Trane Premieres Ascend Model ACX, Air-to-Water Heat Pump and Redesigns Precedent Rooftop Units


Trane – by Trane Technologies, a global climate innovator – has released the Ascend Air-to-Water Heat Pump Model ACX, the first air-to-water pump solution in its portfolio that provides both electric heating and cooling, giving building owners an avenue to pursue decarbonization via electrification. Trane also announced it is bringing a new generation of Precedent rooftop units to market, consolidating the legacy Precedent and Voyager 2 offerings. The first models in the redesigned series, the Precedent standard efficiency 6- to 25-ton units, are available now.

Ascend Air-to-Water Heat Pump Model ACX, and Precedent Enabled by Symbio 700 units from Trane (left to right).

Trane’s Ascend air-to-water heat pump model ACX combines chiller and heat pump technology to both heat and cool a building using electricity. In cooling mode, the model ACX moves heat from inside the building to the outside. In heating mode, a reversing valve changes the flow of energy to bring heat from outside of the building to the inside. The heat pump moves heat using a compressor, rather than simply generating heat. This technique can make heat pumps up to three times more energy-efficient than other forms of electric heating.

“Over 180 cities, more than ten counties, and eight states across the U.S. have goals to power their communities with 100% clean, renewable energy. As the grid gets greener, the need for full electric heating and cooling is growing,” said Dave Molin, Vice President of Trane Product Management, Equipment, Controls and Digital.

“Engineers, contractors, and building owners want to lower fossil fuel consumption and reap the efficiency and sustainability benefits of electrified heating and cooling,” Molin adds. “By joining Trane’s best-in-class chiller expertise with the Ascend air-to-water heat pump, Trane is making electrified heating and cooling a realistic option for customers.”

As a result of its boiler-free heating, the model ACX achieves high energy efficiency for cooling and heating. The unit’s heating efficiency exceeds ASHRAE® standard 90.1-2019: 2.77 COP for heating and a cooling requirement of 9.215 EER.

The Ascend model ACX can help builders and operators meet current HVAC regulations, attain certifications or achieve a net-zero energy building with its all-electric functionality and other energy-efficient features.

  • Air Conditioning, Heating, and Refrigeration Institute (AHRI) compliant.
  • Variable-speed fans, variable speed permanent magnet motors, intermediate discharge valves on the compressor, and braze plate evaporators enhance efficiency.
  • Dual expansion refrigerant flow valves optimized for heating and cooling modes enable system reliability.
  • The heat pump generates hot water temperatures up to 140°F and operation down to 0° ambient.
  • The Symbio 800 unit controller comes factory-mounted and pre-programmed with algorithms that respond to building conditions and maintain efficient chiller plant operations. It also enables secure remote connectivity and open standard protocols for seamless integration with a Building Automation System (BAS) such as Tracer SC+.
  • A scroll compressor makes electrification more affordable and practical without compromising efficiency or sound.
  • The fin and tube coil support a smaller footprint, and the transverse “V” condenser coils are easy to access for cleaning and service.

The new Precedent portfolio will include capacities from 3-25 tons, a full range of tonnages and heating types, and improved efficiency levels. The new single-product family of light commercial unitary rooftops will be released in phases now through 2024.

Available immediately, the Precedent standard efficiency 6- to 25-ton cooling and gas units feature various upgrades, including part-load efficiency ratings that comply with new industry requirements. New units are enabled by the Symbio 700 controller to easily monitor and control HVAC systems and harness building connectivity for advanced troubleshooting and energy management. Additional benefits include:

  • Compliant with U.S. Department of Energy (DOE) 2023 minimum efficiency regulations 
  • New serviceability enhancements include hinged access to the control panel, color-coded wiring with keyed connectors, and a direct drive plenum fan and motor.
  • Connection with the Symbio Service and Installation App for easy commissioning, monitoring, and troubleshooting.
  • A new three-year parts warranty provides extra peace of mind.

Four product options in the Precedent line are available and suit a range of applications:

  • Cooling – optional electric heat, is an all-electric option.
  • Gas Pack – pairs electric cooling with gas heating.
  • Heat Pump – couples refrigerant-system cooling and heating, all-electric.
  • Hybrid/Dual Fuel – combines heat pump cooling and heating with gas auxiliary heating.


About Trane

Trane – by Trane Technologies, a global climate innovator – creates comfortable, energy-efficient indoor environments for commercial and residential applications. For more information, visit