Thread: Water Detection Device

I was inspecting an air handler in the attic of today’s home. The air handler had a secondary condensation pan with a water detection float device beneath the unit. My shirt sleeve snagged the float device and pulled it. The system did not shut off. My curiosity got the best of me and I raise the float device and the system still did not shut down.

My question is do these floats have to absorb water to shut down the system like a rain sensor on an irrigation system, or was the water float likely not wired properly or defective? Should I make a point to check the the water detection devices on air handlers in attics?

Thanks in advance.

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A float "floats" and lifts the arm off the micro switch, which shuts the unit down ... when wired in properly.

I've seen some which only shut the condenser unit off, but left the air handler running. Could that happened?

The ones I have seen only shut off the condenser. I have been seeing a new design that does not have a float, it works on contact with water.

Thanks Jerry,

I was waiting for you to chime in.

I guess the only way I would be able to tell if the condenser shuts down (since i would be in the attic) would be to get a temp from the supply plenum after a minute or so, and see if it increases.

As always Sir, thank you for your help.

Scott,

These may be that kind, they appear to raise up and down like a float, however they have a fabric of sorts on the end of them. I was thinking they may be like the rain sensors on some irrigation systems.

Thanks guys, i'll do some research.

Matt,

There are many types.

Some old versions had a arm which rested on an aspirin tablet. Water got in the pan, dissolved the tablet and the switch shut the unit off.

Newer ones have an actual float which floats up and shuts it off.

Even newer ones (like Scott mentioned) have an electronic device which measures (capacitance? resistance?) between two metal contacts and shuts the unit off when water contacts both of the metal contacts - supposed to anyway, I've always seen those drowning in water 'cause they can't swim, yet the units still run just fine - until the pan overflows because they did not work.

"I guess the only way I would be able to tell if the condenser shuts down (since i would be in the attic) would be to get a temp from the supply plenum after a minute or so, and see if it increases."

Or, you could go outside and find the unit either operating or not.

I do not test the floats. I've been told that they are only good for a few 'trips'. - dont wan't my test to be the last one - besides I can't judge the proper amount of pressure to assert on them.
I guess the only way to test the pan sensors would be to pour water on them. ---- No, Rich, don't p--- on them - the acid will rust the pan!!

Even when I see a float switch I still recommend a secondary condensate line. Good Idea or not needed?

Originally Posted by David Banks

Even when I see a float switch I still recommend a secondary condensate line. Good Idea or not needed?

Because of your choice of words ...

Yeah, I say it's a "good idea" and "needed" (it sure could be "needed"), but, the reality is that the code does not require "good ideas" and therefore it is not "required".

I have been doing many home inspections on new homes built by a builder in my area. They have had to replace several garage ceilings. They have secondary condensation pans, however they have the pan drain lines plumed into the main condensation line rather than to a conspicuous place.

Some of the secondary pans filled with water and were not properly supported, this caused the water to pond towards the center of the pan actually bending the pans, allowing the water to pour over without even touching the float.

Having air handlers in attic is just a poor design in my opinion.

Depending on how the float switch is wired into the low voltage circuit it might only break the Y circuit from the thermostat shutting down the outside unit.

If the installer wired it to break the R circuit then that would shut down everything including the indoor fan.