Layer 4: three-fan circulation

The two-zone problem

Cold air stayed at the rear and hot air pooled in the cab. Air temperature at the A/C was not representative ofSarah's workstation or Chasey's possible locations.

Our airflow chain

Three marine fans push/mix air from the rear toward the front. Turning off even one creates a noticeablefront-temperature rise in our layout.

Aim for a loop

Supply cold air forward along one path and allow warmer return air to move back toward the A/C. Avoid aimingfans so they fight each other or short-circuit supply directly into return.

Product links

Quiet fan: our preferred option. Noisier fan: alternative. Compare airflow, noise, current, mount strength andfinger protection.

System rule

Do not judge a cooling upgrade at the vent. Judge it by the hottest occupied zone, humidity, energy usedand whether the system can recover that energy safely.

CHAPTER CHECK

• I can explain which heat path this step addresses.• I measured its effect at front, middle and rear - not only by touch.• I added its power, failure mode, maintenance and safety action to the system plan.