A planned one-day rooftop replacement instead of an emergency
A machine-tool builder in Farmington Hills had a project office with no air conditioning and a rooftop unit locked out with a cracked heat exchanger. We restored cooling safely on the same visit, then replaced the unit on a day the customer chose, in one day on the roof.
- Same visitCooling restored safely in May
- 15 minutesFrom the customer's approval to the equipment order
- 1 dayOn site 8:15 AM, new unit running by 2:52 PM
The challenge
This customer engineers and assembles precision honing machines for automotive, aerospace and defense manufacturers in a 50,000 square foot plant. The project managers who run those builds sit in an office served by one rooftop unit, RTU 5.
That unit had been locked out at the disconnect for a long time. Its heat exchanger was cracked, which made the heating side unsafe to run, so the office had no air conditioning either. Summer was coming with a full schedule of customer builds. The office needed cooling now, and a safe, permanent answer before heating season.
The usual way this goes wrong is to treat it as two emergencies: a rushed repair in the summer, then a rushed replacement in the first cold week, with whatever unit the supply house has on the shelf.
What we did
1. Find the unit that actually serves the complaint
On April 30, 2026, Joe T traced the office complaint to RTU 5 instead of the nearest unit on the roof. On May 8, with the customer's agreement, he cut the lockout and brought the unit back as cooling only, with the unsafe heat section left off. The office set its thermostat to 69°F and the unit held it. That bought the office the summer, safely.
2. Make the replacement a planned job
Nick Greenstein had already recorded the nameplate data off units 5 and 7 during a no-heat call the previous November. Because that data was on file, Ed Keskeny could quote the replacement in early May without another trip to the roof: a Bryant 5-ton, 460-volt three-phase unit with an economizer, a curb adapter, a new disconnect, hoisting and the permit. In September Yosef Moflehi walked the roof again to check the unit and the thermostat map before the team went up.
3. Order the morning of approval
The customer approved the quote on September 3 at 10:00 AM. The order for the unit, the Siemens economizer, the curb adapter and the fused disconnect went to the supply house at 10:15 AM.
4. One day on the roof
On September 24 Steve Locher, Doug Hebert and Adam Route were on site by 8:15 AM. They removed the old unit, set the curb adapter and the new unit on R-454B refrigerant, reconnected gas, power and controls, and had it running by 2:52 PM. There are no callbacks on record.
Results
- Cooling all summer. The project office had air conditioning from May 8 on and never lost it.
- A planned day, not a breakdown. The replacement happened on a day the customer chose, with the parts on the truck, before heating season.
- One day, three installers, about 19 team hours. From removal to running in under seven hours on site.
- A current unit. R-454B refrigerant and an economizer, which uses outside air to cut cooling run time on mild days.
Worth knowing
Find the unit that actually serves the complaint, buy the customer time safely, then turn the replacement into a planned job with the data gathered before the quote. The U.S. Department of Energy's Better Buildings program found that emergency rooftop replacements usually cost much more than planned ones and leave no time to compare options, and recommends keeping a ranked list of replacement candidates priced in advance. That sequence is what separates a scheduled install from an emergency.
Sources: U.S. Department of Energy, Better Buildings: the business case for proactive rooftop unit replacement; U.S. Department of Energy: fix your rooftop unit before it breaks. From the AHS service records for this job.