What Is Ambient Temperature and Why It Matters

Ambient temperature is the room air temperature surrounding your mortuary cooler. When ambient rises, the refrigeration system must work harder to reject heat, which increases compressor runtime, electrical cost, component wear, and the risk of temperature drift.

• Target room range: 65°F–75°F (18°C–24°C) in most facilities.
• Above 80°F: Expect longer cycles, higher head pressures, and reduced lifespan.
• Below 60°F: Some systems may short-cycle or require low-ambient controls—consult your spec.

What Is THI (Temperature-Humidity Index)?

THI combines air temperature and relative humidity to describe how “heavy” the air feels and how difficult it is for a system to remove heat and moisture. High humidity increases latent load on the evaporator and overall condenser work, especially during warm seasons.

• Higher THI = higher heat load: The system works harder to remove both sensible heat (temperature) and latent heat (moisture).
• Humidity drives condensation and icing risk: More defrost cycles, more frequent coil cleaning, and stricter door-open discipline are needed.
• Design implication: Facilities in humid climates often require larger capacity, remote-condensing, or enhanced airflow solutions.

How Ambient Temperature and THI Impact Sizing

Proper sizing isn’t just about interior setpoint (e.g., 36–39°F). It must account for external conditions and usage patterns that add heat to the box.

1. Room Conditions: Typical ambient and humidity, worst-case summer/winter peaks, and ventilation quality.
2. Door Openings: Frequency/duration (high-volume facilities may need additional capacity and better gaskets/air curtains).
3. Load Profile: Average daily cases, peak surges, rack/roll-in configuration, and product “pull-down” expectations.
4. Construction: Panel insulation (thickness, foam type), floor details, and thermal breaks.
5. Controls: Defrost strategy, low-ambient kits, pressure controls, and fan management.

Rule of thumb: Hotter, more humid rooms (high THI) → plan for higher capacity, consider remote condensing, and ensure stronger condenser airflow and coil surface area.

Choosing the Right System Type for Your Climate

Self-Contained (Integrated) Systems

• Best for: Smaller rooms, conditioned spaces, moderate climates, simpler installs.
• Considerations: Rejects heat into the room; watch ambient rise and ensure adequate ventilation.

Remote Condensing Systems

• Best for: Walk-ins, high-volume, warm or humid regions, noise/heat sensitive spaces.
• Advantages: Moves heat and noise out of the room, stabilizes ambient, improves service access and longevity.

Roll-In vs. Upright Configurations

• Roll-In: Faster loading, fewer door-open minutes, helpful in high traffic—reduces warm/moist air infiltration.
• Upright: Space-efficient, individual doors can localize infiltration but require disciplined door management.

Seasonal and Regional Planning

• Warm/Humid Regions: Aim for remote condensers, larger condenser coils, adequate makeup air, and dehumidification where possible.
• Cold Regions: Low-ambient controls for winter; protect against short-cycling and oil return issues.
• Shoulder Seasons: Rapid THI swings—schedule pre-summer and pre-winter maintenance.

Room Design Tips That Lower THI Load

• Keep the equipment room conditioned and ventilated; avoid boiler rooms or sun-exposed spaces.
• Seal penetrations, maintain gaskets, and use door closers/air curtains in high-traffic setups.
• Provide condenser clearance for airflow; clean coils quarterly (or more in dusty environments).
• Add hygrometer/thermometer logging to track THI trends and intervene early.

Maintenance That Protects Capacity

• Annual Service: Refrigerant checks, electrical inspection, defrost verification, thermostat calibration.
• Quarterly Tasks: Clean condenser/evaporator coils, inspect drains, sanitize door gaskets and thresholds.
• Operational Discipline: Limit door-open time, organize racking for faster access, and document temperature/THI logs.