Direct Expansion Evaporator & Condenser Coils for Rooftop Heat Pump Units

Rooftop package units are widely used in commercial and industrial facilities due to their compact design, ease of installation, and ability to provide both cooling and heating through a single packaged system. At the heart of these rooftop heat pump units are the direct expansion (DX) evaporator and condenser coils, which handle the critical heat exchange process. Their engineering, material selection, and performance directly affect the system’s overall energy efficiency, reliability, and service life.

How DX Coils Work in a Heat Pump Rooftop Package Unit

In a heat pump rooftop unit, the flow of refrigerant reverses depending on the operating mode:

Cooling Mode

• Evaporator coil (indoor air path): absorbs heat from the supply air; refrigerant evaporates inside the tubes.

• Condenser coil (outdoor section): rejects heat to ambient air; refrigerant condenses into liquid.

Heating Mode

When the reversing valve switches:

• The outdoor coil becomes the evaporator, absorbing heat from cold outdoor air.

• The indoor coil becomes the condenser, releasing heat to the supply air stream.

This dual-function operation requires coils engineered to handle bidirectional refrigerant flow, defrost conditions, and seasonal mechanical stresses.

Key Benefits of DX Evaporator & Condenser Coils in Rooftop Heat Pumps

1. High Energy Efficiency

Optimized tube expansion, fin density, and refrigerant distribution ensure maximum heat transfer, reducing compressor power consumption.

2. Compact and Lightweight

Especially with microchannel technology, coils provide more capacity in smaller footprints—ideal for rooftop packaged equipment with strict weight limits.

3. Durable for Outdoor Conditions

Condenser coils are exposed to harsh weather; coatings such as:

• Epoxy coating

• Gold fin coating

• Blue hydrophilic coating
  Enhance corrosion protection.

4. Compatible with Modern Refrigerants

Coils are engineered for higher operating pressures demanded by R410A and new low-GWP refrigerants.

5. Reliable Reversing Operation

Coils must withstand:

• Freeze–thaw cycles in winter

• High refrigerant velocities

• Defrost heating cycles

Proper material thickness and structural reinforcement ensure long service life.

Custom Coil Manufacturing & Replacement Services

If your rooftop package heat pump requires a new coil or an OEM-equivalent replacement, custom coils can be manufactured according to:

• Drawings

• Coil samples

• Dimensional measurements

• Refrigerant type and capacity

Options include copper/aluminum DX coils, microchannel condenser coils, epoxy-coated coils, and stainless-steel headers for corrosive environments.