Abstract: A combination check valve and fluid trap device for connection to the outflow aperture of a condensate moisture drain system on an air conditioner, ice maker, cooler or like apparatus, the device comprising a ball float sealingly seated on a float seat within a housing, the float seat being connected to the outflow conduit of a generally U-shaped fluid trap having an inflow conduit for connection to the drain system, whereby water and gas are prevented from entering the fluid trap through the outflow conduit but excess water will move the ball float from the float seat to allow water to flow out of the outflow conduit. Preferably the fluid trap is provided with rotation means whereby the longitudinal axis of the inflow conduit can be adjusted relative to the longitudinal axis of the outflow conduit so that the two axes are not aligned in parallel.