Cassette Leaking After Heavy Rain: Float Switch Missed Load
A cassette leaks after heavy rain and the safety device is called useless. Whether it failed or was asked for the impossible.
By Team Snowflake | Updated 24 Aug 2026
Teaching case based on recurring Snowflake service patterns; identifying details are combined.
How this presents
Staining on a ceiling below a unit that does shut itself down when the pan fills. The shutdown happens reliably every time. Damage appears anyway, and it follows periods of heavy rain rather than heavy use.
- Setup
- LG Cassette4-6 yearsCondoDowntown Core
- Misread as
- A safety device that has failed, leaving the property with no protection at all.
- Check first
- Whether the damage follows heavy rain rather than heavy use
What else produces this
A device that operates every time is not a failed device, so testing it again answers nothing. What matters is the gap between the water reaching the trigger level and the water reaching the edge, measured against how fast it is arriving. Under ordinary conditions that gap is comfortable. Under a rate the arrangement was never sized for, the pan reaches its edge before the shutdown has taken effect, and the sequence is correct throughout.
A shutdown occurring reliably every time removes the protective device from suspicion.
Damage following heavy rain rather than heavy use points at an inflow the drainage was never sized for.
Water entering the drain path from outside during rain adds to what the coil produces.
A pan reaching its edge before the shutdown takes effect explains damage sitting alongside working protection.
Why it happens
A shutdown stops the unit producing more water. It does nothing about water already in the pan or arriving from elsewhere, and it takes time to have any effect at all. Where rain finds its way into the drain path, the inflow rate is far higher than anything the coil produces, so the level rises faster than the sequence was designed for. Everything operates correctly and the ceiling still gets wet.
What resolution involves
Rain is kept out of the drain path, at the outlet or wherever it is entering, so the protection is never asked to handle a rate it cannot. The distinction is worth holding onto generally. Protection that operates late is not a faulty device, it is an inflow that was never anticipated, and replacing the device changes nothing about that.
How to tell it worked
Behaviour during heavy rain rather than a bench test of the shutdown itself. The device passes any test put to it; what has to be proven is that the pan no longer fills faster than the shutdown can help.
Before you approve a quote
Correct but late is still a wet ceiling
- A device that operates every time is not the fault. Test the rate of inflow instead.
- A shutdown stops production. It does not remove water already there or arriving from elsewhere.
- Damage that follows the weather rather than usage points at water entering from outside.
Questions this case answers
Ceiling cassette drips only during heavy rain: is the drain clogged?
What is a float switch and how can it cause a leak?
Does a leaking cassette mean the drain pan has cracked?
Can a leak that only happens in a storm be reproduced during a visit?
Ready to get started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.