Overview Of Cooling Tower Makeup Water Valve

A cooling tower makeup water valve (also called a float valve or make-up control valve) automatically adds fresh water to the cooling tower basin to maintain the correct water level.

Purpose of a Cooling Tower Makeup Water Valve

It compensates for:

* Evaporation losses (main loss)

* Drift losses

* Blowdown (bleed-off)

Without a proper makeup valve, the basin level will drop and the condenser water pump may cavitate.

How the Cooling Tower Makeup Water Valve Works

1. Basin water level drops

2. Float or level sensor detects low level

3. Valve opens and admits makeup water

4. Basin level returns to set point

5. Valve closes automatically

Common Types of Cooling Tower Makeup Water Valve

1. Mechanical Float Valve (Most Common)

* Simple, reliable, low cost

* No electricity required

* Used in small to medium cooling towers

Typical materials: Brass, stainless steel, plastic (PVC/ABS)

2. Electronic Level Control Valve

* Uses level probes or ultrasonic sensors

* Solenoid or motorized valve

* High accuracy

* Used in large HVAC or industrial systems

3. Pressure-Reducing Makeup Valve

* Integrated pressure regulator

* Protects valve from high city-water pressure

* Often combined with float valve

Typical Installation Location Of Cooling Tower Makeup Water Valve

* Mounted on the side of the cooling tower basin

* Connected to city water / RO / softened water

* Float arm positioned to match normal operating level

Key Selection Parameters Of Cooling Tower Makeup Water Valve

Parameter	Typical Value
Water pressure	2–6 bar
Flow capacity	Sized to refill basin within 30–60 min
Material	Brass / SS304 / SS316 / Plastic
Connection	DN20–DN50 (¾″–2″)
Control type	Float or electronic

Cooling Tower Makeup Water Valve vs Blowdown Valve

Makeup Valve	Blowdown Valve
Adds water	Discharges water
Maintains level	Controls TDS
Level-based	Conductivity-based

Both are required for proper cooling tower operation.

Common Problems & Fixes About Cooling Tower Makeup Water Valve

* Valve stuck open → Basin overflow → Clean or replace valve

* Valve not opening → Low basin level → Check float or supply pressure

* Water hammer → Add pressure reducer or slow-closing valve

* Scaling on valve → Improve water treatment

Best Practices

* Install a strainer upstream

* Provide isolation valve for maintenance

* Use softened or RO water to reduce scaling

* Periodically inspect float movement