At many of my home inspections I find condensate pumps installed to discharge the condensate water produced by the air conditioning system and/or high efficiency gas furnace from the home. The pumps contain small reservoirs that have a float switch installed, which activates the pump when the water accumulates to a set point in the reservoir. The condensate pumps are frequently located in crawl spaces and tend to be forgotten. Unfortunately, like all mechanical devices the pumps can stop working for a variety of reasons. When they stop working, the condensate water spills into the crawl space. The wet area quickly becomes a host site for fungal growth and contributes to raising the humidity level throughout the crawl space encouraging additional fungal growth elsewhere. Condensate pumps should be cleaned and inspected for proper function as a regular part of an annual home maintenance program.
There are condensate pumps available that come equipped with a safety switch. The safety switch, when properly wired into the air conditioning system, automatically turns the air conditioning system off when the condensate pump malfunctions. Turning the air conditioning system off when the condensate pump malfunctions, stops condensate water from being produced and overflowing from the reservoir into the crawl space. Notice the two small wires coming out of the right side of the condensate pump pictured below, those are for the safety switch and are supposed to be connected to the control circuit for the air conditioning system. Unfortunately the pump was never wired correctly, and as a result a fungal garden grew when the condensate pump continued to overflow and saturate the crawl space. I always recommend a condensate pump with safety switch be properly installed when the unit will be placed in a crawl space.