RTU High Static — Low Airflow and Poor Cooling
- Interactive decision labs
- Built by working technicians
- Path-based verifiable certificate
- Exam preparation only
- Worldwide online
Commercial HVAC / RTU
~15 min
advanced
The call
Retail space is warm at the back of the building. The RTU runs constantly and the store manager says the vents 'barely blow'.
- Equipment
- 10-ton packaged RTU, belt-drive supply fan, R-410A, design external static 0.8" W.C.
- Ambient
- 91°F
- Site notes
- Filters were changed two weeks ago by the customer. Unit cycles on and off intermittently on a safety during the hottest part of the afternoon.
Decision 1 of 4
Supply air is 51°F and return is 79°F — a 28°F split, far wider than the 18–20°F you would expect.
A 28°F split with weak airflow at the diffusers tells you what?
Where this lab sits
This is one module lab from Commercial HVAC / RTU. The full path adds sealed systems, defrost, rack-system orientation and natural-refrigerant safety, each ending in a lab like this one.
Open the full pathNext lab: Residential No-Cool — Split System Not CoolingNext lab: Residential No-Heat — Gas Furnace Short Cycling on IgnitionNext lab: Frozen Coil / Airflow RestrictionNext lab: Superheat / Subcooling DecisionNext lab: Walk-in Cooler Not Holding TemperatureNext lab: Ice Machine Not Making IceNext lab: Reach-in / Prep Table Not Holding TemperatureNext lab: Walk-in Freezer Defrost FaultNext lab: Natural Refrigerant Safe-Handling DecisionNext lab: Rooftop Unit Not CoolingNext lab: RTU Economizer Stuck — No Free CoolingNext lab: RTU Gas Heat — No Heat / Ignition Fault