Planned Chiller Shutdown: How to Keep a Building Cool

Replacing or repairing a chiller means taking the heart of a building's cooling offline, sometimes for days and sometimes for weeks. With the right temporary equipment in place, occupants never notice. Without it, a Texas summer turns a mechanical project into an emergency. Here is how we plan temporary cooling and power for a planned shutdown.

1. Size the temporary cooling to the real load

Start from the building's actual peak cooling load in tons (one ton is 12,000 BTU per hour), not the nameplate of the chiller being replaced. Trend data from the building automation system for the same season is the best source. Then decide how much of that load must be carried:

• Full load for spaces that cannot warm up at all: data rooms, labs, healthcare and secure facilities.
• Partial load where occupied areas can run a few degrees warmer for the duration.
• Spot cooling for isolated critical rooms when the rest of the building can ride it out.

2. Choose the right equipment

• Portable chillers connect to the building's existing chilled-water loop, so the air handlers and terminal units keep working normally. This is the standard choice for a central plant outage.
• Spot coolers and portable AC units serve individual rooms and are quick to deploy, but they need a place to reject heat and a condensate plan.
• Trailer-mounted AC can serve large open areas or temporary structures with ducted air.

3. Plan the power

Temporary chillers draw a lot of power, and the building's chiller circuit may be out of service during the work. Confirm the available electrical capacity early. If it is not enough, size a generator for the chiller's full-load and starting demand plus any pumps, and plan the distribution: cables, panels and connection points, refueling, and where the equipment will sit.

4. Work out the hookups and the site

• Chilled-water connections: check whether the loop has tie-in points, valves and enough pump capacity, or whether temporary pumps and hoses are needed.
• Placement: chillers and generators need level ground, clearance for airflow and service, and a route for hoses and cables that does not block traffic or exits.
• Noise and permits: check local noise limits, fuel storage rules and any permits for temporary equipment before it arrives.

5. Schedule it backwards from the shutdown

Temporary equipment should be delivered, connected and running before the existing chiller goes offline, and stay in place until the new equipment is commissioned and stable. Build in time for testing the changeover in both directions. Rental availability tightens in summer, so reserve equipment early for work between May and September.

Why one team for the project and the rentals

When the same contractor runs the mechanical work and the temporary cooling and power, there is no hand-off between companies during the most fragile part of the job. The crew that disconnects the old chiller is the crew that knows exactly what the temporary setup is carrying.

Frequently asked questions

How do you size temporary cooling for a chiller shutdown?

Start from the building's actual peak cooling load in tons (one ton is 12,000 BTU per hour), ideally from building automation trend data for the same season, not from the nameplate of the chiller being replaced. Then decide which spaces need full load, partial load or spot cooling.

What is the difference between a portable chiller and a spot cooler?

A portable chiller connects to the building's existing chilled-water loop, so air handlers and terminal units keep working normally. Spot coolers serve individual rooms and deploy quickly, but they need a place to reject heat and a condensate plan.

Do temporary chillers need a generator?

Often. Temporary chillers draw a lot of power, and the building's chiller circuit may be out of service during the work. If the available electrical capacity is not enough, size a generator for the chiller's full-load and starting demand plus any pumps.

How early should temporary cooling be reserved in Texas?

Early, especially for work between May and September, when rental availability tightens. The equipment should be running before the existing chiller goes offline and stay until the new equipment is commissioned and stable.

About Zebrix Group

Zebrix Group is a service-disabled veteran-owned, TDLR-licensed HVAC and mechanical contractor based in The Woodlands, Texas. We plan and run chiller replacements and provide generator, spot cooler, portable chiller and portable HVAC rentals for shutdowns, emergencies and peak demand across Texas. See how we plan temporary cooling for planned chiller shutdowns, our portable chiller rentals in Houston, or contact us about an upcoming shutdown.

About the author: Zachary (Zack) Butler is the founder and CEO of Zebrix Group Inc. and a U.S. Navy veteran. He builds Pulsix AI, one system for a building owner's buildings, work, money and risk.

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