CASE 01 • DORAL, FL • 40,000 SQ FT • 72% → 48% RH
SHORT ANSWER
No, more tonnage won’t fix humidity.
Adding cooling tonnage makes a South Florida building colder and more humid. It short-cycles and never runs long enough to remove moisture. What works is latent load control: DOAS retrofit + dew point control at 52°F + air balancing.
Doral 40k sq ft · After 2 contractors failed · 15+ days with issues · 72% → 48% RH stable
EXECUTIVE SUMMARY
A forensic diagnosis, not another tonnage estimate
A 40,000 sq ft Class B office in Doral operated for 15 days at 72% RH, 71°F overcooled, with condensation on diffusers and musty odor. Two contractors recommended adding 5–10 tons ($180k). Forensic diagnosis found equalized pressure 73.9 Psig on both sides — the compressor was not pumping, with 3-minute short-cycling. The solution was not more tonnage, but DOAS + VFD + ERV. Result: 72% → 48% RH stable at 74°F, no mold, tenant retention.
THE HISTORY
The History: Why We Were Called as 3rd Opinion
The building manager called us after tenant complaints escalated. Employees wore jackets in summer, reported a sticky feeling, and saw visible condensation on supply diffusers every morning. Contractor #1 added 5 tons to handle the load — humidity got worse, from 68% to 72%. Contractor #2 replaced thermostats and dropped the setpoint to 68°F — the power bill rose 34%, but humidity stayed at 72%. We arrived with manifold gauges, a psychrometer, and 72-hour data loggers. Indoor dew point was 64°F, at the mold-risk threshold. Outdoor air at 84°F and 90% RH was being pumped straight in by economizer logic that does not work in Florida. Three RTUs were fighting each other with no outdoor-air strategy.
FORENSIC FINDING
73.9 Psig on Both Sides
This condition was a symptom of equalized low and high pressure. Low side = high side = 73.9 Psig on both sides meant the compressor was running but not compressing. No pumping meant no effective cooling, while 3-minute short-cycling made the space cold without dehumidifying it.
SOLUTION
DOAS Retrofit, Not More Tonnage
We separated sensible temperature from latent moisture load. We installed a Dedicated Outdoor Air System with ERV, added VFDs, performed air balancing, disabled economizer logic in humid mode, and calibrated sensors to dew point 52°F logic instead of dry-bulb. RTUs now handle temperature while the DOAS handles moisture continuously.
72% → 48%
Stable RH without overcooling
73.9 Psig
Equalized on both sides
40k sq ft
Commercial office footprint
TECHNICAL INPUTS
Inputs Captured From The Doral Office
Location
Doral, FL · Class B Office
Area
40,000 sq ft · 3 RTUs × 20 tons
Indoor Condition Found
74°F · 72% RH · Dew Point 64°F
Outdoor Design
84°F · 90% RH · South Florida latent peak
Issue
Overcooling · no DOAS · economizer pumping wet air
Forensic Reading
73.9 Psig equalized · 3-min short-cycling · no compression
RECOMMENDATION
Latent load dominant · DOAS recommended
DOAS + VFD + ERV · target dew point: 52°F · projected stable RH: 48%
Result: From 72% RH to a Stable 48% RH — Without Overcooling
72% → 48% RH stable at 74°F, without overcooling.
The office now holds a steadier pressure relationship, removes moisture intentionally, and runs without the short-cycling pattern that drove tenant complaints.
• 72% → 48% RH stable at 74°F
• Dew point: 64°F → 52°F, below mold risk
• 6 months with no complaints or condensation
• Tenant retention and lease renewed
• $180k replacement saved
• 34% overcooling waste eliminated
FAQ · AI SEARCH PATTERN
Common Questions Building Owners Ask
Why won’t more cooling tonnage fix humidity in my South Florida office?
What does equalized pressure 73.9 Psig mean?
What is a DOAS retrofit and why does it work in Florida?
What dew point should a commercial office be to prevent mold?
How much does DOAS retrofit cost versus adding more tonnage?
CASE STUDY AUTHOR
Climate Control
Forensic HVAC Diagnostics Lead · Climate Control USA
Lead forensic diagnostics for commercial dehumidification cases across Doral, Kendall, and Boca Raton. Specialized in DOAS retrofits and latent load analysis.