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📘Split System Basics

📷 System Diagram

 

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Figure 1: A basic layout showing the indoor air handler, refrigerant lines, and outdoor condensing unit.

 

🧰 What is a Commercial Split System?

A commercial split system separates the HVAC components between:

  • An outdoor unit (compressor + condenser)

  • An indoor unit (evaporator coil + blower or air handler)

 

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Figure 2: Indoor evaporator unit paired with condensing unit.

 

🔧 Key Components

🔹 Outdoor Unit

  • Compressor

  • Condenser Coil

  • Outdoor Fan Motor

  • Weather-resistant housing

🔹 Indoor Unit

  • Evaporator Coil

  • Blower or Air Handler

  • May include electric heat or hydronic heating coil

 


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Figure 3: Diagram of an indoor evaporator coil and airflow.

 

📏 Typical Sizes and Capacity

  • Tonnage Range: 3 – 25 tons

  • Voltage: 208/230V or 460V (3-phase)

  • SEER Rating: Commercial SEERs usually range from 13 to 17

 

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Figure 4: General sizing chart by square footage and tonnage.

 

🧱 Installation Considerations

 

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Figure 5: Piping and line set routing for commercial split install.

 

  • Mounting slab or curb for the outdoor unit

  • Ensure line set length and elevation are within manufacturer limits

  • Proper drainage setup for indoor unit

  • Access space for filters, coil cleaning, and service

🧼 Maintenance Requirements

 

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Figure 6: Routine coil cleaning on a commercial split condenser.

 

✅ Advantages

  • Zoning flexibility

  • Quieter indoor operation

  • Easier indoor maintenance

  • More design flexibility for limited rooftop space

⚠️ Disadvantages

  • Not modular or scalable like VRF

  • More complex installation than packaged RTUs

  • Line set length limits may restrict placement

🛠️ Common Field Issues

  • Undetected refrigerant leaks from long line sets

  • Coil or filter fouling

  • Electrical faults on outdoor disconnects

  • Faulty thermostats or improper control wiring

📎 Training & Resources

🧠 Summary

Commercial split systems are a reliable HVAC option for small to mid-sized buildings where flexibility, performance, and localized control are priorities. Understanding proper design, maintenance, and installation principles ensures long-term efficiency and comfort.

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