Air-Cooled Chiller Installation Method Statement

What This Chiller Installation Method Statement Covers

The complete working procedure for the installation of an air-cooled screw compressor chiller on a building services project, from delivery to handover. It is written in the sequence that a site team would work in and is designed to be customized for a specific project and submitted as such.

Each project is unique and has its own specification, approved drawings and authority requirements. Those take precedence over anything here. If a figure is provided in this document, use it to guide only, and replace with the manufacturer’s machine installation manual.

Scope of Work

This method covers:

• Receipt, inspection, offloading and storage of the chiller and its ancillaries
• Verification of the plinth, foundation and structural provision
• Rigging, lifting and final positioning on anti-vibration mounts
• Chilled water pipework connections, strainers, valves and instrumentation
• Electrical supply termination, earthing and control wiring
• Pressure testing, flushing, chemical cleaning and filling
• Pre-commissioning checks and witnessed commissioning
• Handover documentation and training

It excludes the design of the chilled water system, the structural design of the plinth, the incoming electrical supply up to the isolator, and the water treatment specification. Those are the responsibility of the designer and are assumed to be approved before this work begins.

Applicable Standards and Project Documents

Name the actual editions applicable to your project. As a typical set:

• Manufacturer’s installation, operation and maintenance manual for the specific chiller model — this governs above all else
• ASHRAE Handbook, HVAC Systems and Equipment, for chilled water system practice
• ASHRAE Standard 15, Safety Standard for Refrigeration Systems
• ASME B31.9, Building Services Piping, or the piping code named in the specification
• The national electrical code applicable to the project, for supply, protection and earthing
• Approved shop drawings, equipment submittals and the project specification
• Project HSE plan, lifting plan and permit-to-work procedures

Responsibilities

Materials and Equipment

• Air-cooled screw chiller as per approved submittal, with matching serial and model number
• Anti-vibration mounts — spring or rubber-in-shear as specified, sized for the operating weight distribution given by the manufacturer
• Flexible connectors on chilled water supply and return, rated for system pressure and temperature
• Butterfly or gate isolation valves, strainer with the specified mesh, balancing valve, drain and vent points
• Thermometers and pressure gauges at inlet and outlet, with pockets and isolation cocks
• Flow switch and, where specified, differential pressure switch
• Pipe supports, guides and anchors to the approved support drawing
• Insulation with vapour barrier for chilled water lines, complete at supports
• Cable, glands, cable tray and earthing conductors as per approved electrical submittal

Delivery, Inspection, and Storage

Inspect on arrival, before offloading, and record the result.

• Check the model, serial number and capacity against the approved submittal. A mismatch found after the unit is set is expensive to correct
• Check for transit damage to the coil block, panels, control enclosure and pipework connections. Photograph anything suspect before it is moved
• Verify the shock and tilt indicators if fitted, and record their state on the delivery note
• Confirm the refrigerant holding charge pressure where the machine is shipped with one. A unit that has lost its charge in transit has a leak that must be found before installation, not after
• Store on level ground clear of construction traffic, with panels closed and the control enclosure protected from water ingress
• Keep loose items — flow switch, remote sensors, documentation, keys — in secure storage and log them, since these are the parts that disappear on site

Pre-Installation Requirements

Do not begin setting the machine until each of these is confirmed and signed off.

• Concrete plinth cast, cured and dimensionally correct against the approved drawing, with level checked in both directions
• Structural approval in place where the chiller sits on a roof or an elevated slab, confirming the operating weight including water is within the allowance
• Clearances around the unit verified against the manufacturer’s requirement — air-cooled condensers need unobstructed intake on all coil faces and clear discharge above
• Access route surveyed and clear, including gate widths, corner radii, ramp gradients and any temporary protection of finished floors
• Lifting plan approved, crane position and outrigger loading agreed with the structural engineer
• Electrical supply available, cable pulled and terminated at the isolator, and the supply proven dead until connection
• Chilled water pipework installed to within the final connection, flushed and ready

The clearance check is the one most often skipped. An air-cooled chiller starved of intake air recirculates its own discharge, the condensing temperature climbs, and the machine loses capacity and trips on high pressure in the exact conditions it was bought for. Verify the manufacturer’s figures against the actual plant room or roof layout before the unit is set, not after.

Rigging, Lifting and Positioning

1. Hold the pre-lift briefing. Lifting supervisor, crane operator, banksman and the installation crew. Confirm the exclusion zone and the communication method.
2. Use the designated lifting points only. Screw chillers have specified lugs or base slots. Slinging under the frame or around the coil block distorts the base and damages the condenser.
3. Use spreader beams where the manufacturer requires them so the sling angle does not induce compression across the frame.
4. Keep the unit level during the lift. Screw compressors carry an oil charge; excessive tilt during handling moves oil into the discharge line.
5. Set down onto the anti-vibration mounts in the positions shown on the manufacturer’s weight distribution drawing. Corner loads on a chiller are rarely equal, and mounts sized on total weight divided by four will settle unevenly.
6. Level the unit in both axes and check against the manufacturer’s tolerance. Adjust the mounts rather than packing under the frame.
7. Confirm the final position against the approved layout, including service access to the control panel, compressor and coil face.

Chilled Water Piping

• Support the pipework independently. No load from the piping may be carried by the chiller nozzles — this is the most common cause of nozzle damage and warranty rejection
• Install flexible connectors at supply and return to accommodate movement on the anti-vibration mounts
• Fit the strainer in the return line ahead of the evaporator, with the specified mesh, and with room to withdraw the basket
• Install isolation valves both sides so the evaporator can be isolated without draining the system
• Provide drain points at the low side and air vents at every high point on the chiller connections
• Install the flow switch in a straight run to the manufacturer’s requirement, in the correct orientation and flow direction. A flow switch fitted the wrong way round or too close to a fitting will not protect the evaporator
• Fit thermometer pockets and pressure gauges at inlet and outlet, positioned so they can be read from standing level
• Insulate and seal the vapour barrier continuously, including at supports and valve bodies. A break in the vapour barrier on a chilled line condenses inside the insulation and corrodes the pipe out of sight

Electrical Connections and Earthing

• Verify supply voltage, phase rotation and available fault level against the machine nameplate before energising. Screw compressors are direction-sensitive and reverse rotation will damage the compressor within seconds
• Confirm cable size and protection against the manufacturer’s maximum overcurrent protection and minimum circuit ampacity figures, not against the nominal motor rating
• Terminate to the manufacturer’s torque values and record them
• Earth the frame and the control panel to the project earthing scheme, and verify continuity
• Segregate control and power wiring, and screen analogue signals where the run is long or shares a route with power
• Terminate interlocks correctly — chilled water pump status, flow switch and any remote enable. A chiller allowed to start without proven flow will freeze the evaporator
• Leave the supply isolated and locked off until commissioning

Controls and Instrumentation

• Install remote sensors in accordance with the manufacturer’s requirement for immersion depth and location
• Terminate the BMS interface — volt-free contacts or serial connection as specified — and record the point list
• Verify each hardwired interlock physically, by operating the device and confirming the response at the panel
• Confirm the control strategy with the commissioning engineer before start-up, including setpoints, staging and any sequencing with other machines

Pressure Testing, Flushing and Filling

1. Isolate the chiller and pressure test the pipework separately at the specified test pressure. Do not subject the evaporator to a test pressure above the manufacturer’s rating.
2. Flush the system with the chiller isolated and bypassed. Construction debris driven through an evaporator will block tubes, and the damage is not recoverable on site.
3. Chemically clean and passivate as specified, then flush again until the water sample meets the acceptance criteria.
4. Clean the strainer after flushing and again after the first hours of operation.
5. Fill and vent the system, confirming all high points are vented and the expansion vessel is charged to the correct pressure.
6. Open the chiller isolation valves only once the water quality has been accepted.

Pre-Commissioning Checks

• Unit level, mounts correctly loaded and any shipping restraints removed. Transit brackets left in place defeat the vibration isolation entirely
• All panels, guards and coil protection in place
• Condenser coils clean and free of construction dust. A fouled coil raises condensing pressure from the first day of operation
• Refrigerant circuit pressures consistent with ambient, with no evidence of loss
• Oil level within the sight glass range and oil heaters energised for the period the manufacturer specifies before start — commonly several hours, and skipping it risks liquid slugging on start
• Water flow established and within the design range, and the flow switch proven by isolating flow and confirming the trip
• Supply voltage and phase rotation confirmed at the machine terminals
• Control setpoints entered and interlocks proven

Commissioning

First start-up is carried out by the manufacturer’s authorised technician. Attempting it without them will normally void the warranty.

• Witness the start sequence and record suction and discharge pressures, saturated temperatures, superheat, subcooling and oil pressure differential
• Record chilled water flow, inlet and outlet temperatures and the resulting duty, and compare against the selection
• Verify capacity control operates through its range and that staging and unloading behave as designed
• Verify each safety device operates — high pressure, low pressure, freeze protection, flow proving, phase failure
• Confirm BMS points read correctly at the head end, in engineering units, in both directions
• Run the machine at stable load for the duration required by the specification and log the readings

Health and Safety

• Lifting operations under an approved plan with an appointed person, exclusion zones and no personnel beneath a suspended load
• Permit to work for hot works, confined space, working at height and electrical isolation as applicable
• Refrigerant handling only by certified personnel, with attention to displacement risk in enclosed plant rooms and the requirements of ASHRAE 15 or the local equivalent
• Lock-out tag-out during all electrical work, with proving dead before touching
• Chemical cleaning under the safety data sheet, with the right PPE and disposal route
• Roof access controls including edge protection where the plant is at height

Handover Documentation

• Approved material submittal, delivery notes and inspection records
• Signed inspection and test plan with all witness points closed
• Pressure test, flushing and water quality certificates
• Manufacturer’s start-up report and warranty registration
• Commissioning records with logged readings at stable operation
• As-built drawings, operation and maintenance manuals, and the spares list
• Record of operator training delivered

Common Mistakes on Chiller Installations

• Insufficient condenser clearance. The single most common cause of a chiller that never makes its rated capacity
• Pipework weight on the nozzles. Damages the evaporator connection and is usually excluded from warranty
• Flushing through the evaporator. Debris in the tubes cannot be cleaned out on site
• Shipping restraints left fitted. The vibration isolation does nothing and the structure carries the excitation
• Oil heaters not energised for long enough before first start. Risks liquid refrigerant in the oil and compressor damage on start
• Flow switch fitted too close to a bend or valve. It will either fail to prove flow or prove flow that is not there
• Phase rotation unchecked. A screw compressor run backwards is damaged in seconds

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