Maintenance Guides 1 min read

Diagnostics and troubleshooting: insufficient cooling capacity of industrial refrigeration systems

Technical analysis: Troubleshooting industrial cooling system insufficient capacity: heat load calculation, flow balance

1. Description of the problem and scope of application

This manual is intended for diagnosis and troubleshooting of industrial refrigeration systems, manifested by insufficient cooling capacity. The main symptoms include: increased process temperature, frequent chiller on/off cycling, reduced cooling efficiency, and increased power consumption. The manual covers the following types of equipment: industrial chillers (compression and absorption), cooling towers, dry coolers, heat exchangers (plate, shell and tube), refrigerant circulation pumping stations and refrigerant distribution systems. Classification of severity:

  • Critical: Immediate stoppage of production, risk of damage to equipment or products. Requires immediate intervention.
  • Significant: Decrease in product quality, increased operational costs, violation of the technological process. Needs urgent diagnosis.
  • Minor: Increase in power consumption, slight deviation from optimal parameters. Needs planned diagnostics and optimization.

2. Precautions

WARNING! Before performing any diagnostic or repair work, be sure to observe the following precautions:

  • LOCKOUT/TAGOUT (LOTO): Before accessing internal system components, ensure that all electrical power is disconnected and locked out in accordance with LOTO procedures (DSTU EN 1037). Check the absence of voltage using the appropriate indicator.
  • PERSONAL PROTECTIVE EQUIPMENT (PPE): Always use safety glasses/face shields, heat resistant gloves, safety shoes and overalls. When working with refrigerants, use special cryogenic gloves and full face protection.
  • STORED ENERGY: Cooling systems can contain stored energy (voltage in capacitors, refrigerant pressure, springs, heated surfaces, hot coolant). Before starting work, make sure to relieve pressure, cool surfaces and discharge electrical components.
  • REFRIGERANTS: Refrigerants can cause frostbite in contact with the skin and eyes, and can be toxic or asphyxiant in closed spaces. Provide adequate ventilation. Do not allow the refrigerant to be released into the atmosphere, use recovery stations.
  • HOT SURFACES AND LIQUIDS: Compressors, hot gas piping and some system components can be hot. Avoid contact without appropriate PPE.
  • HIGH PRESSURE: Refrigerant systems and hydraulic circuits operate under high pressure. Do not unscrew components without first relieving pressure.

3. Necessary diagnostic tools

Tool Specification/Model Measurement range Purpose
Digital contact thermometer Fluke 50 Series II, Testo 905-T2 -50°C to +250°C, accuracy ±0.5°C Measurement of liquid/pipeline surface temperature, inlet/outlet of heat exchangers, delta T.
Infrared thermometer (pyrometer) Testo 830-T2, Fluke 62 MAX+ -30°C to +500°C, accuracy ±1.5°C Fast non-contact temperature measurement of surfaces, detection of overheating/hypocooling.
Manometric station Testo 550, Fieldpiece SMAN460 High pressure: up to 60 bar; Low pressure: up to 15 bar (from -1 to 14 bar) Measurement of refrigerant suction and discharge pressure, calculation of overheating/subcooling.
Flow meter (ultrasonic/cut-in) Flexim FLUXUS F601, Siemens Sitrans FUP101 0.1 m/s to 20 m/s, DN 15-600 mm Measurement of volume flow rate of coolant in pipelines.
Vibration analyzer SKF Microlog, Fluke 805 FC Frequency range 10-1000 Hz, vibration speed 0-500 mm/s Diagnostics of the condition of rotating mechanisms (compressors, pumps, fans).
Thermal imager FLIR T540, Testo 883 -20°C to +650°C, sensitivity <0.03°C Visualization of temperature fields, detection of leaks, blockages, overheating of engines.
Multimeter (with current measurement function) Fluke 87V, KYORITSU 2012R Voltage up to 1000 V AC/DC, Current up to 1000 A AC/DC, Resistance up to 50 MΩ Measurement of electrical parameters of engines, compressors, control circuits.
Water quality analyzer Hach HQ40D, Hanna HI98194 pH: 0-14, Conductivity: 0-200 mS/cm, Turbidity: 0-1000 NTU Assessment of water composition in cooling towers and closed cooling circuits, control of corrosion and deposits.
Vacuum pump CPS VP6D, Robinair 15500 Limit vacuum: 15-25 microns Removal of moisture and non-condensable gases from the refrigeration circuit.
Refrigerant scales Fieldpiece MR45, Refco REF-METER-OCTO Accuracy ±5 g, maximum weight up to 100 kg Accurate dosing of the refrigerant when filling the system.

4. Initial review checklist

Checkpoint actions Record/Expected Result
Visual inspection Inspect all equipment (chiller, cooling tower, pumps, pipelines) for visible damage, leaks, contamination, corrosion, abnormal noises. Photos, description of defects. Leaks of oil, refrigerant, water. Visual deposits on cooling towers/heat exchangers.
Indicators of the control panel Record all current readings on the chiller control panel: compressor suction/discharge pressure, evaporator/condenser inlet/outlet water temperature, compressor current/voltage, fault status. Current values ​​(bar, °C, A, B). Compare with the manufacturer's standard.
History of accidents and warnings View the chiller control system's log of accidents and warnings for the most recent period. Pay attention to the frequency of protection activations, types of errors. Accident codes, dates, time. For example, "Low suction pressure", "High discharge pressure", "Engine overload".
Service history Get acquainted with data on the last maintenance: date, performed work (cleaning, filling, replacement of components). Date of last service. Completed works. For example, "The last cleaning of the cooling tower was 6 months ago."
Environmental conditions Record the ambient air temperature and relative humidity. For cooling towers - the presence of obstacles to the flow of air. °C, %. For example, "The air temperature is +30°C, the cooling tower is partially shaded."
Production load Estimate the current and typical heat production of the technological process served by the cooling system. Current heat production (kW/Mcal/h). Compare with the rated power of the system.

5. Systematic diagnostics (decision making scheme)

IF: The system shows insufficient cooling performance (increased temperature of the cooled process, frequent chiller cycle).

  1. Check electrical parameters and control:
    1. Measure the voltage and current of the compressor/pumps.
      • IF: The current is significantly higher than the nominal or the thermal protection is triggered.
        • PROBLEM: Compressor/pump overload.
        • CAUSES: High discharge pressure, low suction pressure (for the compressor), mechanical malfunctions, voltage deviations.
        • CHECK: Chapter 6, Phase 1.
      • IF: Current is significantly lower than rated, or the compressor/pump will not start.
        • PROBLEM: Electrical faults, control problems.
        • CAUSES: Faulty contactor, relay, low voltage, broken motor winding, sensor fault.
        • CHECK: Chapter 6, Phase 2.
    2. Check chiller controller/control system settings.
      • IF: Setpoint temperature, hysteresis, or other settings are different from design.
        • PROBLEM: Incorrect settings.
        • REASONS: Human error, unauthorized change.
        • CHECK: Compare with the manufacturer's documentation.
  2. Refrigerant circuit check (for compression chillers):
    1. Measure compressor suction and discharge pressure with a pressure gauge station.
      • IF: Suction pressure is significantly lower than normal (eg less than 3 bar for R134a at 5°C evaporating) AND discharge pressure is also low.
        • PROBLEM: Insufficient refrigerant charge.
        • REASONS: Refrigerant leakage in the system.
        • CHECK: Chapter 6, Phase 3.
      • IF: Suction pressure is significantly below normal AND discharge pressure is normal or elevated.
        • PROBLEM: Partial clogging or restriction of the suction line (filter-drier, TRV, non-return valve).
        • CAUSES: Clogging of the drier filter, incorrect setting/malfunction of the TRV, freezing of the evaporator.
        • CHECK: Chapter 6, Phase 4.
      • IF: Discharge pressure is significantly higher than normal (eg more than 18 bar for R134a at 40°C condensing).
        • PROBLEM: Condenser overload, refrigerant overcharge, non-condensable gases.
        • CAUSES: Condenser contamination (air or water), condenser fans/pumps failure, excess refrigerant, presence of air/nitrogen in the system.
        • CHECK: Chapter 6, Phase 5.
    2. Measure compressor suction superheat and condenser outlet liquid subcooling.
      • IF: Low superheat (less than 3-5°C) or high superheat (more than 8-10°C) at suction.
        • PROBLEM: Incorrect setting or TRV malfunction.
        • CAUSES: Clogging, malfunction of the thermal balloon, wrong size of the TRV.
        • CHECK: Chapter 6, Phase 4.
      • IF: Low hypothermia (less than 2-3°C) or no hypothermia.
        • PROBLEM: Insufficient refrigerant charge or liquid line blockage.
        • CAUSES: Leakage, clogging of the filter-drier.
        • CHECK: Chapter 6, Phase 3.
  3. Refrigerant circuit check (water, glycol):
    1. Measure the temperature of the refrigerant at the inlet and outlet of the evaporator/process consumer.
      • IF: Delta T (inlet temperature - outlet temperature) is significantly lower than the design value (for example, less than 3-5°C at nominal load).
        • PROBLEM: Low refrigerant flow through the evaporator/consumer.
        • CAUSES: Partial clogging of the heat exchanger, malfunction/low performance of the pump, clogging of filters, air jams.
        • CHECK: Chapter 6, Phase 6.
      • IF: Evaporator inlet temperature is significantly higher than normal.
        • PROBLEM: Excessive thermal load on the system or problems with heat transfer from the technological process.
        • REASONS: Increase in production load, malfunction of control valves on consumers, contamination of heat exchangers of consumers.
        • CHECK: Chapter 6, Phase 7.
    2. Measure the refrigerant flow rate using a flow meter.
      • IF: The flow rate is much lower than the design one.
        • PROBLEM: Low refrigerant flow.
        • REASONS: As in clause 3.a.
        • CHECK: Chapter 6, Phase 6.
    3. Check the cleanliness of coolant filters and heat exchangers.
      • IF: Filters are dirty, heat exchangers have visible deposits.
        • PROBLEM: Clogging of the coolant circuit.
        • CAUSES: Insufficient filtration, lack of chemical water preparation, corrosion.
        • CHECK: Chapter 6, Phase 6.
  4. Checking the cooling water circuit (for condenser water-cooled chillers, cooling towers):
    1. Measure the water temperature at the inlet and outlet of the chiller condenser.
      • IF: Delta T is significantly less than the design value (for example, less than 3-5°C).
        • PROBLEM: Low flow of cooling water through the condenser.
        • REASONS: As in point 3.a for coolant, but applies to cooling water.
        • CHECK: Chapter 6, Phase 8.
      • IF: The water temperature at the inlet to the condenser is significantly higher than the design temperature.
        • PROBLEM: Insufficient cooling in cooling room/dry cooler.
        • CAUSES: Contamination of the cooling tower (nozzles, sprinklers), failure of cooling tower fans, low water flow through the cooling tower, excessive heat load.
        • CHECK: Chapter 6, Phase 9.
    2. Check cooling room/dry cooler for cleanliness.
      • IF: Visible dirt, deposits, blocked nozzles, fans not working.
        • PROBLEM: Decreased cooling efficiency in cooling room/dry cooler.
        • CAUSES: Lack of regular maintenance, hard water, biological contamination.
        • CHECK: Chapter 6, Phase 9.

6. Matrix of malfunctions and causes

Symptom Probable causes (ranked by probability) Diagnostic test Expected result when confirming the cause
Phase 1: Compressor/Pump Overload (High Current, Protection Trip)
  1. High injection pressure (90%)
  2. Mechanical malfunctions of the compressor/pump (8%)
  3. Supply voltage deviation (2%)
 Injection pressure measurement, vibration analysis, voltage measurement.
  1. Injection pressure >18 bar (R134a)
  2. Vibration speed >7.1 mm/s (ISO 10816-1 for large machines)
  3. Voltage higher/lower than nominal ±10%
Phase 2: Electrical faults (compressor/pump not starting, low current)
  1. Contactor/relay fault (40%)
  2. Motor winding failure (30%)
  3. Sensor failure (20%)
  4. Low supply voltage (10%)
 Checking the contactor with a multimeter, measuring the resistance of the motor windings, checking the sensor signals.
  1. No commutation, high contact resistance
  2. Open circuit or inter-turn short circuit (significant resistance deviation)
  3. No signal, incorrect indicators
  4. Voltage lower than nominal >10%
Phase 3: Insufficient refrigerant charge (low suction pressure, low subcooling)
  1. Refrigerant leakage (95%)
  2. Incorrect filling during installation/maintenance (5%)
 Measurement of pressures and temperatures, use of a refrigerant leak detector, visual inspection for the presence of oil traces. Suction pressure <3 bar (R134a), subcooling <2°C. The leak detector is working.
Phase 4: Clogging/restriction in the refrigerant suction circuit (low suction pressure, high superheat)
  1. Dryer filter clogging (50%)
  2. Malfunction/incorrect setting of TRV (40%)
  3. Partial icing of the evaporator (10%)
 Measurement of the pressure drop on the filter-drier, visual inspection of the TRV and evaporator, overheating control.
  1. Pressure drop >0.2 bar on the filter
  2. Unstable overheating >10°C or low <3°C
  3. Ice on the surface of the evaporator
Phase 5: Condensation problems (high discharge pressure, low subcooling)
  1. Condenser contamination (60%)
  2. Condenser fan/pump failure (25%)
  3. Excessive refrigerant charge (10%)
  4. The presence of non-condensable gases (5%)
 Visual inspection of the condenser (ribs, nozzles), checking the operation of fans/pumps, measuring temperature/pressure.
  1. Visible deposits, blocked fins/nozzles
  2. Fans not working/low speed. Injection pressure >18 bar.
  3. Hypothermia <2°C. Injection pressure >18 bar.
  4. Unstable pressures, excessive injection temperature.
Phase 6: Low Refrigerant Flow (Low Delta T, Low Flow)
  1. Clogging of coolant filters (50%)
  2. Malfunction/low performance of the pump (30%)
  3. Clogging of the evaporator/consumer heat exchanger (15%)
  4. Air jams in the system (5%)
 Pressure drop measurement on filters, flow measurement, visual inspection of the pump and heat exchanger.
  1. Pressure drop >0.5 bar on the filter
  2. Consumption <80% of the design, pump noise
  3. Visible deposits in heat exchanger, low delta T
  4. Air bubbles in the expansion tank, noise in the pipes
Phase 7: Excessive thermal load on the system (the temperature of the inlet to the evaporator is higher than normal)
  1. Increase in production load (60%)
  2. Malfunction of control valves on consumers (30%)
  3. Contamination of consumer heat exchangers (10%)
 Control of the technological process, checking the operation of control valves, visual inspection of heat exchangers of consumers.
  1. The current thermal load > the nominal capacity of the chiller
  2. The valve does not close completely or does not regulate the flow
  3. Delay, reduced delta T on consumer
Phase 8: Low flow of cooling water through condenser (low delta T on condenser)
  1. Clogging of cooling water filters (50%)
  2. Malfunction/low performance of cooling tower pump (30%)
  3. Condenser heat exchanger clogging (15%)
  4. Air jams in the system (5%)
 Pressure drop measurement on filters, flow measurement, visual inspection of the pump and condenser. As in Phase 6, but applies to the cooling water circuit.
Phase 9: Insufficient cooling in the cooling tower/dry cooler (high condenser water temperature)
  1. Contamination of sprinklers/nozzles of the cooling tower (40%)
  2. Malfunction/insufficient speed of cooling tower fans (30%)
  3. Air short circuit in the cooling tower (20%)
  4. Low water flow through the cooling tower (10%)
 Visual inspection of the cooling tower, checking the operation of the fans (current, speed), measuring the temperature of the wet bulb.
  1. Deposition, biological pollution, uneven distribution of water
  2. Fans do not work, reduced rotation speed, high motor current
  3. Hot air from the outlet of the cooling tower is recirculated to the inlet
  4. Water consumption through the cooling tower <80% of the design

7. Analysis of the root causes of malfunctions

7.1. Contamination of the heat exchanger (condenser/evaporator/cooling room)

Explanation: Pollution can be caused by scale deposits (calcium carbonate, magnesium), corrosion products (metal oxides), biological deposits (algae, slime) or mechanical impurities (sand, dirt). This leads to the formation of an insulating layer on the heat exchange surfaces, which significantly reduces the heat transfer coefficient.

How to confirm:

  • Measuring the pressure drop on the heat exchanger (for water circuits) — a significant increase (more than 0.5 bar) indicates internal clogging.
  • Visual inspection (after dismantling or through inspection hatches) — presence of visible deposits, scale, biological growths.
  • Measuring the temperature of the surface of the heat exchanger with a thermal imager — detecting cold or hot zones, indicating an uneven flow distribution or heavy contamination.

Potential damage: Decreased cooling performance of the system, increased energy consumption, increased compressor discharge pressure (for a dirty condenser), which leads to its overload, overheating and premature wear. In the long term, the destruction of the heat exchanger material due to local overheating/subcooling and corrosion under deposits.

7.2. Insufficient refrigerant charge (leakage)

Explanation: A reduction in the amount of refrigerant in the system is usually the result of leaks due to leaky connections, seals, cracks in piping or equipment defects. An insufficient amount of refrigerant disrupts the cooling cycle, reducing its efficiency.

How to confirm:

  • Measuring suction and discharge pressures - both pressures will be lower than normal and the difference between them may be small.
  • Measurement of superheat at the compressor suction — significantly increased superheat (more than 8-10°C).
  • Condenser output subcooling measurement — low subcooling (less than 2-3°C) or no subcooling.
  • Using an electronic refrigerant leak detector to locate the leak.
  • Visual search for oil traces on pipelines and components (refrigerant carries oil with it).

Potential damage: Decrease in cooling capacity, overheating of the compressor due to insufficient cooling of the engine with refrigerant, damage to the compressor due to oil starvation (refrigerant transfers oil), increased electricity consumption, risk of environmental damage.

7.3. Low coolant/cooling water flow

Explanation: Reduction of volume flow of coolant through the evaporator or cooling water through the condenser. Can be caused by clogged filters, malfunction of the circulation pump (wear, clogged impeller), air jams in the system, improper opening of the shut-off valve, or deposits inside the pipelines/heat exchangers.

How to confirm:

  • Measurement of coolant/water flow using a flow meter — the indicators are significantly lower than the design ones.
  • Evaporator/condenser pressure drop measurement is significantly lower than design (if flow is low) or significantly higher (if exchanger is clogged).
  • Delta T measurement (inlet/outlet temperature) is significantly lower than design (less than 3°C at rated load).
  • Check Pump Inlet and Outlet Pressure - A faulty pump may have low outlet pressure.
  • Visual inspection of filters — visible contamination.

Potential damage: Decreased heat exchange efficiency, evaporator icing (for low refrigerant flow), increased compressor discharge pressure (for low cooling water flow), cavitation in pumps, increased energy consumption.

7.4. Non-condensable gases in the system

Explanation: The presence of air, nitrogen or other gases that do not condense at the operating temperatures and pressures of the refrigeration cycle. These gases usually enter the system during installation, repair (insufficient vacuuming) or through leaks in low pressure areas. They accumulate in the condenser, reducing the effective heat exchange surface.

How to confirm:

  • High discharge pressure of the compressor without a proportional increase in the condensing temperature (according to the tables of saturated vapors).
  • Low subcooling of the refrigerant at the condenser outlet.
  • Pulsation of injection pressure.
  • Slow recovery of pressure after compressor shutdown (when the system equalizes).

Potential damage: A significant increase in discharge pressure, which leads to compressor overload, increased power consumption, activation of high-pressure protective devices, increased compressor wear.

8. Step-by-step troubleshooting procedures

8.1. Procedure for cleaning heat exchangers

  1. SAFETY: Apply LOTO procedures to the chiller and pumps of the appropriate circuit. Release the pressure from the water circuit, drain it.
  2. Mechanical cleaning (for shell-and-tube or plate dismountable heat exchangers):
    1. Dismantle the end caps of the shell-and-tube heat exchanger or disassemble the plate package.
    2. Remove mechanical contamination with brushes (for pipes) or special washing machines (for plates).
    3. Check the integrity of the seals. Replace damaged ones.
    4. Assemble the heat exchanger, tightening the bolts with the torque specified by the manufacturer (for example, 20-30 Nm for shell and tube).
  3. Chemical cleaning (for all types, especially non-dismountable):
    1. Isolate the heat exchanger from the rest of the system.
    2. Connect the pump to circulate the washing solution.
    3. Fill the heat exchanger with a special chemical solution (such as an acid solution for scaling or a biocide for biological deposits) according to the chemical manufacturer's instructions.
    4. Circulate the solution for the recommended time (eg 2-6 hours) with pH control.
    5. Drain the used solution (dispose in accordance with environmental regulations).
    6. Thoroughly rinse the heat exchanger with clean water until the pH is neutral.
  4. Verification: Start the system. Check the pressure drop on the heat exchanger (it should be within the normal range, for example, 0.1-0.2 bar). Control the temperatures.

8.2. The procedure for finding leaks and refilling refrigerant

  1. SECURITY: Apply LOTO procedures. Use PPE (cryogenic gloves, face protection).
  2. Leak search:
    1. With the help of an electronic leak detector, carefully examine all connections, valves, soldering points, welds, seals, sensor attachment points.
    2. Use a soapy solution to visualize small leaks.
    3. If the leak is significant, restore the tightness of the system (soldering, replacement of seals, repair or replacement of damaged components).
  3. Evacuation:
    1. Connect the vacuum pump to the service ports of the system through the gauge station.
    2. Vacuum the system until a deep vacuum is reached (250-500 microns or less than 0.5 mbar).
    3. Close the valves of the manometric station and turn off the pump. Monitor the increase in pressure for 15-30 minutes. A pressure increase of more than 50 microns indicates the presence of a leak or moisture in the system. Repeat vacuuming or leak detection as necessary.
  4. Refilling the refrigerant:
    1. Connect the cylinder with the refrigerant to the manometric station, install the cylinder on the scale.
    2. Fill in the refrigerant in the liquid phase (through the liquid line) until reaching the required mass according to the chiller nameplate (accuracy ±50 g). If necessary, it is allowed to refuel in the gas phase through the suction line in small portions while the compressor is running, constantly monitoring overheating.
    3. CAUTION: Overfilling can cause excessive pressure and compressor overload.
  5. Verification: Start the chiller. Control pressures, temperatures, overheating (5-7°C) and hypothermia (4-6°C). Check the system with a leak detector again.

8.3. Coolant/cooling water flow recovery procedure

  1. SAFETY: Apply LOTO procedures to pumps and any electrical circuit components.
  2. Checking and cleaning the filters:
    1. Isolate the filter section, drain the pressure.
    2. Open the filter housing, remove the filter element.
    3. Clean or replace the filter element.
    4. Assemble the filter, making sure the gaskets are installed correctly.
  3. Checking the pump:
    1. Visually inspect the pump for leaks, noises, and vibrations.
    2. Check the pump inlet and outlet pressure.
    3. If the pump is running but the outlet pressure is low, the impeller may be clogged (requires disassembly and cleaning) or worn.
    4. Check the electrical parameters of the pump (current) - a significant deviation indicates a malfunction.
    5. Replace the faulty pump or its components (bearings, seals).
  4. Removing air plugs:
    1. Open all air valves (vents) at the upper points of the system.
    2. Maintain system pressure until air stops escaping and only water comes out of the valves.
    3. Ensure proper operation of automatic air vents.
  5. Verification: Start the system. Measure refrigerant/water flow, pressure drop across heat exchangers, and delta T. All readings should be within normal limits.

9. Precautions

The root cause Prevention strategy Monitoring method Recommended interval
Contamination of the heat exchanger Regular chemical/mechanical cleaning, water preparation, use of filters with the appropriate degree of filtration. Pressure drop control on the heat exchanger, water quality analysis (pH, hardness, conductivity, content of suspended substances), visual inspection. Quarterly (water analysis), once every 6-12 months (cleaning), weekly (pressure drop).
Insufficient refrigerant charge (leakage) Regular checking for tightness, maintenance of seals, minimization of vibrations. Daily monitoring of pressures/temperatures, weekly visual inspection, use of electronic leak detectors. Weekly (visual), once every 3-6 months (leak detector).
Low coolant/cooling water flow Regular cleaning of filters, maintenance/replacement of pumps, monitoring of pipelines. Pressure drop control on filters, flow measurement, pump current monitoring, vibration analysis of pumps. Weekly (filters), monthly (consumption), once every 6-12 months (vibration/pump maintenance).
Non-condensable gases in the system High-quality vacuuming of the system during installation/repair, elimination of leaks. Pressure/temperature control (ratio), liquid subcooling. Monthly (parameter control).
Condensation/cooling tower issues Regular cleaning of the cooling tower (sprinklers, nozzles), maintenance of fans/pumps of the cooling tower. Visual inspection, wet bulb temperature control, fan/pump motor current monitoring. Monthly (visual), once every 3-6 months (cleaning).

10. Spare parts and components

Component description Specification/type When to replace Category UNITEC
Refrigerant filter-drier Size according to chiller performance (e.g. DML 164) With a significant pressure drop (>0.2 bar), after major repairs of the refrigerant system, with the appearance of moisture in the system. Refrigeration automation
Thermoregulating valve (TRV) Type and performance according to chiller (e.g. Danfoss TGE, Sporlan S-series) In case of unstable overheating, clogging, thermoball malfunction, mechanical damage. Refrigeration automation
Sealing (for heat exchangers, valves) Material (EPDM, NBR), size according to component In case of leaks, during the dismantling of components, after chemical cleaning. Sealing materials
Pressure/temperature sensors Measurement range, signal type (4-20mA, 0-10V) In case of incorrect readings, failures in the operation of automation. Measuring devices
Circulation pump (for coolant/cooling water) Productivity (m³/h), head (m), type (centrifugal, multi-stage) In case of reduced performance, increased vibration/noise, mechanical damage, wear and tear. Pumping equipment
Filter elements for water/coolant Degree of filtration (μm), size, material In case of contamination, reduced flow, increased pressure drop. Filtration systems
Refrigerant Type (R134a, R407C, R410A) If refueling or full refueling is necessary after repair. Consumables
Contactor/thermal relay Rated current, coil voltage, size In the event of a malfunction of the electrical part, activation of protection for no reason, sticking of contacts. Electrical components
Bearings for compressor/pump/fan motors Size, accuracy class (e.g. SKF 6205-2RS1) With increased vibration, noise, overheating, significant wear and tear. Mechanical components
Electric motor (compressor/pump/fan) Power (kW), speed (rpm), voltage (V) In case of broken windings, inter-turn shorting, severe overheating, mechanical damage. Electric motors

Look for these and other required components in the UNITEC catalog: www.unitecd.com/e-catalog/

11. Links

  • DSTU EN 378-1:2018 (EN 378-1:2016, IDT) Refrigeration systems and heat pumps. Safety and environmental requirements. Part 1. Basic requirements, definitions, classifications and selection criteria.
  • ISO 5149:2014 Refrigerating systems and heat pumps — Safety and environmental requirements.
  • EN 1037:1995+A1:2008 Safety of machinery — Prevention of unexpected start-up.
  • ISO 10816-1:1995 Mechanical vibration — Evaluation of machine vibration by measurements on non-rotating parts — Part 1: General guidelines.
  • Operation and maintenance manuals from equipment manufacturers (OEM documentation).
  • UNITEC's internal refrigeration maintenance manuals.

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