BAC's Series 3000 O&M manual says to install basin heaters on applications without a remote sump, to heat trace and insulate exposed piping, and to manage icing with a temperature setting (a recommended minimum process fluid temperature of 43°F) and fan control, including fan cycling at no more than six on-off cycles per hour. Check these against your unit's manual.
What the manual says about winter operation
The Cold Weather Operation section of the BAC Series 3000 Operation & Maintenance manual (3000_om_20200806) covers winter operation. As we read it, it says three things:
- Install basin heaters on applications that do not have a remote sump.
- Heat trace and insulate exposed piping.
- Control icing with a temperature setting and fan control. The manual recommends a minimum process fluid temperature of 43°F (6.1°C), and its fan control options include fan cycling, with no more than six on-off cycles per hour, and speed reduction.
A remote sump holds the system water in a separate location instead of in the tower basin. The manual ties the heater guidance to applications that do not have one.
Basin heater temperature and icing control are different jobs
The figures in the manual describe different things. The 43°F figure is the manual's recommended minimum process fluid temperature, part of its temperature setting for icing control. The six on-off cycles per hour figure is a limit on fan cycling when you control icing by cycling the fan. Neither one is a basin heater setpoint.
For the heater itself, BAC's FXV handbook (p.C56) describes factory-installed basin heaters with a thermostat that maintain a water temperature of 40°F (4.4°C). That handbook is for the FXV closed circuit cooler, a different product line, and it is a product description, not a Series 3000 instruction. We cite it only to show how BAC describes the heater's purpose. Use the setpoint and the heater data in your own unit's documents.
How the icing controls differ
The temperature setting works on the water side: the manual recommends keeping the leaving water temperature as high as possible, with a recommended minimum process fluid temperature of 43°F. Fan cycling turns the fan on and off, and the manual caps the rate at six on-off cycles per hour. Speed reduction lowers the fan speed instead of stopping it. The manual covers these in the same winter operation section as heaters and heat trace. Which one your unit can use depends on its controls and drive, so settle that with your controls contractor and your unit's manual.
Test the heater circuit before the cold weather
A heater circuit that has sat unused since spring can fail on the first cold night. Before freezing weather, check that the thermostat is set, the sensing bulb is in its well, any low-water switch makes with the basin at level, and the heat trace and insulation on exposed piping are intact. Record the date and what you found. If a part needs replacing, identify it from the serial number while there is still time to quote it.
What is in a basin heater circuit
The O&M pages we reviewed do not list heater failure modes, so this section describes the circuit and not a diagnosis. Depending on the model and the factory options, a BAC basin heater circuit can include:
- The immersion heater itself.
- A thermostat, with a sensing bulb that sits in a well in the basin.
- Low-water protection, such as a float switch, so the heater is not energized without water over it.
Which of these your unit has comes from its wiring diagram, not from this article.
How to check a basin heater that is not heating
- Lock out and tag out. Basin heaters run on line voltage. De-energize the heater circuit and verify it is dead before any work.
- Pull up the wiring diagram. Confirm which devices are in your heater circuit before you start testing.
- Check the thermostat. Confirm the setpoint and that the sensing bulb is seated in its well.
- Check low-water protection. If your circuit has a float switch, confirm the basin water level is high enough for the switch to make.
- Check the supply. With the circuit energized by a qualified person, confirm the voltage at the heater matches the heater's nameplate data.
- Check the heater element and wiring. Look for damage, corrosion and loose connections, and check continuity.
- Check the heat trace and insulation. The manual calls for both on exposed piping.
- Review the icing controls. If ice forms despite a working heater, review the temperature setting and the fan control methods the manual lists.
What to know before you order a heater or control
Our heater listings carry the kW rating, the voltage and phase, and the pipe thread in the title. Those details come from the listing and are a starting point only. Sizing a heater for a tower is outside this article. Use the data from your unit's documents, and send us the serial number so the part can be confirmed.
The product page for 313859 — BAC Thermostat (A19, N4X) lists 310382 under Replaces. If your old thermostat carries 310382, that listing is the one to look at. We also list a well for the A19ANC-1 bulb, and an electric float switch (F-63). Whether your heater circuit uses any of them depends on the model and the factory options.
BAC heater and control parts we list
| Component | Role in this issue | Where to find it |
|---|---|---|
| Basin heater, 2 KW | Immersion heater; quote-only; kW, voltage and thread in the title | 02KW43 — BAC 2 KW 480/3/60 Heater 2" MPT |
| Basin heater, 5 KW | Immersion heater; quote-only; kW, voltage and thread in the title | 05KW23 — BAC 5KW 208/3/60 Heater 2" MPT |
| Thermostat | Thermostat; the product page lists 310382 under Replaces | 313859 — BAC Thermostat (A19, N4X) |
| Thermostat bulb well | Well for an A19ANC-1 bulb, per the title; quote-only | 310383 — BAC Well For A19ANC-1 Bulb |
| Float switch | Water-level switch; use only if your circuit includes one | 310620 — BAC Electric Float Switch (F-63) |
BAC heaters in other kW and voltage ratings are in the Parts Available by Quote collection. Use the request a quote page with your serial number.
Scope: The winter operation points come from the Cold Weather Operation section of BAC's Series 3000 O&M manual, and the 40°F heater description from the BAC FXV handbook, p.C56. Other BAC lines need their own O&M manual. Confirm the exact wording at those pages for your edition. Heater, thermostat and switch listings are described only as their titles state.
Before you order
Confirm your unit's exact model and serial number from its nameplate before ordering. Search the part number in our site search, browse the Baltimore Aircoil (BAC) parts collection, and read our BAC parts guide. To confirm fit, contact us at help@totalhvacparts.com with your model and serial number.
Frequently Asked Questions
Do I need a basin heater on a cooling tower?
On a BAC Series 3000, the manual says to install basin heaters on applications without a remote sump. If your system has a remote sump, check your unit's manual for what it requires.
How do you protect a cooling tower from freezing?
The Series 3000 manual says to heat trace and insulate exposed piping, install basin heaters where there is no remote sump, and control icing with a temperature setting and fan control, such as fan cycling or speed reduction.
What does a cooling tower basin heater thermostat do?
It switches the heater based on the temperature its sensing bulb sees in the basin. We list BAC thermostats, and the 313859 page lists 310382 under Replaces. Confirm the thermostat for your unit by serial number.
How often can I cycle the fan to control icing?
The Series 3000 manual lists fan cycling as one fan control method, with a maximum of six on-off cycles per hour. It also recommends a minimum process fluid temperature of 43°F and covers speed reduction as another fan control option.
Sources
- BAC Series 3000 Operation & Maintenance Manual, 3000_om_20200806, Cold Weather Operation section
- BAC FXV Handbook, fxv3_handbook, p.C56
Basin heaters operate at line voltage and cooling towers have rotating fan equipment, open water basins and, in cold weather, ice. Service should be performed only by qualified personnel, following BAC's operation and maintenance manual for your unit and your facility's lockout/tagout procedures.