Air ConditioningMarlborough, MACommercial

Commercial Rooftop Unit Installation

Project Overview

Commercial HVAC failures directly impact a building owner's bottom line — through repair costs, energy waste, and tenant dissatisfaction. This Marlborough office building was hemorrhaging money on emergency repairs while simultaneously losing tenants due to comfort issues. A proactive replacement was overdue.

We worked closely with the property management company to design a system that would solve both the reliability and the comfort problems. The new Carrier 48HC units were selected for their proven commercial track record, serviceability, and built-in economizer capability. By adding zone dampers and individual suite thermostats, we transformed a single-zone building into a multi-zone facility where each tenant controls their own environment.

The project was phased over two weekends — one unit per weekend — so the building never lost all HVAC capacity at once. Our team coordinated with a crane operator, electricians, and the roofing contractor to ensure a seamless installation that maintained the building's roof warranty.

The Challenge

A 15,000 square foot Marlborough office building housing multiple tenants was suffering from chronic HVAC failures. The existing rooftop units were 18 years old and well past their expected lifespan. Compressor failures occurred every few months, leading to emergency repair bills exceeding $15,000 annually. Temperature swings of 10–15°F between different office suites caused constant tenant complaints, and two tenants had threatened to break their leases. The building's energy costs were running $4,200/month for HVAC alone, far above the benchmark for a building of this size.

Our Solution

We removed both aging rooftop units using a crane and installed two new Carrier 48HC 10-ton packaged rooftop units with economizer sections. The economizers use free cooling from outside air when temperatures are moderate, significantly reducing compressor runtime during spring and fall. We also replaced all rooftop ductwork transitions and added motorized dampers to create four independently controlled zones within the building — allowing each tenant suite to maintain its own temperature setpoint. A new BACnet-compatible building management system provides the property manager with remote monitoring and scheduling capabilities. The entire project was completed over two weekends to minimize disruption to tenants.