Evaporative Cooler Float Valve and Solenoid Valve Guide: Filling Problems Fixed

An evaporative cooler float valve and the water inlet solenoid valve control how much water gets into your cooler. When either one fails, you’ll usually notice one of two problems: the cooler overflows and wastes water, or the tank doesn’t fill and the cooler blows warm air. This guide explains how each part works, how to tell which one has failed, and how to find the right replacement.

How water gets into an evaporative cooler

Mains water enters the cooler through a supply line. Depending on the model, the water level in the tank is controlled by:

• A float valve – a mechanical valve with a float, similar to a toilet cistern. As the tank fills, the float rises and closes the valve.
• A solenoid valve – an electrically operated valve that opens when the controller calls for water. Many coolers use a solenoid together with a float valve or a water level sensor.

The pump then lifts water from the tank to the pads, and a drain or dump valve empties the tank from time to time to flush out salts.

Signs of a faulty evaporative cooler float valve

• Water overflowing from the cooler or running constantly from the overflow.
• The tank fills too slowly or not at all.
• The float is stuck, cracked, waterlogged or crusted with scale.
• The water level sits noticeably higher or lower than normal.

Signs of a faulty solenoid valve

• The tank won’t fill when the cooler calls for water, even though the water supply is on.
• The valve clicks but no water passes (often debris or scale in the valve).
• Water keeps running after the cooler turns off (the valve is stuck open).
• A fault code on the controller related to water filling, on electronic models.

Replacement float valves by brand

Bonaire and Celair: the Bonaire cistern ball float valve (6050916SP) is our most popular float valve. See all Bonaire float valves.

Breezair, Braemar and Coolair: the vertical float valve (901114) and the adjustable horizontal float valve (905150). See Breezair and Braemar float valves.

Brivis: the Brivis Philmac float valve (B000414). See Brivis float valves.

CoolBreeze: the Fluidmaster 747 float valve (SP2027) and the magnetic float (SP2200). See CoolBreeze floats.

Replacement solenoid valves by brand

Breezair solenoid valve: the 24VAC solenoid valve (834320) suits a wide range of Breezair, Braemar and Coolair coolers, and the 12VDC solenoid valve (865607) suits models with 12V DC water management. Always check the voltage on your old valve. See Breezair and Braemar solenoid valves.

Bonaire solenoid valve: choose the 24V solenoid with dump/bleed fitting (6051636SP) or the 24V solenoid without dump/bleed (0080591SP) to match your old valve. See Bonaire solenoid valves.

Brivis solenoid valve: the 240V 3/4″ solenoid valve (B0081140) and the Elbi barbed solenoid valve (81019245). See Brivis solenoids.

CoolBreeze solenoid valve: including SP2640 and SP2031. See CoolBreeze solenoid valves.

How to choose the right part

1. Check your cooler’s brand and model on its compliance label.
2. Look at the old part: note any part number, the voltage printed on a solenoid (24VAC, 12VDC or 240V), and the fitting type and size.
3. Compare with the fitment and details on the product page.
4. If you’re unsure, contact us with your model number and a photo of the old part.

Is it the float valve, the solenoid or something else?

• Overflowing: usually the float valve (not closing) or a solenoid stuck open.
• Not filling: check the water supply tap first, then the solenoid, then the float valve.
• Tank empties by itself: the drain or dump valve may be leaking, for example the Bonaire dump valve (6001336SP).
• Tank is full but pads are dry: the pump is the likely cause. See our evaporative cooler pump guide.

Safety first

Most coolers are roof-mounted, and some solenoid valves run on 240V. Working at heights, on mains wiring or on the water connection should be done by a qualified technician, licensed electrician or plumber as required. Always isolate the power and water before starting.

Frequently asked questions

Why is my evaporative cooler overflowing?

The most common causes are a float valve that no longer closes (worn washer, scale or a damaged float) or a solenoid valve stuck open.

Why is my evaporative cooler not filling with water?

Check that the water supply tap is on and the inlet isn’t blocked, then check the solenoid valve and float valve. A drain valve stuck open can also stop the tank filling.

Can I use a 24V solenoid instead of a 12V one?

No. The solenoid must match the voltage your cooler’s control system supplies. Check the rating printed on the old valve.

How often should a float valve be replaced?

There’s no fixed interval. Replace it when it leaks, sticks or no longer holds the correct level, which happens sooner in areas with hard water.

Need a hand choosing the right evaporative cooler float valve or solenoid? Contact HotnCool with your cooler’s brand and model number and we’ll help you find the right part.