ROOFTOP UNITS
Commercial rooftop unit replacement
REPLACE OR REUSE
Replacing rooftop units without disrupting the building
A rooftop unit is the single biggest piece of HVAC equipment on most tenant improvements. Replacing one involves the roof, a crane, the structure, the electrical service and the controls, and usually has to happen on a scheduled day with the landlord’s approval.
The first question is whether replacement is needed. We check the age, condition and capacity of the existing units against the new layout. Sometimes a unit that looks old still has years left and enough capacity; sometimes a newer one is simply the wrong size for what the tenant is doing.
When replacement makes sense, a like-for-like swap is rarely exactly that. New units have different footprints, weights and electrical requirements, so curb adapters, structural checks and electrical changes are all part of the plan.
What a replacement involves
- Load calculation for the current or new use
- Curb adapter or new curb and roof work
- Structural review where weight changes
- Electrical feed and disconnect changes
- Crane lift and street or parking closures
- Controls, start-up and balancing
SCOPE OF WORK
What we deliver on a rooftop unit replacement
Assessment
Age, condition, refrigerant type and capacity of each existing unit, with a clear recommendation to keep or replace.
Sizing
A load calculation so new units are sized to the space as it will be used, not copied from the old nameplate.
Curbs and roof
Curb adapters or new curbs, flashing coordinated with the roofer so the roof warranty is protected.
Crane lift
Lift planning, permits for street or parking closures, and scheduling with the landlord and neighboring tenants.
Electrical and controls
Coordination with the electrician on feeds and disconnects, and new thermostats or building automation integration.
Start-up
Manufacturer start-up, economizer and controls checks, and a balance of the supply air after replacement.
HOW THE JOB RUNS
The replacement sequence
01
Assess and size
02
Release equipment and plan the lift
03
Prepare the roof
04
Lift, connect and start up
COMMON QUESTIONS
Rooftop unit questions
We look at age, condition, refrigerant type, repair history and whether its capacity fits the new layout. We give you a clear recommendation with the reasons.
Sometimes directly, more often with a curb adapter. New units rarely match old footprints exactly, and the adapter avoids cutting a new roof opening.
The area served by that unit will, usually for a day. We schedule replacements for mild weather and off-hours where possible.
Often. New equipment may have different electrical requirements, so we coordinate feeds, breakers and disconnects with the electrician.
We coordinate with the building’s roofing contractor so curbs and flashing are done in a way that protects the roof warranty.