Key features of the Azanefreezer include:

  • Twin screw compressors
  • Low charge, low pressure receiver
  • Reverse cycle defrost
  • High efficiency, low charge aluminium evaporators
  • Integrated ammonia gas detection system
  • Fully automatic oil recovery
  • Welded steel pipework construction
  • Dual relief and standard three way changeover valve for ease of maintenance
  • Powder coated mild steel electrical panel (option for stainless steel) complete with anti-condensation heaters and light
  • PLC control
  • HMI user interface
  • Epoxy paint finish

Refrigerant type

Ammonia is produced by biological processes, is naturally decomposed, and does not add to the global greenhouse effect.

The Azanefreezer offers:

  • Quick installation
  • No plantroom required
  • Low installation costs
  • Low maintenance costs
  • No ongoing water, effluent and water treatment costs
  • High efficiency control including floating head pressure control and EC condenser fans
  • Low total cost of ownership (TCO)
  • Very low charge of ammonia - as low as 0.9kg/kW (5lb/TR)
  • Easy relocation should the need arise

Azanefreezer Case Studies

  • Pinneys Annan


    Pinneys of Scotland, part of the Youngs Seafood Group, is a leading processor of Scottish smoked salmon and are based at Annan, Dumfriesshire. Cooling is a key requirement for their production processes and the majority of the factory was installed using systems operating with R22 refrigerant. Under the Montreal Protocol and subsequent European and UK legislation, the phasing out of R22 comes to a conclusion at the end of 2014 and so Pinneys needed to develop a strategy to meet this deadline.

    Pinneys asked their existing maintenance provider, Star Refrigeration for support with their phase out strategy. This involved looking at a variety of high, medium and low temperature cooling requirements on site currently running on R22 and assessing an appropriate alternative solution. Key requirements were to keep the facility operational during the changeover from R22, provide  a solution that offered long term cooling security for the site and to deliver a solution that balanced efficiency and capital cost.

    A number of options were considered including retrofitting systems with alterative gases, installing new HFC refrigeration systems and switching to natural refrigerants. 

    A critical part of the R22 strategy was conversion of the factory’s cold store where frozen product is stored at -25°C before further processing.  This chamber was cooled by two existing R22 refrigeration plants housed in different plant rooms. Both plants were assessed for possible gas conversion but due to their age, condition and the need to retain the cold store operation during any conversion works, this was ruled out. A decision was therefore made to look at new equipment.  

    One of the R22 plant rooms had been earmarked as the location for a new ammonia/glycol refrigeration plant which would serve other areas of the factory and the other was ruled out due to access issues. This meant that any new equipment would need to be located elsewhere. Pinneys were keen to avoid the added cost of building a new plant room and so packaged equipment with its own enclosure was preferred.

    Options for refrigeration plant using synthetic refrigerants such as R404A and R407F were considered but Pinneys were concerned about the long term availability of these refrigerants following news of the phase down programme detailed in the European f-gas regulation earlier in 2014. A decision was made to look at natural refrigerant alternatives.

    Star proposed their Azanefreezer system, an air-cooled, ammonia refrigeration system for cold storage applications.  Its packaged design avoids the need for a plant room and it can be located at ground or roof level on either a concrete plinth or steel frame. Azanefreezer’s combination of ammonia refrigerant, Star low pressure receive technology, EC fan and PLC control technology delivers efficiencies 15% to 20% higher than traditional HFC technology and with a refrigerant charge that is 80% less than pumped circulation ammonia.

    Two pipes between the Azanefreezer package and cold store evaporators keeps site installation time to a minimum. All equipment requiring regular inspection is located within the package, simplifying maintenance and eliminates the need for roof void valve stations.

    Alex Henderson, Key Account Manager at Star Refrigeration said, “As a long standing maintenance customer, we have been working with Pinneys for a number of years. The latest project involved the development of a long term refrigeration solution for the Coldstore plant as well as the rest of the site. It has reduced the amount of refrigeration equipment and helped improve both operating temperatures and efficiency.

    Using our packaged Azanefreezer concept avoided the need for a new plant room and we were able to position and commission the new coldstore plant before decommissioning the existing equipment.”

    Gary Parker, Pinneys Engineering Manager, said “Star Refrigeration have a long history of installing and maintaining plants both at Pinneys and also across the wider Young's Seafood group. 

    This is our first ammonia system at Annan and Azanefreezer’s low ammonia charge was a big reason for selecting it over more conventional ammonia solutions. Since its installation, our cold store temperatures have noticeably improved.”

    Star Refrigeration is the UK’s leading independent industrial refrigeration engineering company. Star focuses on the design, manufacture, installation, commissioning and maintenance of industrial refrigeration systems. The company offers a turnkey package to all users of refrigeration plant.

    Established in Glasgow in 1970, Star has over 300 employees nationwide and provides fast response 24-hour technical support from a network of nine branches to customers throughout the UK. Star’s technical advisory arm, Star Technical Solutions (STS), operates as an independent consultancy providing advice on engineering issues. Star also owns food freezing and chilling equipment specialist Starfrost; mechanical and electrical contractor Star Mechanical and Electrical Solutions; internet-based learning solutions i-know.com; and Star Renewable Energy providing natural fluid district heat pump technology.


  • Brakes, Bishops Stortford


    A leading distribution company has recently upgraded its existing freezer plant system to the modular air-cooled, low charge ammonia Azanefreezer. Located in Bishop's Stortford, Brakes supplies the UK food service industry with a comprehensive range of fresh, grocery, frozen and non-food products.

    The existing 40 year old ammonia refrigeration system had come to the end of its operational life and replacement equipment was required. The traditional approach would have been to replace with a pumped circulation ammonia system but the customer wanted to improve operating efficiency and reduce refrigerant charge. Star was invited to propose an upgrade solution focusing on these two key criteria.

    The solution was to install Star’s AF250 Azanefreezer. This air cooled, packaged unit incorporates twin screw compressors, air cooled condenser, electrical panel and reverse cycle defrost system inside a compact housing. This avoids the need for a new plant room and minimises installation time, with the package being installed on the roof of the existing refrigeration plant room.

    The high performance industrial freezer boasts a range of eco-friendly benefits, including the low ammonia charge requested by Brakes. Azanefreezer reduces Brakes existing ammonia system refrigerant charge from an estimated 5,000kg to just 188kg. 

    Alex Henderson, Key Account Manager - Food Market, says: “This reduction in charge, coupled with zero global warming potential, provided Brakes with the environmentally responsible solution they were looking for.”

    He adds: “As a natural refrigerant system, Brakes have invested in a long term solution that will be exempt from any future environmental legislation laws. With a 25 year life cycle when run at maximum operational performance, the system is a cost effective choice that will ensure Brakes produce stays fresh.”

    Modular, air cooled and incorporating a range of energy efficient features, the new system will help to reduce running costs as well as combat greenhouse gas emissions.

    Azanefreezer combines efficiency, reliability and unrivalled build quality, which will ensure Brakes continues to deliver its clients an unmatched level of service. The innovative modular design makes it efficient to relocate if necessary, thereby making it a cost effective option in a dynamic business. Also integrated into the system is an exclusive reverse cycle defrost function - currently the only system to offer this – which defrosts more efficiently as opposed to the alternative of installing electric heaters in the cooler.

    The upgraded system complies with European health and safety regulations and offers Brakes operators and management the peace of mind that they are working with premium quality equipment.

    Over the years, Star has built a strong working relationship with Brakes and is the food service supplier’s go-to solution for refrigeration upgrades, new built facilities and maintenance contracts across its UK plants.

    Ian Hunt, Brakes' Group Engineering Manager, said, “Star has a long history of installing and maintaining plants for Brakes. The Bishop’s Stortford Azanefreezer represents another successful collaboration and follows on from the recently completed distribution centre at Newhouse, Glasgow, which in turn followed on from Warrington last year and Reading before that.”