Factory-Assembled vs Field-Erected Cooling Towers: Which Fits Your Project?
A cooling tower can reach your site in one of two ways. It can be built in a factory and delivered ready to set, or it can be built on your site from a pile of parts by a specialty crew. That choice drives your installation schedule, your labor bill, how much construction your facility has to live with, and how confident you can be in the finished product.
Cooling Tower Systems (CTS) builds factory-assembled fiberglass (FRP) towers in Macon, Georgia. This page explains how the two approaches differ, where each one makes sense, and what to expect when a CTS tower arrives on your site.
The short answer
For almost every commercial, HVAC, and light-to-heavy industrial load, a factory-assembled tower is faster to install, cheaper to put in, and more predictable. Field-erected towers are built for very large loads, typically power generation, refining, and large chemical plants, where a single tower must reject far more heat than any packaged unit can handle.
The CTS Model T-2 line covers 45,000 BTU/hr (T-23) up to 22,500,000 BTU/hr (T-3500) in a single factory-built tower. Larger loads can be met with multiple towers working in parallel, which also gives you redundancy that a single field-erected tower does not.
What is a factory-assembled cooling tower?
A factory-assembled (also called packaged or modular) cooling tower is designed, built, and checked in the manufacturer's plant. It ships to your site either completely assembled or in a small number of large, pre-built sections. The installing contractor sets it on a prepared pad or steel support, connects the piping and power, and starts it up.
At CTS, the following applies:
- Models T-23 through T-280 (up to 80 nominal tons) ship completely assembled from Macon, Georgia, by LTL freight. The tower comes off the truck in one piece, ready to set.
- Models T-2100 through T-3500 are built and pre-fitted at the factory, then shipped in major sections that a small crew bolts together on site. The casing, basin, fill, and drive components are all made and checked before they leave the plant.
- Every CTS tower is designed, engineered, and tested by our own factory. CTS has been a member of the Cooling Technology Institute (CTI) since 1972.
What is a field-erected cooling tower?
A field-erected tower is built on site, much like a small building. Raw materials such as structural framing, a concrete cold-water basin, fill, drift eliminators, distribution piping, fan decks, and fan stacks are delivered separately. A specialized crew then assembles the structure in place.
Field-erected towers exist because some loads are simply too big to ship. A large power plant may need a cooling tower the size of an office block. For those projects, building on site is the only option. For smaller loads, it adds time, cost, and risk without a matching benefit.
Side-by-side comparison
| Factor | Factory-assembled (CTS Model T-2) | Field-erected |
|---|---|---|
| Where it is built | In the factory, under controlled conditions | On your site, outdoors, exposed to weather |
| On-site labor | 1 to 6 workers, from about 1 man-hour (T-23) to 270 man-hours (T-3500) | Specialty erection crew, often for weeks or months |
| Time from delivery to operation | Hours to a few days | Weeks to months of construction before start-up |
| Foundation | Level pad or steel support frame | Usually a poured concrete basin, engineered for the structure |
| Quality control | Factory jigs, repeatable processes, inspection before shipping | Depends on the crew, the weather, and site conditions |
| Cost certainty | Fixed equipment price; small, predictable install scope | Larger exposure to labor overruns, delays, and change orders |
| Disruption to your facility | A crane lift and a short install window | An active construction zone for an extended period |
| Capacity per tower | Up to 22,500,000 BTU/hr per T-3500; add towers for more | Very large single-tower capacity |
| Relocation | Can be rigged, lifted, and moved | Effectively permanent |
| Warranty (CTS) | 20 years on FRP casing and basin, 2 years on PVC fill, 1 year on fan motors and drive components | Varies by builder and contract |
Advantage 1: Less on-site labor
On-site labor is often the most unpredictable line in a cooling tower project. Field crews are paid by the hour, and their hours expand with weather, site access, and coordination with other trades.
A factory-assembled tower moves most of that work into the factory. Here is the labor CTS publishes for assembling each size of Model T-2 tower on site:
| Models | Workers | Hours per worker | Total man-hours |
|---|---|---|---|
| T-23 to T-215 | 1 | 1 | 1 |
| T-220 to T-230 | 1 | 1.5 | 1.5 |
| T-240 to T-260 | 2 | 2 | 4 |
| T-270 to T-280 | 2 | 4 | 8 |
| T-2100 to T-2125 | 3 | 5 | 15 |
| T-2150 to T-2175 | 3 | 7 | 21 |
| T-2200 to T-2250 | 4 | 8 | 32 |
| T-2300 to T-2350 | 4 | 12 | 48 |
| T-2400 to T-2500 | 5 | 18 | 90 |
| T-2600 to T-2700 | 5 | 24 | 120 |
| T-2800 to T-3000 | 5 | 40 | 200 |
| T-3250 to T-3500 | 6 | 45 | 270 |
Source: CTS Assembly Man Hours (PDF).
For example, a 250-ton Model T-2250 needs four workers for one 8-hour day. A field-erected tower of similar duty would typically need an erection crew on site for weeks. Fewer hours also means fewer people working at height, which lowers your safety exposure.
Advantage 2: Faster startup
Speed matters most when a tower has failed, when a production line is waiting, or when a building cannot open until cooling is online.
- Short lead times. Assembled models T-23 through T-280 ship by LTL freight, typically within 1–2 business days after the order is received and accepted, when in stock. Larger models generally need 2–4 weeks to build and prepare for shipping.
- Short install window. Once the tower is set, the remaining work is piping, electrical hookup (the connections are in the junction box on the fan motor), filling the basin, and start-up.
- Less site preparation. A level pad or steel frame replaces the engineered concrete basin that most field-erected towers need.
Industry examples point the same way. In one published replacement project, a plant installed an array of factory-built modules in four days, compared with an estimated 60+ days for a field-erected tower of the same size (ACHR News).
Advantage 3: Factory quality control
A tower built in the field is only as good as the conditions on the day it was built. Rain, cold, dust, untrained help, and schedule pressure all show up in the finished structure. A factory removes most of those variables.
- Controlled lamination. CTS casings and basins are fiberglass-reinforced polyester laminated with unsaturated polyester resin and finished with a UV-protective gel coat. Laminating indoors keeps resin cure, glass content, and thickness consistent.
- Repeatable parts. Basins, casings, fill, louvers, and spray assemblies are produced to the same drawings every time, so replacement parts fit years later.
- Tested design. CTS states that its towers meet and exceed CTI STD 201 for all models. Thermal performance is designed in, not improvised on site.
- Backed by a long warranty. Factory construction is what allows CTS to offer 20 years on the FRP casing and cold-water basin.
Corrosion is where field-built steel and wood towers often fail first. CTS towers use FRP for the casing and basin, which does not rust. See our FRP vs galvanized steel comparison for details.
When a field-erected tower still makes sense
To be fair to the other side, field erection is the right call when:
- The heat load is far beyond what several packaged towers can handle, as in utility power plants or large refineries.
- The site requires a specific structure, such as a large concrete basin shared by many cells.
- The owner plans to run the tower for many decades and wants a structure maintained like a building.
If your load is under roughly 1,500 nominal tons per tower, or you can split it across several towers, a factory-assembled tower is usually the better buy. If you are not sure, send us your numbers and we will tell you.
What to expect when your CTS tower arrives
We publish everything you need to plan the install before the truck arrives:
- Rigging and lifting. Read the rigging, slinging, and lifting guide before delivery. Models T-23 to T-260 have a one-piece round FRP basin and are lifted with straps around all four feet. Models T-270 to T-2175 use four straps spaced 90 degrees apart, kept off the bolted seams. Models T-2200 to T-3500 lift from straps under the truss pipes and ring #1. Every lift uses a guide and safety line on the fan motor eye bolt. Make sure your crane or boom truck can handle the tower's complete dry weight. The rigging instructions (PDF) and rigging diagram for T-23 to T-2175 (PDF) have the details.
- Assembly (larger models). Follow the assembly instructions and the assembly drawings for models T-23 to T-3000. You can also watch the cooling tower assembly video.
- Piping. Plan inlet, outlet, and any bypass lines with our piping and plumbing guide for bypass lines.
- Start-up and service. Keep the operating instructions and service manual (PDF) with the tower.
How installation affects total cost
The purchase price is only part of what a tower costs. Freight, rigging, assembly, piping, electrical, water treatment, energy, and maintenance all add up over the tower's life. Factory assembly cuts the install lines, and FRP construction cuts the maintenance lines. See the full breakdown in our 20-year total cost of ownership guide for FRP cooling towers.
Related reading: counterflow vs crossflow cooling towers, cooling tower replacement and retrofit guide, and the full Model T-2 line.
Frequently asked questions
Do CTS cooling towers ship fully assembled?
Models T-23 through T-280 (up to 80 nominal tons) ship completely assembled from Macon, Georgia. Larger models, T-2100 through T-3500, ship in factory-built sections and are bolted together on site by a small crew.
How long does it take to install a factory-assembled cooling tower?
Setting an assembled tower takes a crane lift and a few hours. For sectional models, assembly ranges from 15 man-hours (T-2100) to 270 man-hours (T-3500). Piping, electrical, and start-up follow.
Is a field-erected cooling tower more durable?
Not necessarily. Durability depends mostly on materials and maintenance. CTS FRP towers carry a 20-year warranty on the casing and cold-water basin because FRP does not rust.
What is the largest single factory-assembled tower CTS makes?
The Model T-3500, rated at 22,500,000 BTU/hr. Larger loads are handled by installing multiple towers in parallel.
Do I need a concrete basin?
No. CTS towers include their own FRP cold-water basin. They need a level, properly designed pad or steel support.
Get a factory-assembled tower sized for your load
Send us your flow rate or heat load, entering and leaving water temperatures, and location. We will recommend a model and tell you how it will ship and install.