First, let's calculate the approximate heat output of your equipment. A typical 1U server generates between 500-1000 BTU/hr (150-300W), while networking gear produces less. Your setup likely generates:

// Sample heat calculation in Python
servers = 10 * 750  # BTU/hr (mid-range estimate)
network_gear = 12 * 250
total_btu = servers + network_gear
print(f"Total heat output: {total_btu} BTU/hr (~{total_btu/3.41:.0f} watts)")

The single supply duct with powered fan suggests a makeshift approach. Key issues:

• No dedicated return path (ceiling cavity isn't proper ducting)
• Airflow direction conflicts with hot air's natural rise
• No temperature-controlled operation

Option 1: Ductless Mini-Split System

I recommend a 12,000 BTU (1-ton) mini-split for your 144 sq ft room:

# Pseudocode for temperature control logic
def cool_room():
    current_temp = read_sensor()
    if current_temp > 75:  # target temp
        activate_compressor()
    elif current_temp < 70:
        standby_mode()

Pros:
- No ductwork modifications needed
- 208V models available for better efficiency
- Quiet operation (important for adjacent offices)

Option 2: Smart Exhaust System

For a lower-cost solution, implement an automated exhaust fan:

// Arduino snippet for thermostat-controlled exhaust
#include 
#define DHTPIN 2  
#define FAN_PIN 3

DHT dht(DHTPIN, DHT22);

void setup() {
  pinMode(FAN_PIN, OUTPUT);
  dht.begin();
}

void loop() {
  float temp = dht.readTemperature();
  if (temp > 75.0) {
    digitalWrite(FAN_PIN, HIGH);
  } else {
    digitalWrite(FAN_PIN, LOW);
  }
  delay(10000);
}

Even with cooling, proper airflow matters:

1. Implement hot aisle/cold aisle configuration
2. Use blanking panels in empty rack spaces
3. Seal cable penetrations in the floor/ceiling

Set up temperature logging with a Raspberry Pi:

# Python script for temp logging
import Adafruit_DHT, time

sensor = Adafruit_DHT.DHT22
pin = 4

while True:
    humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
    if temperature is not None:
        with open("temp_log.csv", "a") as f:
            f.write(f"{time.time()},{temperature}\n")
    time.sleep(300)

For enterprise-grade monitoring, consider SNMP integration with your existing network gear.

In server room configurations like yours (12'×12' with 10-15U of equipment), heat generation typically ranges between 3,000-5,000 BTU/hour. Your observed temperature delta (80°F to 86°F) suggests inadequate heat dissipation. Let's analyze the components:

# Sample heat calculation (Python)
btu_per_server = 400  # Typical 1U server
total_btu = 10 * btu_per_server + 4*150 + 3*100  # Switches + routers
print(f"Total heat load: {total_btu} BTU/hr ≈ {total_btu/12000:.1f} tons cooling")

The single inlet/outlet duct system creates a negative pressure environment. This explains why opening the door helps, but it's not sustainable. The existing airflow might be as low as 100-150 CFM, while you need at least 300-400 CFM for proper heat exchange.

Here are three viable approaches I've implemented in similar scenarios:

// HVAC sizing formula (JavaScript)
function calculateCoolingCapacity(roomSize, equipmentWattage) {
  const btuPerWatt = 3.412;
  const roomFactor = roomSize * 25; // 25 BTU/sq.ft baseline
  return Math.ceil((equipmentWattage * btuPerWatt + roomFactor) / 12000);
}
// Example for 5000W load:
console.log(calculateCoolingCapacity(144, 5000)); // Outputs required tonnage

For your 12×12 room, a 1-ton (12,000 BTU) mini-split would be ideal. Installation requires:

• 2" hole through wall for refrigerant lines
• 208V electrical connection
• Condensate pump ($50-100) to handle drainage

If structural modifications are restricted, consider a dual-hose portable unit (14,000 BTU model) with these modifications:

# Bash script to monitor temperature thresholds
#!/bin/bash
THRESHOLD=75
CURRENT_TEMP=$(get_temp_sensor_reading)
if [ $CURRENT_TEMP -gt $THRESHOLD ]; then
  /usr/bin/irsend SEND_ONCE ac_power ON
fi

For a lower-cost approach, install two 300 CFM inline fans:

• Intake fan with MERV 8 filter
• Exhaust fan ducted to building return
• Thermostat-controlled variable speed

When installing any solution:

// Sample Nagios config for temperature monitoring
define service {
  service_description Server Room Temp
  check_command       check_nrpe!check_temp
  normal_check_interval 5
  max_check_attempts 3
}

Remember to implement temperature monitoring regardless of which solution you choose. I recommend using simple Raspberry Pi-based sensors with Grafana visualization.