Soft water can be too pure for the cooler's probes

Why would a cooler say there's no water in a full tank?

The probes find water by passing a tiny current through it. Water with almost no salt in it barely carries a current, so the probes can miss it altogether.

Seeley's own diagnostic spells it out. If the LED stays lit while the probes are sitting in water, they're reading less than 20 µS/cm. In Seeley's words, the water has very little salt content.

Seeley's FC02 cause list says it outright, too. "Water too pure for the probes to sense water is present."

That gives you a cooler reporting no water while it sits in a full tank, with nothing wrong with it. Almost nobody writes about it.

How soft does the water have to be?

Softer than Melbourne mains on average. Using the rough conversion in the table further down, the 55 mg/L mains average and the 33.1 mg/L rainwater average both work out well above 20 µS/cm. It's rainwater at the bottom of its range, down towards 2 mg/L, that sits under it.

So on a rainwater supply, suspect it early. On mains, treat it as something to rule out rather than the first answer.

How do you tell pure water from a real fault on site?

1. Look in the tankIf there's water at the right level and the controller says there isn't, you're already most of the way there. On a Breezair, the level is set 5 mm above the float valve base.
2. Check what's feeding itA rainwater tank pushes you toward the too-pure explanation. Inner and western suburbs mains is soft enough to keep it on the list. Bore water pushes you the other way entirely.
3. Then rule out slow fillFC02 means water not detected within 20 minutes, so low supply pressure throws the same code for a completely different reason. The minimum is 100 kPa.
4. Clean the probes anywayA coated probe and pure water give the same result, and one of the two is free to rule out.

Which water supply suits an evaporative cooler best?

Rainwater, and the Commonwealth research says so plainly. Its dissolved solids can be as low as 2 mg/L. A survey of 35 tanks found 9 to 160 mg/L, with a mean of 33.1 mg/L. It cools better and needs less dumping, and the research recommends it for evaporative coolers where you've got it. The catch is the one above. The purer it is, the more likely the probes can't see it.

Hard water in Victoria is a regional and bore water story, not a metro one. On bore water, Seeley switches the salinity circuit off altogether and drains on a timer instead. That shows you how different bore water is.

What bleed and dump rates should you expect?

• Constant bleed is adjustable from 2 to 45 L/hr. Most residential installations sit at 3 to 5 L/hr.
• Some manufacturers ask for at least 10 L/hr, even where water quality is good.
• Seeley WaterManager opens the drain and lets out about 6 to 8 litres.
• On bore water the salinity circuit is disabled, and 6 to 8 litres drains every 65 minutes of running.
• Sump capacity on top and down discharge single fan units is 10 to 12 litres.

If the customer asks about water use, evaporation alone on a Melbourne design day at full fan speed is 58.6 L/hr for a unit moving 9,360 m³/h, and 101.4 L/hr for one moving 16,200 m³/h. At average half speed, roughly halve those figures. Across a year, whole house evaporative use works out at 2 to 10 per cent of a typical Australian household's water use.