Comprehensive marine air conditioning system rebuild on m/v Sunnavik

In January 2024, our engineering team executed an advanced project in the port of Terneuzen. The primary objective of this service intervention was a complete marine air conditioning system rebuild on the m/v Sunnavik, covering the main Air Handling Units (AHU) for both the port and starboard sides.

Detailed scope of installation and assembly works

We initiated the project by constructing new foundations beneath the central unit to support the upgraded refrigeration system. At the core of the new setup on each side, we installed a heavy-duty Frascold Z50-168Y compressor. As part of the modernization, new critical refrigeration components were fitted, including an RDYG 40 refrigerant receiver, an oil separator, and a suction accumulator. Additionally, two CJR-612424 air-cooled condensers were mounted on the open deck.

Such an extensive marine air conditioning system rebuild required highly precise pipe prefabrication. During the structural work, hull penetrations were made for the piping, securely sealed using certified Roxtec transit frames. The system was equipped with a brand-new electrical cabinet and control panel: we installed Danfoss KP 15 pressure switches for reliable high-pressure protection and KP 5 units to regulate compressor capacity and fan operation. The liquid and return lines were fitted with high-quality Danfoss armature, featuring GBC shut-off valves, NRV 35 check valves, 48 DM filter driers, EVR 35 solenoid valves, and new TE 55 thermostatic expansion valves with orifice no. 10.

Pressure testing and post-commissioning parameters

The completed freon installation underwent a rigorous 24-hour leak test using dry nitrogen at a pressure of 20 bar. Following positive verification, the system was evacuated to -1 bar and charged with 50 kg of R407C refrigerant.

Operational measurements taken post-commissioning confirmed flawless system performance. The recorded compressor working pressures were: 4.5 bar on suction, 14 bar on discharge, and an oil pressure of 8.5 bar, with the evaporation temperature reaching a stable 5 degrees Celsius. The high-pressure (HP) safety switch engaged correctly, shutting down the compressor at 22 bar, ensuring a safe margin relative to the receiver’s safety valves. In accordance with standard engineering practices, we recommended an oil change for the compressors after approximately 24 hours of continuous running.

Are you looking for a trusted partner to modernize your fleet’s climate control? Discover our full capabilities in marine HVAC design and engineering and professional refrigeration system conversions.

Comprehensive marine HVAC system upgrade on MV Armia Krajowa

During a scheduled dry dock maintenance period at the shipyard in Varna, the Cold World engineering team carried out extensive installation and repair work. The main challenge we faced upon boarding was a severe condenser leak in the accommodation air conditioning unit. This critical incident became the direct catalyst for a complete marine HVAC system upgrade on the MV Armia Krajowa, encompassing a thorough replacement of key components across both primary refrigeration circuits.

Technical scope of shipyard modernization works

A properly planned marine HVAC system upgrade demands engineering precision and the use of certified marine-grade materials. Our team of technicians successfully executed the following tasks within the engine room and cargo spaces:

• Accommodation AC: We dismantled the worn-out condensers and compressors. After preparing and welding new structural foundations, we installed modern shell-and-tube condensers manufactured by the renowned brand Bitzer (model K1353T). We fabricated new base plates for the compressors, performed precise system alignment, and installed new suction and discharge piping. Additionally, the refrigeration oil was replaced with Reniso Triton SEZ32, and new flexible capillary connections were routed for the control automation.

• Provision Cold Room System: For operational efficiency and space optimization, the scope of work included the challenging relocation of evaporators in both the meat and fish cold rooms. Following the physical relocation of the units, we executed new hard-brazed copper pipe connections.

• Air Handling Units (AHU): We conducted a full technical service and rigorous leak verification for the AHUs serving the Control Room, Galley, and Workshop. Across all liquid lines, the filter-drier cores were replaced with proven Danfoss DML 163 models.

Pressure testing, parameters, and system handover

Every professional marine HVAC system upgrade must conclude with strict quality assurance tests. Once the piping was assembled, a 24-hour leak test was performed using dry nitrogen under high pressure. Subsequently, a deep system evacuation was carried out down to a level of 500 microns to eliminate any residual moisture and non-condensable gases.

Ultimately, the systems were charged with eco-friendly R407C refrigerant (36 kg per primary circuit). The post-commissioning operational parameters, including a correct vapor superheat of 5 K and a condensing temperature of +37°C, confirmed full system efficiency. If your vessel is approaching a class renewal docking soon, discover our full capabilities in global marine service and major overhauls to guarantee expert support at every stage of your dry dock stay.

Comprehensive offshore HVAC system commissioning for Baltic Power

The offshore wind energy sector represents one of the most demanding operational environments for specialized refrigeration equipment. As part of the strategic Baltic Power project, the Cold World engineering team successfully executed a highly advanced technical assignment. The primary objective of our mission was professional offshore hvac system commissioning, which is absolutely critical for maintaining rigorous temperature conditions—both for sensitive technical (process) equipment and crew accommodation spaces. The extreme marine environment, high salinity, and drastically fluctuating weather conditions in the Baltic Sea leave no room for error, which is why the entire startup procedure required the utmost engineering precision from our side.

Detailed scope of technical and start-up operations

To ensure that the offshore hvac system commissioning proceeded without the slightest disruption, our certified service team carried out multi-stage preparation and testing procedures on board:

• BlueBox Process AC Systems: We conducted a full pre-operational procedure for specialized BlueBox split-type freon systems. This included dry nitrogen pressure leak testing, deep vacuuming, and precise charging with the designated refrigerant. The works were finalized with a full technological startup and strict verification of the implemented control algorithms.

• Main Air Conditioning System (Bitzer): We commissioned the central HVAC installation (general accommodation AC), powered by high-efficiency components and compressors from the renowned brand Bitzer. Our engineers performed system calibration, mechanical and electronic superheat adjustments, and rigorous performance testing under full thermal load.

• Marine Automation and Control: We meticulously inspected the correct operation of all safety systems, including pressure switches and phase loss monitors. Furthermore, we executed the full integration of the local BlueBox and Bitzer automation panels with the vessel’s overarching management system.

Certification, final testing, and operational reliability

Every expert offshore hvac system commissioning must be backed by hard data and operational measurements. The conclusion of our installation work was officially validated through rigorous operational sea trials. Thanks to precise integration, we guaranteed the absolute reliability of the refrigeration systems, even under conditions of permanent exposure to marine salt fog.

Are you managing an advanced project in the offshore wind sector? Explore our full capabilities in marine automation and control systems to ensure top-tier operational continuity for your offshore fleet.

Comprehensive marine refrigeration service during voyage

The primary task of our advanced marine refrigeration service was a full conversion of outdated systems to modern, low-GWP refrigerants, which is absolutely crucial to comply with current, stringent environmental regulations. The entire assignment aboard the MV Yeoman Bridge required perfect logistical planning from the Cold World engineering team. Why? Because all modernization stages were executed while the vessel was underway (In-Transit service) between March 8th and 20th, 2026.

Scope of modernization and system retrofits

A properly executed in-transit marine refrigeration service saves the shipowner immense costs associated with dry dock off-hire time. Our Riding Squad carried out the following scope of work:

• Provision Cold Room System: We performed a complete retrofit of main circuits No. 1 and No. 2. The worn-out Daikin compressors (model 4C552A-F) were dismantled and replaced with brand-new 4DES-7Y-40S semi-hermetic units. These new compressors were equipped with precise capacity control, cylinder head cooling fans, and reliable Henry S-5585-CE oil separators. The entire system was secured with new automation and pressure switches from Danfoss, along with a newly manufactured, dedicated control cabinet. On the valve side, modern Danfoss TE2 models fully compatible with R449A refrigerant were installed.

• General Air Conditioning (AHU): The phased-out R422D refrigerant was completely and safely recovered from the system. We performed an oil change in the Daikin 6C75-EB compressor, introducing specialized Reniso Triton SEZ 32 oil. The obsolete filter-drier housing was replaced with a modern replaceable-core model, and the evaporator coil was thoroughly cleaned.

• Control Room AC: The liquid line was upgraded by installing certified Danfoss GBC12 shut-off valves, DML 164 filter-driers, and SGH 12 sight glasses. The expansion valve was also replaced with a TE2 model featuring orifice No. 05.

Final procedures and operational testing

Every expert marine refrigeration service concludes with rigorous testing. All upgraded systems underwent dry nitrogen leak tests, followed by a multi-stage deep vacuum evacuation down to 500 microns. Ultimately, the installations were charged with the new, eco-friendly R449A refrigerant. Operational measurements confirmed highly stable equipment performance, with evaporating temperatures reaching -27°C for the provision cold rooms and +5°C for the air conditioning units.

By choosing Cold World experts, you gain guaranteed reliability under all marine conditions. Do you need similar support for your fleet? Explore our full capabilities in system conversions to schedule a comprehensive retrofit or report an emergency.