Rooftop Packaged Unit (RTU) for Commercial Office

All-in-one rooftop packaged AC, integrated cooling, fan, filter, controls; widely used for office buildings, large open areas.

1. Core Design Parameters & Sizing

Standard Operating Conditions

Indoor: 24–26°C, 45–60% RH

Outdoor design temp: 35–43°C DB (general regions)

Air change rate: 6–10 ACH for open offices; 8–12 ACH for meeting rooms

Load Sizing Rule

General office: 180–220 W/㎡ (normal insulation, standard lighting/occupancy)

Dense office/glass facade: 220–280 W/㎡

Unit tonnage reference:

1 RT ≈ 3.516 kW cooling capacity

2. Key Functional Configurations (Office Priority)

2.1 Basic Sections

Air intake & Filtration

Standard: G4 pre-filter + F7 medium filter

Optional: PM2.5 filter for better indoor air quality

Galvanized/stainless steel air louver, rain & wind proof

Cooling & Heating

Standard: Air-cooled direct expansion (DX) system

Heating options:

Electric heater (simple, easy installation)

Gas-fired heat exchanger (low running cost for large areas)

Hot water coil (connect building central heating)

Optimized fin/tube coil, hydrophilic coating, anti-fouling

Supply/Return Fan

Belt-driven or direct-drive centrifugal fan

Medium static pressure: 180–300 Pa (for long duct runs)

Low noise & vibration, rubber/spring isolators

VFD fan (energy saving, adjustable airflow)

Compressor & Refrigerant

Scroll compressor (stable, low noise, high efficiency)

Refrigerant: R410A / R32 (environment-friendly)

Multi-compressor design for large RTU: staged loading, part-load energy saving

2.2 Fresh Air & Ventilation (Office Mandatory)

Built-in motorized fresh air damper, adjustable fresh air volume

Comply with ventilation standard: ≥30 m³/h per person

Optional energy recovery wheel (ERV) to cut cooling/heating load

2.3 Humidity & Comfort

Basic dehumidification function for summer

Avoid over-cooling; maintain RH 45–60% for staff comfort

3. Construction & Material (Outdoor Rooftop Use)

Casing: Heavy gauge galvanized steel + polyester powder coating, anti-rust, anti-UV, rainproof

Base frame: Reinforced steel channel, anti-corrosion treatment

Drain pan: Stainless steel, sloped design + P-trap, prevent condensate leakage

Fully enclosed cabinet, good air tightness, reduce air loss

4. Control System

Microprocessor DDC controller, precise temp control (±0.5°C)

Functions: Timing on/off, fan delay, defrost protection, fault alarm

BMS communication interface (Modbus/BACnet) for central building management

Group control for multiple units

5. Special Options for Different Scenarios

Low noise version: Extra acoustic insulation, silencer section (for office near rooftop)

Economizer mode: Free cooling with outdoor cool air (save energy in spring/autumn)

Explosion-proof / corrosion-resistant: For special surrounding environment

Hot climate upgrade: Larger condenser area, high ambient motor (up to 50°C)

6. Installation & Maintenance Notes

Install on reinforced rooftop concrete base or steel support, keep level

Reserve maintenance space around unit (≥800mm)

Duct flexible connector to isolate vibration to indoor ceiling

Regular filter cleaning, coil washing, condensate drain inspection