 25 years. Control board 12 to 18 years. Economizer damper motors 8 to 15 years. Cabinet and structural components 20 to 30 years. Because different components have different service lives, RTUs typically undergo several component-level repairs during their overall service life before replacement is the correct economic answer. Rivic’s PM contract program identifies component-level replacement needs during routine service, allowing planned rather than emergency component replacement.

What triggers RTU replacement vs. continued repair?

Several economic thresholds. First: individual repair cost exceeding 40% of replacement cost typically favors replacement. Second: compressor failure on an RTU over 15 years old typically favors replacement (compressor replacement plus expected near-term additional repairs typically approaches replacement cost). Third: heat exchanger crack requires replacement (heat exchanger repair on commercial RTUs is not typically economical). Fourth: R-22 refrigerant systems (phased out 2020) increasingly favor replacement as R-22 availability declines and prices rise; matched R-454B replacement often more economical than continued R-22 service. Fifth: significant control system obsolescence where replacement parts are no longer available. Sixth: building operating priorities favoring lower utility cost (older single-stage RTUs replaced with modern two-stage or variable-capacity equipment for utility efficiency).

Can Rivic coordinate with our roofer during RTU replacement?

Yes, and Rivic strongly recommends this coordination. RTU replacement creates roof exposure at the curb penetration during the removal-and-replacement window; if the roof is aging or at end of service life, this is often the appropriate timing to coordinate roof work with RTU work. Common coordinated scopes: curb replacement including roof membrane integration, tapered insulation upgrade around the curb for water management, penetration flashing replacement with new membrane, or (in cases of severe roof condition) full roof section replacement coordinated with RTU replacement. Rivic works with several established Merrimack Valley commercial roofers and can facilitate the coordination if the customer does not have an established roofer relationship. Coordinated timing reduces total project cost vs. sequential work and reduces overall building disruption.

What are Massachusetts commercial RTU rebate opportunities?

Multiple layered programs. Mass Save Commercial and Industrial (C&I) high-efficiency equipment rebates typically $500 to $3,000 per ton depending on efficiency tier and equipment type. National Grid Commercial gas equipment rebates for gas heat sections meeting efficiency thresholds. Eversource Commercial electric equipment rebates for cooling and heat pump equipment meeting SEER2 and IEER thresholds. MassCEC Clean Heat program for commercial heat pump RTU installations. IRA Section 179D commercial energy efficiency tax deduction. Rebate stacking is possible where programs cover different aspects of the same installation; total rebate value on a compliant premium-efficiency installation can reach 20% to 35% of installed cost. Rivic’s proposal process coordinates with utility account representatives to identify all applicable rebates and files the paperwork through Kathleen Brennan.

How disruptive is RTU replacement to business operations?

Managed through timing. Standard 5-ton to 10-ton RTU replacement completes in 1 to 2 days on-site (existing RTU removal, curb work if needed, new RTU installation, commissioning). During those days, the space served by the RTU has no HVAC. Timing options: (a) shoulder-season timing (April/May or October/November) minimizes discomfort during the outage window, (b) after-hours or weekend timing keeps the business operational during business hours with the outage occurring overnight, or (c) temporary spot cooling or portable heating during the outage window if timing constraints require business-hours completion. Restaurants and medical practices typically require after-hours or shoulder-season timing to avoid revenue impact; retail can typically tolerate business-hours completion with temporary bridging if scheduled during shoulder seasons.

Contact Rivic Heating and Air Conditioning — RTU Service

Commercial rooftop unit service, replacement quotes, curb condition assessment, economizer commissioning, and PM contract enrollment route through the 225 Broadway office in central Methuen. Andrew Samples handles commercial RTU refrigeration scope; Marcus Devlin handles gas heat sections and gas piping coordination; Kathleen Brennan handles commercial rebate coordination and roofer scheduling.

• Emergency Line (24/7): (351) 240-2627
• Address: 225 Broadway #306, Methuen, MA 01844
• Email: info@rivicheatingairconditioning.xyz
• MA Refrigeration Technician License: #RT-24518
• MA Journeyman Gas Fitter: #JGF-30521
• MA Home Improvement Contractor: #HIC-191847
• EPA Section 608 Universal: #608U-2007-192874

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