Cooling tower operation is often required in freezing weather for either comfort air conditioning in the central core of a large building, or for industrial processes. To protect the cooling tower from freezing during shutdown periods, Cooling Tower Systems has developed a full line of winterizing heaters. Those shown in this section are used when heat distribution is required over a long length, or when an over-the-side construction is required, as in ceramic, concrete or fiberglass basin. 2" pipe thread heaters, with copper tubular elements are commonly used in the sump when full-length distribution is required. Alternately, to protect both the tower and its piping, the water may be pumped through an Instantaneous Heater.
Construction
Two Constructions are available:
Pipe Thread Heaters are furnished with a Scru-Tite hub, which has a built-n O-ring and locknut to make a pressure-tight joint through a hole in metal basin walls. The heater is screwed into this hub in the field.
Over-the-Side Heaters eliminate the necessity for cutting a hole in a metal basin and are desirable for installations in non-metal basins. Internal wiring runs from the horizontal heater elements through a vertical riser and extension arm with an outlet box located over the side of the basin.
Adjustable Sludge Legs are furnished on all heaters. They are located on five foot centers to keep the element in place even in high water velocities. The legs are adjustable for heights between 2" and 3-1/2"; longer legs are available on special order.
Elements - Both constructions utilize an 80/20 nickel/chromium resistance coil strung through cylindrical ceramic cores. This assembly is slipped into a Type 304 Stainless Steel sheath. All voids are filled with magnesium oxide.
Elements are available in two sizes: Series 761 heaters have 3/4" diameter elements for single phase operation up through 480 volts, and are most commonly used. Series 762 heaters have 1 1/4" diameter elements for both single and three phase operation, up through 480 volts, and in higher KW ratings (up to 20 KW). Consult our office for specific wattage limitations at various voltages.
Element lengths up to 240" are listed in the accompanying table and are available from stocked tubing. Lengths up to 360" are available on special order.
Liquidproof/Explosion-Resistant Outlet Boxes are furnished on all heaters.
Controls
Thermostats and low water cutoffs are stocked and available as individual components or mounted and pre-wired into NEMA 4 control Panel-boards. Accessories for controls are designed for mounting through a basin wall. Consult factory for pricing.
Thermostats, required to energize the heater as the water temperature reaches the freezing point, are bulb and capillary devices with a 35° to 110° F range and a fixed 3° F differential. Each thermostat is furnished with a stainless steel well to house and permanently locate the bulb. The well is installed through a Scru-Tite hub, also furnished, which should be at the same level as the heater.
The thermostat is normally housed in a NEMA 4 weatherproof enclosure, which can be located up to 3 feet away from the well. For indoor or protected installations, the thermostat is available in a NEMA 1 sheet metal enclosure.
In most instances, the heater load can be carried directly by the thermostat, which has the following non-inductive single phase ratings:
- 3000 Watts at 120 Volts
- 4575 Watts at 208 Volts
- 5280 Watts at 240 Volts
- 4985 Watts at 277 Volts
Three phase heaters, 480 volt heaters, and those with ratings exceeding the above require a magnetic contactor. See Bulletin C81-2.
Low Water Cutoff - If the heater is operated when it is not completely covered with water, irreparable damage may result. The low water cutoff prevents such damage. It consists of two components: A Type 316 Stainless Steel probe, installed at least 2" above the element heating; and a relay to deenergize the heater when the water level drops below the probe. A weatherproof cord connects the probe and relay. The relay is capable of carrying heater loads up to 20 amps at 110 volts and 16 amps at 220 volts, single phase. Above this capacity, a magnetic contactor is required.
NEMA 4x Panel Board - Dimensions 6" x 12" x 10". Designed for cooling tower applications. Built in: 0 to 100°F thermostat calibrated for freeze protection. Low water cutoff - floatless type with low voltage probe. 3 pole contactor rated 40 amps. Accessories for mounting sensors through basin with 2" NPT pip plug specify power voltage 120, 280, 240 or 480. Stock item available for quick delivery.
UL Listing - Both Pipe Thread and Over-the-Side constructions are listed by the Underwriters' Laboratories under Reference E23541 in lengths through 240" and ratings through 40 amps (24 amps at 480 volts, 3 phase). This broad UL listing insures both the purchaser and electrical inspector of safe operation with a wide variety of operating characteristics.
How To Order Specify:
1. Catalog Series
Series 761 for 3/4" diameter. (Single phase only)
Series 762 for 11/4" diameter. (Single or three phase)
2. Element Length
See listings. Consult factory for lengths over 240".
3. Type of Construction
Pipe Thread or Over-the- Side.
For over-the-side construction, specify riser height (C-Dimension).
4. Sludge Leg Height
If legs must be higher than 3 1/2".
5. Voltage
120, 208, 240, 277 and 480 volts are standard. Specify "Special Voltage" if required (no extra charge).
6. KW Rating
Consult your local representative for advice on KW rating required to prevent freeze up. Most KW ratings available in length and diameter required.
7. Thermostat
Catalog No. 230-12WCL for NEMA 4 enclosure; Catalog No. 230-12WC for NEMA 1 enclosure. Well and Scru-Tite hub automatically furnished.
8. Low Water Cutoff
Catalog No. B-1480 includes relay in NEMA 4 enclosure, Probe, Scru-Tite hub, bushing, cord and connector. Control voltage will be the same as heater voltage except in the following cases where you must specify control voltage. If heater:
(1) draws more than 20 amps at 110 volts or 16 amps at 220 volts, or
(2) is three phase.
9. Flange for Mounting Low Water Cutoff and Thermostat Well Through Wooden Tower
Standard CTS cooling tower heaters are built with Scru-Tite hubs for mounting through a metal basin. If it is necessary to mount the heater through a basin wall that is other than metal, e.g., wood, heaters can be furnished with flanges for low water cutoff and thermostat well.
