Service / Precision Cooling Maintenance
CDW CRAC ServicingCondenser Water Precision Cooling
Direct answer
A CDW CRAC unit has its own compressor, like a DX unit, but rejects heat into a condenser water loop rather than to an outdoor air-cooled condenser. That loop usually runs to a cooling tower. Servicing therefore covers two things at once: the unit itself, and the water side, where scale, biofilm and corrosion quietly destroy heat transfer. Quarterly professional service is the recommended interval.
Indigi Power and Cooling services CDW CRAC systems across Australia from $720 ex GST metro for a one-off inspection with a written report, covering Vertiv Liebert, Schneider Uniflair, STULZ and legacy Emerson platforms. Call 1800 046 344.
The thing most owners miss
The unit is notthe regulated part
Public health law in Australia does not regulate your CRAC unit. It regulates the cooling tower that unit depends on. That distinction sounds academic until you notice that in most buildings the CRAC units and the cooling tower are maintained by two different contractors who have never spoken to each other.
Cooling tower systems are covered by AS/NZS 3666, and in New South Wales and Victoria they must additionally be registered with the local council, operated under a documented risk management plan, sampled routinely for Legionella, and independently audited each year. Other states impose their own requirements under public health legislation. Obligations are periodically updated, so the current position for your state is worth confirming rather than assuming.
The practical failure mode is a gap rather than a breach. The mechanical contractor services the CRAC units and reports the room is fine. The water treatment provider doses the tower and reports the water is compliant. Nobody is looking at the number that connects them, which is how much the condenser water circuit has degraded and what that is doing to the units drawing off it.
We service the unit and read the water side at the same visit, then say plainly in the report whether the loop is holding up its end. Where a tower is involved we will coordinate with whoever maintains it rather than stopping at the isolation valve.
Indigi Power and Cooling is Indigenous and Veteran-owned, Supply Nation and ICN Gateway registered. We are vendor agnostic, so we service the units you already own regardless of who supplied them.
Not every water-cooled unit is the same
Cooling toweror closed glycol loop
Cooling
tower
- Water is evaporated to reject heat, so it is open to air
- Most efficient option, particularly at scale
- Make-up water and blowdown continuously required
- Scale, biofilm and airborne contamination all apply
- Registration, risk management plan and auditing apply
- Large data halls, hospitals, industrial plant
Glycol
loop
- Water and glycol sealed in a closed circuit
- Heat rejected through an outdoor dry cooler
- No evaporation, so no make-up water and no drift
- Corrosion inhibitor and glycol concentration to maintain
- No cooling tower, so no Legionella registration obligation
- Smaller halls, colder climates, water restricted sites
Know which one you have
DX, CDW and CHW compared
All three are precision cooling units. What separates them is where the heat goes, and that single difference drives everything about how they are serviced and who has to be licensed to do it.
| System type | Heat rejection method | What defines the servicing |
|---|---|---|
| DX, direct expansion | Refrigerant circuit to an outdoor air-cooled condenser | Refrigerant handling, which requires an ARCtick licence. Condenser coil cleaning and charge integrity dominate the visit |
| CDW, condenser water | Compressor in the unit, heat rejected into a condenser water loop, usually to a cooling tower | Two systems at once. Refrigerant work under ARCtick plus the water side, where fouling and water quality set the unit's real capacity. Cooling tower compliance applies to the loop |
| CHW, chilled water | Chilled water from a central chiller plant, no compressor in the unit | Hydronic. Valve stroke and seating, flow and delta T, coil condition and strainers. No refrigerant in the room at all |
If you are not certain which you have, the quickest test is whether the unit contains a compressor and whether the pipework leaving it carries refrigerant or water. We cover the distinction in more depth on the DX, CHW and CDW explainer, and service the other two types on our DX servicing and CHW and CRAH maintenance pages.
From site
A serviced comms room with the cooling units in line beside the racks. Rooms like this are where the split responsibility problem shows up most clearly: the units are labelled and scheduled, and the loop feeding them is somebody else's contract.
Note the units are individually numbered. That matters more than it looks. A maintenance record that says "CRAC serviced" without identifying which unit is close to useless for trending, and trending is the only way water side degradation becomes visible before it becomes expensive.
The water side
What fouling actually costs you
A CDW unit fails slowly and expensively rather than suddenly. Every one of these problems presents the same way at first: the room is a little warmer than it used to be and the unit runs longer to hold setpoint.
| Problem | What it does | What we do about it |
|---|---|---|
| Scale on the condenser tubes | Mineral deposit acts as insulation exactly where heat needs to move. Head pressure climbs, the compressor works harder for less cooling, and energy consumption rises well before capacity visibly drops | Measure the approach temperature between condenser water and refrigerant. A widening approach is the earliest reliable evidence. Chemical clean or mechanical tube clean depending on severity |
| Biofilm and biological fouling | A thin biological layer insulates far more effectively than its thickness suggests, and in an open tower circuit it also carries a public health dimension | Review biocide dosing and water test results against the treatment regime, inspect accessible surfaces, and flag to the water treatment provider where the loop is out of specification |
| Corrosion and dissolved solids | Attacks tubes, pipework and the heat exchanger. Eventually causes leaks, and in the meantime the corrosion products themselves foul surfaces downstream | Check inhibitor levels, cycles of concentration and pH against the treatment plan. Inspect strainers, which usually reveal what is circulating before anything else does |
| Low or unbalanced water flow | Starves the condenser. Head pressure rises and the unit may trip on high pressure, which is often misdiagnosed as a refrigerant fault | Measure flow rate and differential pressure across the condenser, test isolation valves, and check strainers and the pump set serving the loop |
| Water regulating valve out of adjustment | This valve modulates condenser water flow to hold head pressure. When it sticks or drifts the unit either wastes water and pumping energy or runs at excessive head | Test valve modulation across the operating range and verify actuator response, then reset to specification. A frequently overlooked component that is cheap to correct |
| Evaporator coil fouling, air side | Reduces airflow and heat pick-up from the room. Compounds any water side problem, so the two together degrade capacity faster than either alone | Coil inspection and clean, filter replacement, and airflow measured rather than assumed. Coil condition photographed and recorded at each visit |
Compliance
Cooling tower obligations
Where your CDW loop rejects heat through a cooling tower, these obligations attach to the tower system. They are the building owner's or occupier's responsibility, not the CRAC contractor's, but they affect how the whole system has to be run and documented. Requirements vary by state and are periodically updated, so treat this as orientation rather than legal advice and confirm the current position for your jurisdiction.
| Obligation | What it involves in practice |
|---|---|
| Governing standard | AS/NZS 3666 covers air-handling and water systems of buildings for microbial control, spanning design and installation through to ongoing operation and maintenance of cooling water systems |
| Registration | In New South Wales and Victoria, cooling tower systems must be registered with the local council. Registration identifies the system and the responsible person |
| Risk management plan | A documented water risk management plan covering the system, its hazards, the controls in place and who is accountable. This is the document an auditor or inspector asks for first |
| Routine sampling | Regular laboratory sampling for Legionella and general microbial load, at intervals set by the applicable regulation, with results retained |
| Water treatment | A dosing regime for biocide, scale inhibitor and corrosion inhibitor, monitored and adjusted, with records kept of what was dosed and when |
| Physical inspection and cleaning | Inspection and cleaning of the tower itself including fill media, basin and drift eliminators, on the schedule the regulation or the risk plan sets |
| Independent auditing | In New South Wales and Victoria, an annual audit by an independent auditor, with the report retained and made available on request |
| Record keeping | Retained records covering testing, dosing, inspections, maintenance and corrective actions, held for the period the regulation specifies |
On a closed glycol loop with a dry cooler there is no evaporative tower, so none of the registration, sampling or auditing obligations above apply. If you are not sure which arrangement your building has, that is worth establishing before your next audit rather than during it.
The checklist
What a CDW service covers
Published in full, so you can compare it against what you are currently paying for. The items that produce a recorded number are the ones worth checking your incumbent actually performs.
| Service item | Detail |
|---|---|
| Condenser water loop inspection | Flow rate measurement, differential pressure across the condenser, pipework condition assessment and isolation valve testing |
| Approach temperature check | Condenser water to refrigerant approach measured and trended against previous visits. The earliest reliable indicator that the water side is fouling |
| Cooling coil cleaning and inspection | Evaporator coil inspection and cleaning to restore heat transfer efficiency, with coil condition recorded and photographed |
| Condenser water valve and actuator checks | Water regulating valve modulation tested across its range, actuator response verified, isolation valve condition assessed |
| Water treatment verification | Condenser water quality reviewed, biocide and inhibitor levels checked against the treatment regime, and Legionella risk status noted on the report |
| Refrigerant circuit checks | Head and suction pressures, superheat and subcooling, and leak inspection. Carried out under ARCtick licence, with charge recorded |
| Air filter inspection and replacement | Filter condition checked and replaced as required, with airflow measured rather than assumed |
| Fan motor and belt inspection | Motor condition, vibration check, belt tension and wear assessment |
| Electrical component testing | Contactors, capacitors, power connections and control wiring inspected, with a thermographic scan of terminations under load |
| Sensor calibration | Temperature and humidity sensor accuracy verified and calibrated, setpoints and deadbands confirmed against how the room actually runs |
| Alarm and control system verification | Alarm functions tested by forcing the condition, BMS and SNMP integration checked, notification routing confirmed to a person who still works there |
| Written service report | Full documentation of findings, measured values trended against previous visits, water circuit status, compliance observations and recommendations |
Commercial
CDW servicing pricing
Australian rates, ex GST, per unit, metro. Multi-unit data halls and multi-site fleets are quoted individually, with the per-unit rate falling as unit count increases. Regional and remote sites attract a mobilisation charge.
Full inspection against the checklist above with a written report. The right starting point where a system has been inherited or its service history is unknown.
Scheduled visits with operational testing, calibration, priority fault response and an annual compliance report. Suits commercial buildings and smaller halls.
Quarterly or custom scheduling, 24/7 emergency response to an agreed SLA, remote monitoring and coordination with your water treatment provider.
Coil cleaning beyond routine, tube cleaning, parts and any cooling tower works are quoted separately. Compare the full range on our maintenance plans page.
Frequency
Recommendedservice schedule
CDW needs a layered approach, because the daily checks are cheap and the quarterly ones need instruments.
| Frequency | Who performs | Key activities |
|---|---|---|
| Monthly or bi-monthly | In-house facility team | Filter inspection, condensate pump checks, alarm verification, general system operation review |
| Quarterly | Professional service | Full checklist, water quality verification, approach temperature, motor and belt inspection, sensor calibration, compliance status check |
| Annually | Professional service | Electrical inspection and thermographic scan, full coil clean, deep diagnostics, risk assessment review, compliance documentation update, cooling tower inspection coordination |
Sites in Queensland, the Northern Territory and northern Western Australia should complete the annual comprehensive service before October, so the system enters summer at full capacity rather than discovering a fouled condenser during the first heatwave.
Where they are
Facilities we service
Coverage
CDW servicingacross Australia
Brisbane and QLD
Brisbane CBD, Tingalpa, Woolloongabba, Eight Mile Plains, Gold Coast, Sunshine Coast, Ipswich, Townsville, Cairns
Our HQ. Humidity raises the latent load and warm ambient raises condenser water temperature, so the annual service is best completed before October.
Sydney and NSW
Sydney CBD, Parramatta, North Ryde, Macquarie Park, Western Sydney, Alexandria, Newcastle, Wollongong
The largest concentration of tower-served data halls in Australia, and a state with registration and independent auditing obligations on cooling towers.
Melbourne and VIC
Melbourne CBD, Port Melbourne, Docklands, Dandenong, Tullamarine, Geelong, Ballarat, regional Victoria
Also a registration and auditing state. Base building coordination is usually required because the tower is rarely under the tenant's control.
Perth and WA
Perth CBD, Fremantle, Kewdale, Kalgoorlie, Pilbara, regional WA
Water restrictions push more sites toward closed glycol loops and dry coolers, which changes both the servicing and the compliance position.
Canberra and ACT
Canberra CBD, Civic, Fyshwick, Mitchell, Barton, Tuggeranong, Belconnen, Queanbeyan
Government data halls, with Supply Nation and ICN Gateway registration for Commonwealth procurement.
SA, NT and Tasmania
Adelaide, Port Adelaide, Edinburgh, Whyalla, Darwin, Palmerston, Katherine, Alice Springs, Hobart
Scheduled visits combined across nearby sites in a single mobilisation to keep travel cost sensible.
Questions
CDW servicingFAQs
What facilities teams ask about condenser water systems. If yours is not here, call 1800 046 344.
What is a CDW CRAC unit?
A CDW, or condenser water, CRAC unit removes heat from a server room or data hall by passing room air across a cooling coil, then transferring that heat into a condenser water loop rather than to an outdoor air-cooled condenser. Like a DX unit it has its own compressor and refrigerant circuit, but the heat rejection happens through a water-cooled condenser. That loop normally runs to a cooling tower, or in a closed system to a dry cooler using a water and glycol mix.
What is included in CDW CRAC servicing?
Condenser water loop inspection with flow and differential pressure measurement, approach temperature trending, evaporator coil cleaning and inspection, water regulating valve and actuator testing, water treatment verification, refrigerant circuit checks under ARCtick licence, filter replacement with airflow measurement, fan motor and belt inspection, electrical testing with a thermographic scan, sensor calibration, alarm and BMS verification, and a written report with measured values trended against previous visits.
How often should a CDW CRAC system be serviced?
Quarterly professional service is the recommendation for CDW, because there are two systems to keep healthy rather than one. In-house monthly or bi-monthly checks cover filters, condensate pumps and alarms. The annual visit adds electrical inspection with a thermographic scan, a full coil clean, deep diagnostics, compliance documentation review and coordination with whoever maintains the cooling tower. Queensland, Northern Territory and northern Western Australian sites should complete the annual service before October.
What are the Legionella compliance requirements for CDW systems in Australia?
The obligations attach to the cooling tower, not to the CRAC unit. AS/NZS 3666 governs air-handling and water systems of buildings for microbial control. In New South Wales and Victoria, cooling tower systems must additionally be registered with the local council, operated under a documented risk management plan, sampled routinely for Legionella, and independently audited annually. Other states impose their own requirements under public health legislation. Requirements are periodically updated, so confirm the current position for your state rather than assuming.
Does a closed glycol loop have the same obligations?
No. A closed loop rejecting heat through an outdoor dry cooler has no evaporative cooling tower, so the registration, sampling and independent auditing obligations that apply to tower systems do not apply. The maintenance focus shifts instead to glycol concentration, corrosion inhibitor levels and dry cooler coil condition. If you are unsure which arrangement your building has, establish it before an audit rather than during one.
What is the difference between CDW and DX CRAC servicing?
A DX unit rejects heat to an outdoor air-cooled condenser, so servicing centres on the refrigerant circuit and condenser coil condition. A CDW unit does everything a DX unit does and adds the entire water side: flow, differential pressure, approach temperature, water regulating valve modulation, water treatment status and condenser fouling. In practice a CDW visit takes longer and produces more numbers, and the compliance context sits alongside it because of the tower.
How can I tell if the condenser is fouling?
Approach temperature is the honest indicator. It is the difference between the condenser water temperature and the refrigerant condensing temperature, and it widens as scale or biofilm builds on the tube surface. Because it moves gradually, a single reading tells you little and a trend across visits tells you a great deal. Rising head pressure, longer run times to hold setpoint and increased energy consumption are the same story arriving later.
Do you service CDW systems outside Brisbane, Sydney and Melbourne?
Yes. Technicians travel from the Brisbane, Sydney and Melbourne hubs, and we cover Perth, Adelaide, Canberra, Darwin, Hobart and regional centres. For regional and remote work we combine scheduled visits across nearby sites into a single mobilisation to keep travel cost sensible, so it is worth telling us about every site at booking rather than only the urgent one.
What CDW brands do you service?
Vertiv Liebert including PDX, PCW and CDW-configured systems, Schneider Electric Uniflair CDW-configured units, STULZ CyberAir in CDW configuration, and legacy Emerson Network Power Liebert PCW and CDW series. We are vendor agnostic and service discontinued platforms as well, confirming parts availability before booking rather than discovering it on site.
Related services
Equipment
CDW platformswe service
Vendor agnostic by design. We service the units you already own, whoever supplied them, and confirm parts availability on discontinued platforms before the visit rather than after.
Not sure whether your loop runs to a cooling tower or a dry cooler, or who is responsible for it? That question comes up on most first visits. Send us the make, model and location of your units and we will establish the arrangement, tell you what the compliance position looks like, and quote the servicing against what is actually there.
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