Cooling Tower and Chiller Plant Labels: Equipment IDs, Pumps, Valves and Basin Heaters
Somebody is standing at the tower with a work order that says "isolate the east cell," and nothing on the equipment says which cell is east.
Important Disclaimer
This article is provided for general informational purposes only and does not constitute legal, safety, or professional compliance advice. Regulations, standards, and codes are subject to change and may be interpreted differently by authorities having jurisdiction (AHJ). Always consult with qualified safety professionals, licensed engineers, or legal counsel to determine the specific requirements applicable to your facility. TagBuilder is not responsible for any actions taken based on this information.
To label a chiller plant, give every device on the chilled water and condenser water loops one unique ID (CH-1, CT-1A, CHWP-1, CWP-1), engrave that ID on a plate fixed to the device, and tag every valve with its service and flow direction (CHWS, CHWR, CWS, CWR). Use screws or rivets at the tower, and use engraved plastic made for outdoor service or engraved stainless. Keep the ID scheme identical across drawings, the BAS and the plates.
What goes wrong when a plant is labeled badly
Most plant mistakes are not dramatic. They are small and expensive in aggregate:
- A technician lock-outs CWP-2 when the work order meant CWP-1
- An operator closes a condenser water isolation valve for a cell that is still in service. Condenser water flow drops, head pressure climbs, and the chiller can trip on high pressure.
- Someone stages the wrong tower cell during a changeover and the plant runs warmer than the setpoint for hours before anyone traces it.
- A replacement plate gets reordered from a photo and arrives in the wrong size because nobody wrote down the original.
None of this takes fancy labeling. It takes one naming scheme applied everywhere.
Map the whole loop before you order anything
Walk the plant in flow order and list every device someone might operate, service or isolate. A chiller plant has two loops, and they should be tagged as two loops.
Chilled water loop
Chillers (evaporator side), primary and secondary chilled water pumps, their VFDs, strainers, balancing valves, isolation valves, bypass and decoupler valves, and the supply and return headers to the building.
Condenser water loop
Chiller condensers, condenser water pumps, cooling towers and individual cells, tower fans and their VFDs, basin heaters, makeup water, bleed/blowdown, the chemical treatment skid, strainers, and isolation valves per cell.
Abbreviations and valve tag colors
The table below lists the abbreviations used in the rest of this article and the tag colors many sites pair with them. There is no single mandatory color code for these services. Follow your site standard, and if there is none, write one down before ordering. The valve tag color codes guide covers the common conventions.
| Abbreviation | Meaning | Commonly seen tag color |
|---|---|---|
| CHWS | Chilled water supply (cold, leaving the chiller) | Green or blue; site-specific |
| CHWR | Chilled water return (warmer, back to the chiller) | Green, sometimes a different shade from supply |
| CWS | Condenser water supply (to the chiller condenser from the tower) | Site-specific |
| CWR | Condenser water return (from the chiller to the tower) | Site-specific |
| MU | Makeup water to the tower basin | Often blue or white |
| BD | Bleed / blowdown | Often yellow or a chemical-service color |
Keep supply and return on the same color family but make the legend itself unmistakable. Color alone does not carry the meaning; the engraved text does.
Equipment ID scheme and plate text
This table gives a suggested ID, example plate text and mounting for each device type. Adjust the numbering to match your drawings.
| Equipment | Suggested ID | Plate text example | Mounting |
|---|---|---|---|
| Chiller | CH-1 | CH-1 / CHILLER 1 / SERVES CHW LOOP | Screws on the control panel door and the frame |
| Cooling tower cell | CT-1A, CT-1B | CT-1A / COOLING TOWER 1 CELL A | Stainless screws or rivets at the walkway side |
| Chilled water pump | CHWP-1, CHWP-2 | CHWP-1 / LEAD / CH-1 | Screws or adhesive on pump base or guard |
| Condenser water pump | CWP-1, CWP-2 | CWP-1 / LAG / CH-1 | Screws on pump base or adjacent frame |
| Tower fan VFD | VFD-CT-1A | VFD-CT-1A / FAN CELL A | Rivets or screws on the drive enclosure |
| Basin heater | BH-1A | BH-1A / BASIN HEATER CELL A / DISCONNECT AT PANEL CP-1 | Screws at the basin and at the disconnect |
| Makeup water valve | MU-1 | MU-1 / TOWER MAKEUP | Tag on a wire loop or screw to the bracket |
| Bleed/blowdown | BD-1 | BD-1 / BLOWDOWN / CT-1 | Screws on the pipe support |
| Chemical treatment | CHEM-1 | CHEM-1 / WATER TREATMENT / CONTACT BEFORE SERVICE | Screws on the skid |
Numbering tower cells
Number the tower, then letter the cells: CT-1A, CT-1B. If the plant has two towers, use CT-1 and CT-2 and letter the cells within each. Say which chiller each cell normally serves on the plate or the schedule, because that relationship is what an operator needs during isolation.
Pump lead/lag
Lead and lag change. Put LEAD or LAG on a separate small plate, not engraved into the main ID, so the ID stays permanent when the rotation changes.
The tower is a hard environment
A cooling tower is wet all the time. Add drift, treatment chemicals and direct sun, and an adhesive-only label on a damp painted surface will not last. Plan for this:
- Fasten mechanically. Use stainless screws or rivets in at least two corners.
- Match the material to the spot. Engraved two-ply plastic made for outdoor use is common on the walkway side. Engraved stainless is the usual choice for tags at the basin and next to the treatment equipment. The indoor vs. outdoor tag materials guide compares the options.
- Size for the walkway. If a person reads it from the walkway, use large text. A 4 x 2 inch plate with 1/4 inch capitals is readable from arm's length; go larger if it is read from farther away.
- Engrave, do not print. Engraved text does not rub off like printed ink.
For cell tags, the 4 x 2 inch cooling tower label, white on blue with mounting holes is a ready starting point. For chiller body plates, the 4 x 2 inch chiller label, white on black with mounting holes fits the same mounting pattern.
Worked example: 2 chillers, 2 tower cells
The following plant has two chillers, one tower with two cells, and lead/lag pumps. Copy it line for line and change the numbers.
Equipment plates
- CH-1 / CHILLER 1
- CH-2 / CHILLER 2
- CT-1A / COOLING TOWER 1 CELL A
- CT-1B / COOLING TOWER 1 CELL B
- CHWP-1 / CHW PUMP 1 / LEAD
- CHWP-2 / CHW PUMP 2 / LAG
- CWP-1 / CW PUMP 1 / LEAD
- CWP-2 / CW PUMP 2 / LAG
- VFD-CHWP-1 / DRIVE FOR CHWP-1
- VFD-CHWP-2 / DRIVE FOR CHWP-2
- VFD-CT-1A / FAN DRIVE CELL A
- VFD-CT-1B / FAN DRIVE CELL B
- BH-1A / BASIN HEATER CELL A
- BH-1B / BASIN HEATER CELL B
Ten valve tags
Each line is the engraved text. The second line gives the service, and the last gives normal position if your site tags it.
- CHWS-1 / CH-1 CHW SUPPLY ISOLATION / NO
- CHWR-1 / CH-1 CHW RETURN ISOLATION / NO
- CHWS-2 / CH-2 CHW SUPPLY ISOLATION / NO
- CHWR-2 / CH-2 CHW RETURN ISOLATION / NO
- CWS-1 / CH-1 CW SUPPLY ISOLATION / NO
- CWR-1 / CH-1 CW RETURN ISOLATION / NO
- CWS-2 / CH-2 CW SUPPLY ISOLATION / NO
- CWR-2 / CH-2 CW RETURN ISOLATION / NO
- CT-1A CELL ISOLATION / CWR TO CELL A / NO
- CT-1B CELL ISOLATION / CWR TO CELL B / NO
For small round tags on pipe-mounted valves, the 1.5 inch CHWS plastic valve tag, white on black and the 2 inch CHWR plastic valve tag, white on green match the chilled water pairs above. At the tower, the 1.5 inch CHWR stainless valve tag is the choice when plastic is not the right fit. See also the CHWS valve tag collection.
Isolation, normal position and keeping the list current
Before any cell isolation, the operator should be able to read the cell ID, the valve ID and the service without looking at a drawing. Labeling the isolation valve for each cell with the cell ID is the single most useful tag on the condenser side.
Normal position (NO/NC) is optional. It helps during shutdowns and startups, but a valve that is moved seasonally can make the tag wrong. If you add it, make it a separate small plate so it can be changed without replacing the ID tag. Keep one master list, mark each tag with the same ID the BAS uses, and update the list when equipment is replaced.
Send one chiller, tower or valve ID and we'll engrave a free sample plate you can test outside at the tower.
Frequently Asked Questions
What does CHWS and CHWR mean?
CHWS is chilled water supply, the cold water leaving the chiller evaporator toward the building. CHWR is chilled water return, the warmer water coming back from the building. Condenser water uses the same pattern: CWS and CWR.
How do you number cooling tower cells?
A common approach is to number the tower and letter the cells, such as CT-1A and CT-1B. If you have more than one tower, use CT-1 and CT-2 with cell letters inside each. Match whatever the drawings and BAS already use.
What labels does a chiller need?
At minimum, an equipment ID plate (CH-1), plates on the control panel and disconnect, and valve tags on the chilled water and condenser water isolation valves with their service. Check the current edition of your electrical code and your AHJ for any required warning or disconnect marking.
What tags hold up at a cooling tower?
Engraved plastic made for outdoor use or engraved stainless, fastened with screws or rivets. Adhesive alone on a wet painted surface tends to let go. Engraved text does not rub off like printed ink.
Should valve tags show normal position (NO/NC)?
Only if your site maintains it. Normal position is useful for startups and shutdowns, but a wrong NO/NC marking is worse than none. If you include it, use a separate small plate that can be updated.
If you are building out the rest of the building, the HVAC equipment abbreviations and tagging scheme carries the same ID logic to air handlers and rooftop units, and the guide to labeling rooftop units covers the equipment above the plant. Our free sample page is the quickest way to test a plate at the tower before you order the full list.
UL, NFPA, NEC, ASME, CEMA, TIA, ANSI and OSHA are names or marks of their respective organizations; TagBuilder is not affiliated with or endorsed by any of them. Requirements above are paraphrased summaries, not the text of any standard. Always work from the current published edition and your AHJ.
