The liquid drainer is a float valve that opens to allow liquid to pass, but closes when the liquid level drops. It is a small vapor bypass to prevent vapor binding of the valve. The liquid drainer controls a different behavior of the pressure in the coil during defrosts in comparison to the pressure-regulating valve. The regulating valve allows the pressure in the coil to rise to its pressure setting, where it remains. With the drainer, the pressure in the coil will continue to rise until it nearly reaches the pressure of the incoming defrost gas. Equipping the coil with the bypass valve is particularly critical so that high coil pressure is not suddenly discharged into the suction line, when defrost terminates.