From a data centre cooling cutover to a standby hospital chiller system, two technically complex projects show how Coates engineered temporary HVAC solutions around real-world constraints including pressure, power, footprint and operational risk.
Temporary HVAC projects are often described by the equipment supplied – chillers, pumps, hoses, generators and switchboards. But according to Kurt Edwards, Group Manager for Power & HVAC at Coates, the real engineering challenge lies in configuring temporary systems within the constraints of the existing site.
Two recent projects highlight that challenge in practice: one supporting condenser water pipework upgrades at a data centre, and the other delivering standby cooling redundancy for a major hospital after the failure of two permanent chillers affected their capacity in reserve.
“In fixed plant, you design to heat loads and the process is more exact,” Edwards said. “In temporary plant, you’re designing around equipment, footprint, available power, fluid operating pressures, chiller hose limitations, pressure drops and how the building is likely to behave once connected. That’s where the real engineering work is.”
Project one: Temporary cooling for a data centre cutover
Coates was engaged by a specialist mechanical contractor to maintain cooling while condenser water pipework upgrades disrupted the normal cooling tower arrangement serving a data centre.
Under normal operation, cooling towers circulated water between the roof and the computer room air-conditioning systems, removing heat from the data floor and rejecting it externally.
Once those connections were affected by the planned works, an alternative temporary cooling arrangement was required at ground level to keep the system operating during the cutover.
Coates configured a temporary plant comprising:
- 3 x 200kW chillers manifolded together
- Skid-mounted pumps operating in series
- An open buffer tank for purging air during setup
- An expansion tank for in-service thermal expansion control
- A 500kVA generator
- A 10,000-litre fuel cell with fuel service support
- 2 x 400A switchboards
The system was designed to deliver 600kW of temporary cooling while accommodating regularly changing connection points inside the building. Due to the limited footprint, Coates used three slimline chillers in place of a single larger unit, increasing the complexity of the hose arrangement and necessitating the installation of manifolds.
“The chillers couldn’t be moved once positioned, but the connection points into the building changed as the works progressed,” Edwards said. “We designed a valving and hose arrangement so those changes could happen without introducing air into the building systems and without requiring onsite supervision.”
An open buffer tank was used to refill and purge the system each time the connection points moved, then the pumps were run and water cycled through the temporary pipework to enable air to escape through the open tank. Once purged, the buffer tank was isolated, the expansion tank brought online and the temporary system opened to the building.
“Normally the cooling tower basin provides room for fluid to expand,” Edwards said. “With the towers taken offline, we had to replicate that function at ground level. The tank had to be switched in and out to allow for reconnection, priming and air purging through a series of valves operated by site mechanical plumbers."
Project two: Standby redundancy for a major hospital
A major hospital required a fully commissioned standby chiller system after the simultaneous failure of two permanent chillers. While cooling capacity remained available, the loss of redundancy meant a temporary system was needed that could be cut over by onsite staff if required.
Here, the key constraints were power, footprint and potential noise.
“Power was the defining constraint,” Edwards said. “Diesel generation would have increased footprint, noise and operating costs, so we connected through the site's main switch room. Available circuit breakers ultimately dictated the equipment selection, resulting in the selection of three 400kW chillers.”
Coates engineered and installed a standby cooling system comprising:
- 3 x 400kW chillers
- Parallel electric pumps for redundancy
- Custom chilled-water manifolds
- An open buffer tank for priming
- Temporary supply and return hose-work
- Scaffold and cable tray infrastructure
- Electrical integration with the existing switchboard
The next challenge was the building’s operating pressure. Coates designed the temporary plant to draw warm water from the chilled water return header and reintroduce it on the low-pressure side of the hospital’s chilled water supply pumps.
This allowed the temporary system to operate within the pressure limits of the temporary hosework while still using the building's primary pumps to achieve the required hydraulic performance.
“The building hydraulics created a significant challenge,” Edwards said. “Working pressures were close to the limits of temporary hose work, which is common in multi-storey facilities. We had to carefully design the connection points and flow paths so the system could operate safely while still achieving the required performance.”
The installation involved extensive temporary infrastructure, including modifications to plant pipework, scaffolding to support chiller hoses and cables as they rose six meters from the basement level forming a temporary riser, security fencing and traffic management measures to maintain safe public access and support ongoing hospital operations.
To power the temporary chiller plant, Coates installed more than two kilometres of 240mm² cable, including three-phase and parallel cable runs, along with extensive temporary hose infrastructure.
Because the standby system was tied into critical infrastructure, commissioning was approached with caution.
“The electrical supply was designated from three individual switchboards, so testing and energisation were carefully planned. We worked closely with the electrical contractor and site management to minimise any risk of disruption,” Edwards said.
What these projects reveal about temporary HVAC design
For Edwards, both projects reinforce the same principle: successful temporary HVAC projects are shaped by site constraints, not equipment selection.
“You’re usually working to a limiting factor like footprint, power, pressure or access. Or you’re dealing with oversized plant and then managing turndown and control so you don’t short-cycle equipment. It’s never just a case of dropping in a chiller and walking away,” he said.
That practical engineering mindset is what enables temporary cooling systems to support critical works and operational continuity in complex environments.
“Every site is different,” Edwards said. “The solution only works if you can adapt the plant, the hydraulics and the operating procedures to the reality of the job.”