Planning a chiller replacement in an occupied building

Replacing chiller plant in a building that is still being used is a logistics problem with a mechanical component, rather than the other way round. Most of what goes wrong is decided before anyone touches the machine.

Access, first and in detail

How does the old machine leave and the new one arrive? Route, crane position, road closures, out-of-hours permissions, floor loading on the route, and whether doors and risers are wide enough. On a rooftop plant this is frequently the single longest lead item, and it is worth surveying before the equipment is selected rather than after.

Cooling during the changeover

Decide early whether the building can tolerate the outage. Options are usually staged replacement where there is more than one machine, temporary plant hired in, or working through a low-demand period. Each has a cost; discovering the need for the second one mid-project has a larger one.

What the new machine expects

A replacement rarely matches the original footprint, weight, electrical load, connection positions or clearances. Check the structural capacity of the plinth, the electrical supply, and the water connections against the new machine, not the old one. Refrigerant choices have moved on, which sometimes changes what is possible in the same space.

The system it connects to

A new chiller on old pipework inherits everything wrong with that pipework. Water quality, strainer condition, valve function, insulation condition and pump performance are all worth assessing while the system is open. The marginal cost then is small; afterwards it means draining the system again.

Sequence

Agree the order of works, the isolations required, who approves each one, and what the fallback is at each stage. Write it down. On an occupied building the plan is what lets you stop safely if something is not as expected.