Chiller Breakdown Hire: How to Choose the Right Replacement — Fast

Your chiller has tripped. The building is warming up. The phone won’t stop.

Most facilities managers and engineers in that moment ask the same thing: do I need to hire the exact same chiller to get back online? You don’t. Once you understand why, the whole process gets a lot less stressful.

Below, we cover what type of chiller to hire. Whether you actually need the same capacity as the unit that failed, and what to have ready when you call.

The Quick Answer

Make, model, brand — none of it matters. What does matter:

• Cooling capacity, which may actually be less than your failed unit’s nameplate rating
• Chiller type, matched to what infrastructure you have available right now
• Power, pipework, and access, ready for the hire unit when it arrives

If your cooling tower is out of action or condenser water access is restricted, an air-cooled hire chiller is almost always the faster path. No cooling tower, no condenser water loop — just power, chilled water pipework, and clear airflow.

Do You Need the Same Type of Chiller?

It depends on what’s still operational on your site, not what you had before.

If your failed chiller was air-cooled

Straightforward. Hire an air-cooled unit of equivalent capacity, connect to your existing chilled water pipework, supply 415V 3-phase power, and you’re back online. Minimal setup, no additional infrastructure required.

View our air-cooled chiller hire fleet

If your failed chiller was water-cooled

Here you have a choice, and the right one depends on your site conditions.

Option 1 — Hire a water-cooled chiller. Your cooling tower and condenser water loop stay in use. The hire unit connects into the same pipework. If your tower is functioning, condenser water flow is confirmed, and you need the efficiency of water-cooled operation, this is the right route.

View our water-cooled chiller hire fleet

Option 2 — Hire an air-cooled chiller instead. No cooling tower required. Air-cooled units reject heat directly to atmosphere via the condenser coil and fans, which cuts setup time considerably. Connect to your chilled water supply and return headers, provide power, position with adequate airflow clearance, and you’re running. COP will be lower than water-cooled operation, and rated capacity drops in high ambient temperatures above 40°C. For a short-term emergency hire though, restoring cooling fast is the priority. A marginal efficiency difference over two weeks rarely changes the decision.

If your cooling tower has also failed, or condenser water access is blocked, go air-cooled. It’s the practical call.

What happens when site access throws up constraints?

Sometimes the right chiller type is forced on you by the site itself. When a Brisbane hospital’s heat pump chiller system failed during peak demand, there was no rooftop space available for a temporary unit. Residential properties sat roughly 30 metres away, ruling out standard equipment due to noise output. The solution was a 200kW air-cooled heat pump chiller installed at ground level in the hospital car park. It was connected via 80 metres of Victaulic pipework and flexible hoses to the existing system. The whole thing was commissioned in under 48 hours.

Same principle applied at a Melbourne hotel where the chiller connection point sat on the rooftop of a multi-storey car park with only 2.1 metres of clearance. There was no single unit could fit through. Two smaller chillers, a 60kW and a 65kW air-cooled unit, were mounted in compact frames, transported through the car park, and connected via a 30-metre pipe run to the rooftop system. Total time from initial inquiry to full installation: five hours.

The point is that chiller type and configuration decisions rarely happen in a vacuum. Access, noise, available power, and connection point location all shape the answer.

Do You Need the Same Capacity?

This is where most people get it wrong, and often in both directions.

Your original chiller was probably oversized

Most installed chillers are designed with 20-30% more capacity than actual peak load requires. If your BMS data shows the failed unit was never running at full load, a smaller hire chiller will cover it. The hire unit does not need to match the nameplate of whatever failed — it needs to match your actual load.

Ehen a medical manufacturing facility in New South Wales lost its production chiller without warning, the client initially requested a 10kW unit. That was their best estimate under pressure. After Aircon Rentals inspected the setup and assessed the actual process cooling demand for the sterile surgical kit line, a 21kW air-cooled chiller with a buffer tank and external pump was the correct answer. The unit was tested at the Sydney warehouse that same day with matching hose and cable lengths, delivered and installed the following morning. Production was back running in under 24 hours. Had the client’s initial estimate been accepted without verification, the undersized unit would have failed to maintain the 15-18°C chilled water temperature the process required.

Heat affects rated output — account for it in summer

Air-cooled chillers lose capacity as ambient temperature climbs. A unit rated at 500kW at 35°C ambient may only deliver 420-440kW at 42°C on a hot Australian day. Check the manufacturer’s capacity correction curves if you need precision, or build in a 10-15% buffer above your calculated load as a starting point.

A Victoria winery learned this directly during crush season. An unusually hot summer pushed the grape harvest ahead of schedule, and the existing refrigeration plant couldn’t keep up with peak demand at minus 6°C leaving water temperature. Aircon Rentals deployed a 500kW air-cooled chiller sized to that specific LWT requirement, pre-tested at the Sydney warehouse before dispatch to make on-site commissioning straightforward. The rental also gave the winery a backup should the existing plant fault during the most time-sensitive weeks of their production year.

You may not need to cool the whole building

What actually needs to stay operational right now? In most breakdown situations, you can isolate non-critical zones at the AHU or VAV level and concentrate cooling where it counts — a data hall, a production line, a critical clinical area. Hire for that load. Trying to maintain full building cooling when half the zones are non-critical burns capacity and budget.

A Melbourne dairy manufacturer running yogurt and cheese production through summer. Their production area had no existing air conditioning and insufficient power capacity to support new cooling equipment on their existing supply. Rather than attempting to cool the entire facility, the solution focused specifically on the production space. A 21kW air-cooled chiller paired with a portable fan coil unit and a 28kVA generator to run the system independently of the site’s electrical infrastructure. The fan coil was modified to be mobile, so airflow could be redirected based on where heat load was highest during each shift. Read that full case study here.

Estimating your load

If you have flow and temperature data from your BMS or system gauges:

Cooling load (kW) = Flow rate (L/s) × ΔT (°C) × 4.19

Example: 15 L/s, 6°C ΔT → 15 × 6 × 4.19 = 377 kW

Add a 15-20% buffer and a 450kW unit becomes your starting point.

No flow data? Call anyway. Building size, occupancy type, number of zones served, and AHU configuration is enough for our team to size the right unit quickly.

What If You Need More Than One Unit?

For larger sites, two smaller units running in parallel often beats chasing one large unit.

Two 300kW hire chillers give you 600kW of total cooling capacity, plus redundancy. If one unit faults, the other keeps partial cooling running while you troubleshoot. Smaller units are also easier to position on constrained sites — lighter, lower-profile, and simpler to crane or forklift when access is tight. The Melbourne hotel case above is exactly this: two units where one wouldn’t physically fit, each doing half the load.

For very large plant replacement projects, the equation shifts again. When a regional hospital in Northern NSW needed to replace a 1200kW air-cooled chiller in a detached central cooling plant, a single trailer-mounted 1300kW air-cooled chiller on a purpose-built 40-foot semi-trailer was the answer. The trailer carried the chiller, hoses, electrical cabling, distribution equipment, and a recirculating chilled water pump as a single load. Aircon Rentals’ own prime mover delivered and positioned it without cranes or rigging, which cut installation time and saved the HVAC contractor significant cost on the tie-ins.

View our full chiller hire range

What to Have Ready When You Call

The more detail you can give us upfront, the faster we can get a unit moving.

Cooling capacity

• Nameplate kW or tonnage of the failed chiller
• Or: chilled water flow rate and supply/return temperatures from your BMS or gauges
• Or: building size (m²), occupancy type, and number of zones served

Chiller type

• Was the failed unit air-cooled or water-cooled?
• Is your cooling tower still operational? Is condenser water flow confirmed?

Power supply

• 415V 3-phase available on-site? How many amps?
• Distance from the supply point to where the hire unit will be positioned
• If available power is insufficient, note that — a generator package may be the answer

Pipework

• Chilled water pipe diameter, supply and return
• Connection type — Camlock, Victaulic, or flanged?
• Connection point location — plant room, rooftop, external wall?

Site access

• Truck access to site? Any height, weight, or turning restrictions?
• Crane or forklift available if needed?
• Install location — ground level, rooftop, or basement?

Urgency

• When did the chiller fail?
• Operational impact — occupied building, process cooling, critical environment?

You don’t need every answer before you call. Share what you have and we’ll work through the rest.

How Quickly Can You Get a Hire Chiller On-Site?

In Sydney, Melbourne, Brisbane, and Perth, same-day deployment is possible for genuine emergencies where we have stock. Next-day is standard for most urgent requests.

Regional sites: allow 24-48 hours depending on distance from the nearest depot.

The thing that slows most emergency hires down isn’t equipment availability. It’s incomplete information on the first call. Load requirement, available power, and pipe connection specs let us allocate, load, and dispatch without back-and-forth.

Learn more about our emergency response capability

What Happens When the Unit Arrives?

Our technicians commission the hire chiller on-site. That covers chilled water supply and return pipework connected, electrical connection to your power supply, system flushed and pressure tested, supply water temperature and flow parameters set, and operation confirmed before handover.

Where practical, we pre-test the complete package at our warehouse before dispatch — replicating hose lengths, cable runs, and system pressures so the on-site install is as close to plug-and-play as possible. The medical manufacturing job above is a good example of why that matters: by the time the technician arrived on-site the following morning, there were no surprises.

Commissioning typically takes 2-4 hours from unit arrival, depending on site conditions and connection complexity.

Chiller Breakdown Hire Checklist

When the chiller trips:

• Pull fault codes and alarms from the BMS
• Confirm whether the fault is isolated to the chiller or also affecting pumps, cooling tower, or AHUs
• Identify which zones are down and prioritise by criticality

Before you call:

• Locate the failed chiller’s nameplate — note kW or tonnage
• Check available power at or near the proposed hire unit location
• Confirm site access constraints — gate dimensions, surface load limits, overhead clearance

When you call Aircon Rentals:

• Capacity — nameplate or estimated from flow and delta-T
• Chiller type — air-cooled or water-cooled
• Site address and on-site contact
• Urgency — same-day or next-day

FAQs

Do I need the same brand or model as the chiller that failed?

No. Compatibility comes down to cooling capacity, chilled water pipework size, and available power supply. Hire chillers connect via standard chilled water fittings — the original manufacturer is irrelevant.

What if I don’t know the capacity of my failed chiller?

Call anyway. Building size, usage type, and number of zones served gives us enough to estimate the right hire unit quickly.

Can I hire a smaller chiller than the one that failed?

Yes, in many cases. If the failed unit was oversized for actual load, or you’re running only critical zones during the breakdown period, a smaller unit will handle it. We can work through the load numbers with you.

Do I need to hire pumps as well?

Only if your existing chilled water pumps aren’t providing adequate flow. If primary or secondary circulation is also down, we can supply a chiller and pump package together.

Can I extend the hire if repairs take longer than expected?

Yes. Short-term emergency hire can roll into medium or long-term rental with no penalty. This comes up regularly when replacement parts have long lead times or a new plant is on order.

How long can I hire a chiller for?

Anything from a single day to several months. Extended hire is standard during major plant refurbishments or while waiting on replacement equipment.

Talk to Our Team — 24/7

Our depots in Brisbane, Sydney, Melbourne, and Perth carry air-cooled and water-cooled hire chillers from 20kW up to 1,000kW+, with larger configurations available on request.

Call us when the chiller goes down. We’ll size the right unit, confirm availability, and dispatch. Call 1800 626 996 — available 24/7 for emergency chiller breakdown hire.

Or request a hire quote online.

Planning ahead is easier than managing a crisis. See our Contingency Planning solutions — standby hire agreements that put equipment on hold before you need it.