The rooftop unit over your Southside office turned fifteen. Now what?
Fifteen years on a flat roof off Butler Boulevard is a full career for a package unit. The question for the building is whether it gets one more repair or a planned replacement before the tenants notice.
The fork at fifteen
A rooftop package unit does its work in the worst place on the property: full sun, full rain, no shade, and nobody looks at it unless it fails. At ten years it is middle-aged. At fifteen, the compressor has run through roughly fifteen cooling seasons of seven or eight months each, the economizer has probably seized, the belt has been changed more times than anyone can count, and the control board has survived a decade of Northeast Florida lightning. The unit may still cool. The question is whether to keep paying for that or to plan its replacement on the building’s schedule rather than the unit’s.
What we check on an aging unit
A real inspection of a fifteen-year-old rooftop unit takes more than a glance at the filters.
- Compressor amperage and refrigerant pressures, read against the nameplate, to see how hard it’s working.
- Condenser and evaporator coil condition: fin loss, oil stains that mean a leak, years of pollen and roofing grit.
- Economizer dampers, actuator and sensors. On most Southside buildings these failed years ago and the unit has been running without free cooling.
- Blower motor, belt and pulleys, plus bearing noise.
- Heat section, gas or electric, and the safeties.
- Control board and wiring for surge damage and heat-brittled insulation.
- Cabinet, curb and roof penetration: rust-through, water intrusion, and the state of the roofing around the curb.
- Power draw over a run cycle, which is the number the owner feels on the JEA bill.
What usually fails, and what it means
| Failure | Typical age | Repair or fork? |
|---|---|---|
| Belt, contactor, capacitor | Any age | Repair, every time |
| Blower motor | 8-15 years | Repair, unless the compressor is also tired |
| Economizer actuator | 5-10 years | Repair; often ignored, shouldn’t be |
| Control board after lightning | Any age | Repair, with surge protection added |
| Condenser coil leak | 12-18 years | Fork: the coil is a large share of a new unit’s cost |
| Compressor | 12-20 years | Fork: at fifteen-plus, replacement usually wins |
| Heat exchanger crack (gas units) | 15-25 years | Replace; it’s a safety item |
What it costs, in words
Belts, contactors and capacitors are small enough to approve by phone. Motors and economizer parts are the middle. Coils and compressors on a unit past fifteen years run into the territory where a new unit, with a full warranty and lower power draw, costs only moderately more than the repair and comes with a crane day already in the budget. A replacement quote from Cook’s shows the unit, the curb adapter, the crane, any electrical work and the start-up as separate lines so an owner can see what the equipment costs versus what getting it onto the roof costs.
Crane day, from the manager’s side
- Inspection and measurement of the existing curb, electrical and gas or duct connections, weeks ahead.
- Curb adapter fabricated to the new unit’s footprint, so no roofing contractor is needed on the day.
- Crane permit and staging arranged, with the parking lot cleared where the crane sets up.
- Early morning lift. Old unit off, adapter on, new unit set, connections made.
- Start-up and commissioning with refrigerant charge, airflow and controls verified before the office opens.
- Documentation: nameplate data, start-up readings and warranty registration delivered to the manager.
Two mistakes we undo on Southside roofs
The first is replacing a failed unit with the same tonnage because that’s what was there. Office tenants change, a dental practice replaces an insurance office, a server room appears, and the load changes with them; the replacement should be sized to the space as it’s used now. The second is skipping the economizer on the new unit to save money. On a Jacksonville roof, free cooling on the many mild mornings from October through April is real savings, and an economizer that is commissioned and then checked at each maintenance visit pays for itself.
Planning instead of reacting
The buildings that handle this best keep a one-page sheet per unit: install year, service history, repairs and the last inspection’s readings. With that sheet, a manager can see a fifteen-year-old unit coming and budget its replacement for a shoulder season, when crane availability is good and the tenants won’t notice. Without it, the replacement happens in August with a tenant complaint attached. Cook’s maintains that sheet for buildings on a maintenance contract, with specifics [[CONFIRM WITH JERRY]], and runs commercial rooftop work across the Southside from its headquarters at 37 Fairmont Ln in Palm Coast, with 24/7 installation available when a building can’t wait for a weekend.
Rooftop unit questions from property managers
Can a new rooftop unit go on the old curb?
Usually, with a curb adapter engineered to bridge the old footprint to the new unit’s. That avoids roofing work and keeps crane time short. Occasionally a curb is too deteriorated and gets replaced, which we find on the inspection, not on crane day.
What does a replacement do to the building's electrical?
Modern units often draw less current than the ones they replace, but the disconnect, the wiring and the breaker are checked against the new nameplate before anything is ordered. If an electrician is needed, it’s scheduled before the crane.
How do I justify replacement to an owner who only sees repair bills?
With a per-unit history: what the unit has cost in the last three years, what it’s drawing in power, and what the next likely failure costs. Put against a new unit’s warranty and efficiency, the math usually argues itself at fifteen years.
Will tenants be without cooling during the swap?
For a few hours, scheduled before opening or on a weekend. On buildings with multiple units we sequence replacements so no floor loses all of its cooling at once.
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