The BAC Series 3000 O&M manual says to inspect the make-up valve assembly monthly and adjust it if necessary, and to inspect the valve annually for leakage, replacing the valve seat if necessary. If the basin overflows, check make-up water pressure (the manual gives 15 to 50 psig), float position and valve leakage first.
What the manual says about the make-up valve
On page 26 of the Series 3000 Operation & Maintenance manual (3000_om_20200806), BAC gives three instructions for the make-up valve. Inspect the assembly monthly and adjust if necessary. Inspect the valve annually for leakage, and replace the valve seat if necessary. Maintain make-up water pressure between 15 and 50 psig.
The same page covers three checks that bear on an overflow: water pressure, float position and leakage. The manual does not include a troubleshooting table for an overflowing basin, so this article stays with those checks. It does not name a single cause, and it does not treat replacing the whole valve as the first answer.
These checks are for a mechanical make-up valve operated by a float. If your unit uses an electric water level control instead, use the manual section for that control.
Basin overflowing: what to check
- Note the conditions. Record whether the basin overflows with the pump running, stopped or both, and whether make-up water keeps flowing while the level is high.
- Check make-up water pressure. Compare the supply pressure at the valve with the 15 to 50 psig range in the manual (p.26). Pressure outside that range is a finding on its own.
- Check float position. Confirm the float ball rides at the level the valve is set for, and adjust if necessary (p.26).
- Check for leakage. With the basin at its normal level, see whether water still passes the valve. The manual calls for an annual leakage inspection and says to replace the valve seat if necessary.
- Inspect the float ball. Look for cracks, damage, or a ball that no longer rides freely on its arm.
- Inspect the arm and linkage. Look for binding, bending or wear that keeps the valve from closing fully.
- Match the part to the finding. A worn seat, a damaged ball and a damaged valve body are three different parts. Replace what the inspection points to.
Where the make-up valve fits in basin level control
A cooling tower loses water continuously to evaporation and bleed. The make-up valve replaces it, and the float tells the valve when to open and close. Because the valve works every hour the tower runs, it is one of the few components with a monthly line in the maintenance schedule. A valve that closes late fills the basin past its normal level. A valve that does not open fully lets the level fall.
That is why the manual pairs the monthly inspection with an adjustment step: a float that sits in the wrong position is a setting to correct before it is a part to replace.
What a monthly make-up valve inspection looks like
Walk the basin level through its range if the unit allows it. Watch the valve open as the level drops and close as it recovers. Look at the float ball, the arm and the connection to the valve for movement, damage and drips. Note the supply pressure. Write down what you found and what you adjusted, so the annual leakage inspection has a record to compare against.
Adjust, inspect, replace: the order the manual implies
The manual's wording separates the actions. The monthly item is to inspect and adjust, so a float that sits too high or too low is a setting to correct first. The annual item is a leakage inspection, with a seat replacement only if necessary. That sequence keeps a setting problem from turning into a parts order.
If the valve still passes water after the float is set correctly and the seat has been looked at, then the valve assembly or its kit comes into the conversation. At that point the question is which kit matches your unit, and that is a serial number question.
How to read a make-up valve kit title
BAC's own replacement make-up valve kit page (BAC EU, node 1681) describes a PVC-body float valve (1-1/2 inch) and a polypropylene foam-filled float ball. Our listings are written differently, and the differences matter when you order.
Several of our kit titles end with "Less Ball" or "No Ball." Those kits are listed without the float ball, and the float balls are listed separately by size and material. If a title does not say "Less Ball" or "No Ball," confirm what the kit includes before ordering. Titles also show the valve material (PVC or brass), the valve size (1 inch or 1-1/2 inch) and a finish or hardware code such as Galvanized or SST. We list those details exactly as they appear in the titles and do not decode them further.
Float valve kits and float balls we list
| Component | Role in this issue | Where to find it |
|---|---|---|
| Float valve kit, PVC | Valve assembly; title says "Less Ball" | CK4011M3 — BAC PVC Float Valve Kit (Less Ball) SST |
| Make-up kit, 1 inch brass | Make-up valve kit; title says "No Ball" | RK0331M5 — BAC Make-up Kit (1" Brass Valve, No Ball) Galvanized |
| Float valve kit, brass | Valve kit; the title does not say whether a ball is included | RK0333M5 — BAC Float Valve Kit (Brass, 1") Galvanized |
| Make-up kit, 1-1/2 inch PVC | Make-up valve kit; title says "No Ball" | RK2301M5 — BAC Make-up Kit (1-1/2" PVC Valve, No Ball) Galvanized |
| Float ball, 8 inch | Float for the valve arm, listed separately | 280046 — BAC Float Ball 8" |
| Float ball, 10 inch pancake | Float for the valve arm, listed separately | 280045 — BAC Float Ball 10" Pancake |
| Float ball, 6 inch plastic | Float for the valve arm, listed separately | 280071 — BAC Plastic Float Ball 6" PA |
We have not matched any of these to a specific tower model. The titles tell you the valve size, material and ball size. Whether a kit or ball fits your unit is settled by your serial number.
Scope: The inspection intervals and the 15 to 50 psig figure come from the BAC Series 3000 O&M manual, p.26. They do not carry over to other BAC lines, which need their own O&M manual. The kit description from BAC EU is a product description, not a fitment statement for any particular model.
Before you order
Confirm your unit's exact model and serial number from its nameplate before ordering. Browse everything listed in our Baltimore Aircoil (BAC) parts collection, read our BAC parts guide, and search the part number in our site search. To confirm fit for a kit or float ball, contact us at help@totalhvacparts.com with your model and serial number.
Frequently Asked Questions
How often should I inspect the float valve on a BAC cooling tower?
On a Series 3000, the manual says to inspect the make-up valve assembly monthly and adjust it if necessary, and to inspect it annually for leakage, replacing the valve seat if necessary (p.26).
What is the make-up water pressure for a BAC cooling tower?
The Series 3000 manual says to maintain make-up water pressure at 15 to 50 psig (p.26). Check the supply pressure at the valve against that range if the basin level is wrong.
How do I adjust a cooling tower make-up valve?
The manual says to adjust the make-up valve assembly if necessary during the monthly inspection, and it names float position as one of the checks. The pages we reviewed give no adjustment dimensions, so follow your unit's manual for the setting.
How do I replace a BAC float ball?
Match the ball by size and material to the old one, and confirm against your serial number. We list an 8 inch float ball, a 10 inch pancake float ball and a 6 inch plastic float ball. Contact us if the old ball is missing.
Sources
- BAC Series 3000 Operation & Maintenance Manual, 3000_om_20200806, p.26
- BAC EU, replacement make-up valve kit page (baltimoreaircoil.eu, node 1681), cited as a product description only; not linked
Cooling tower work involves rotating fan and drive equipment, line-voltage electrical components and open water basins. 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.