VZH 4-11TR

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More about the features of a VZH 4-11TR

Several specific aspects of the compressor design render advanced performance, such as:

Optimization for varying pressure ratios and modes
Small scrolls VZH feature Intermediate Discharge Valves (IDVs). The IDVs inside the small platform are decisive to the system efficiency.
The isentropic efficiency of a scroll compressor reaches a maximum at the built-in pressure ratio. When a compressor is operating below this built-in pressure ratio the efficiency drops due to overshoot: the discharge gas is at a pressure above the condensing pressure, the compressor over compresses the refrigerant.

The IDVs in the 4-11TR models partially avoid over-compression as they release the refrigerant before the built-in pressure ratio. This early release avoids efficiency losses due to overshoot and thus significantly enhance the energy efficiency for A/C systems at part-load conditions. The wide operating map makes the compressor suitable for very varied cooling and for heating applications, from 3 to 33kW of heating capacity.


Evaporating temperature -7°C; Condensing temperature 50°C; Superheat 5K; Subcooling 5K

Permanent magnet motor
The efficiency comparison between asynchronous and synchronous motors shows instantaneously the great advantages obtained when using a permanent magnet motor technology with:

  • Uniform motor efficiency in operation always above 92%. This leads to a lower power consumption,
  • Coolant stays cooler: the motor being more efficient, it will transfer less heat to the refrigerant and thus enhanced the compression efficiency.

Wide capacity modulation
The inverter drive modulates the cooling capacity from 15% to 100% for VZH 4.7 TR and from 17% to 110% for VZH 8-11 TR with a single compressor, which is very relevant for a variety of demanding applications where low part loads are needed.

Compact and reliable design
The 5 compressor displacements have the same dimensions and a compact footprint. This allows a cost-effective and flexible design over a wide range of cooling capacities.

Furthermore, the IDVs significantly reduce the stress level on mechanical components at start-ups.

Brochure - Danfoss VZH inverter scroll compressor

Advanced efficiency, precision cooling: Design an HVAC system like no other

Stand out in the commercial HVAC and process cooling marketplace by boosting your unit performance and shortening development time with the Danfoss pre-qualified and manifoldable 4-26TR inverter packages.

Features and benefits

Optimization for varying pressure ratios and modes with Intermediate Discharge Valves (IDVs) and modes

Permanent magnet motor technology

Wide capacity modulation

Compact and reliable design

Danfoss Learning courses on VZH inverter scrolls

Learn more with Danfoss Learning

Danfoss Learning offers two courses on VZH inverter scrolls, giving you information about benefits and characteristics, and guidelines for installation and troubleshooting.



Coolselector®2: We did complex — you do awesome

Coolselector®2 features unbiased calculations for the selection of refrigeration and air conditioning components based on the user’s requirements or based on standard operating conditions.



COMPASS is a software program that helps you to find the best Danfoss alternative for compressors for replacement. The purpose of COMPASS is to provide a direct comparison between Danfoss and competitor products.

Case stories