Chiller-plant controls and integration

• Chiller staging Chillers start and stop on measured cooling load, with run hours shared across the machines.
• Chilled-water reset Supply temperature is raised when the load allows, so the chillers do less work.
• Variable flow Variable-speed pumps run to what the system needs, including variable primary flow plants.
• Condenser water and towers Tower fans and condenser pumps are controlled for the best combined efficiency, not just the coldest water.
• Metering and efficiency Power, flow and temperatures are metered so that plant kW/RT is calculated continuously and can be checked.

Chiller makers often describe their controllers as “BACnet-ready”. On site, the BACnet interface may still need an option card, a gateway or a licence before it shows the points you need, and some values update too slowly to control from. We treat a new chiller as untested until it has passed these steps:

1. Agree the points list

   The objects WebCTRL will read and write are agreed with the chiller supplier before delivery, using the maker’s protocol documentation (PICS).

2. Set up the network

   Device instance, IP address, port and, where the chiller sits on another subnet, BBMD settings are fixed and recorded.

3. Test every read

   Each value is compared with the chiller’s own display, checking units, scaling and how often it updates.

4. Test every write

   Setpoints and start and stop commands are tested at the agreed BACnet priority, including what the chiller does when WebCTRL releases control.

5. Trend a full cycle

   Key values are trended through start-up, load changes and shutdown to catch values that freeze or go missing.

6. Sign the points list

   The tested list is signed by the chiller supplier and Goldmarktech, and handed to the owner with the graphics.

Read our article on what “BACnet-ready” should mean at handover

A tested points list

Every object, its test result and the date of the test.

Plant graphics

Live values, alarms and setpoints on WebCTRL screens.

Trends and alarms

Set up and explained to your operators.

The sequence of operation

The written logic the plant follows, updated to as-built.