WashingMachines 2

Trends in Water Losses Resulting from Washing Machine Failures

DonanEngineering Appliance, Product & Component Failures, Articles, Component Testing, Forensic Engineer, Water Losses

Washing machine-related failures are one of the top 10 leading sources of residential water losses.[1]  While many such water losses are associated with the water supply hoses, water losses resulting from failures of the washer’s internal components often present a good opportunity for recovering damages through subrogation.  Many common washing machine failures are a continuous-leak condition, which creates the potential for extensive property damage.  Washing machines, and home appliances in general, have undergone significant design

Photograph 1: Location of the pressure switch, tubing, and drain pump on a washing machine.

Photograph 1: Location of the pressure switch, tubing, and drain pump on a washing machine.

changes in recent years, incorporating new electronic control systems and high-efficiency features for energy and water savings.  Along with new features and improved performance, these design changes have also introduced new failure modes and opportunities for leaks to occur.  Some of the most common washing machine components that fail and cause a leak are the solenoid-controlled water valves, pressure switches and associated tubing, and drain pumps and associated hoses (Photograph 1).  This article will focus on several recent trends in washing machine component failures responsible for extensive property damage.

The solenoid-controlled water valve is an electronically controlled valve that turns on and off the flow of water to the washing machine’s tub.  Solenoid valves are also used to control the flow of water in various other appliances, such as refrigerators and dishwashers.  The valves contain internal rubber seals that open and close when the valve operates.  If the rubber material the seals are not  properly formulated, they can break down over time and eventually allow water to flow unrestricted through the valve.  One particular issue affecting solenoid valves is rapid degradation due to exposure to chloramine in water supplies.  Chloramine is a water additive used for disinfection in municipal water systems.  Chloramine use has increased in recent years due in part to new drinking-water regulations developed to limit certain disinfection byproducts.[2]  Some manufacturers of solenoid valves offer chloramine resistance only upon request.  Numerous failures of solenoid valves resulting from premature degradation of the internal seals have been observed in recent years (Photographs 2 through 4).

Photograph 2: Solenoid valve's internal rubber seal in good condition.

Photograph 2: Solenoid valve’s internal rubber seal in good condition.

Photograph 3: Solenoid valve's internal rubber seal degraded.

Photograph 3: Solenoid valve’s internal rubber seal degraded.

Photograph 4: Solenoid valve's internal rubber seal degraded.

Photograph 4: Solenoid valve’s internal rubber seal degraded.

A pressure switch is used in most washing machines to measure the amount of water in the washer’s tub.  As the washer fills with water, air is trapped in a cavity connected to the tub and is forced through tubing to the pressure switch.  As the water level in the washer’s tub increases, the air pressure in the tubing and switch increases.  When the pressure reaches the switch’s setpoint, the switch opens, which shuts off the solenoid-controlled water valve.  Any leak or blockage in the pressurized air system will impede the switch from activating; therefore, the

Photograph 5: Tee fitting connected to a washing machine's pressure switch tubing.

Photograph 5: Tee fitting connected to a washing machine’s pressure switch tubing.

solenoid-controlled valve will remain active, causing the washer to overflow.  Some newer washing machines incorporate flow sensors and will shut off the flow of water if the volume of water flowing through the valve exceeds the capacity of the tub; however, most do not.  Several newer model Whirlpool washing machines incorporate two pressure switches as a redundant safety to prevent overfilling.  In these washers, the pressure switch tubing runs from the tub to a tee fitting, then to each pressure switch.  The additional connections in the pressure tubing introduce new potential leak locations in the pressurized air system.  In recent months, numerous water losses have resulted from these washers overfilling due to leaks where the pressure switch tubing connects to the tee fitting (Photograph 5).  GE brand top-loading washing machines, on the other hand, often overfill due to blockage in the pressure switch tubing near its connection to the tub.  This common failure has been observed in GE washer designs going back more than a decade and continues to be observed

Photograph 6: Blockage in the pressure switch tubing hear the connection to the washer's tub.

Photograph 6: Blockage in the pressure switch tubing hear the connection to the washer’s tub.

in models still in production (Photograph 6).  Many Maytag brand washing machines contain a small spring-action hose clamp on the pressure switch tubing’s connection to the side of the tub.  However, a commonly observed failure is for the tubing to separate from this connection or fracture at the location of the hose clamp (Photographs 7 and 8).  Once the tubing fractures or separates, the pressurized air will not reach the pressure switch, and the washer will overflow until it is manually shut off.

Photograph 7: Pressure switch tubing disconnected from the hose barb on the side of the washer's tub.

Photograph 7: Pressure switch tubing disconnected from the hose barb on the side of the washer’s tub.

Although a drain pump failure will not cause a washer to overflow, a leak in the pump housing or connected hoses can result in a continuous leak from the washer.  The drain pump is installed within the washer below the tub.  When a leak occurs at the drain pump, the water will drain from the tub, and in many cases, the washer will continue to add water to the tub in an attempt to continue filling the tub to the desired water level.  Some newer washers incorporate a recirculation pump as well as a drain pump as part of a low water consumption design.  On many Whirlpool Cabrio, Maytag Bravo, and Kenmore Oasis brand washers (all manufactured by Whirlpool), the basket and laundry detergent/bleach strainers have been redesigned with larger openings that will allow coins and other objects to pass through and enter the drain pump.

Photograph 8: Fracture in the pressure switch tubing at the connection of the tub.

Photograph 8: Fracture in the pressure switch tubing at the connection of the tub.

These objects will circulate within the pump, eventually fracturing the plastic pump housing and causing a leak.  The replacement pump for these washers contains reinforcing ribs on the plastic housing that were not present on the original pumps (Photographs 9 and 10).  However, fractures have also been observed in the new-style pumps with the reinforcing ribs.

Photograph 9: Fractures in the plastic drain pump housing.

Photograph 9: Fractures in the plastic drain pump housing.

A recent failure trend in Samsung brand washing machines involves fractures in the drain pump’s mounting bracket. On these washers, the drain pump is mounted to the bottom of the washer’s tub. Over time, the motion and vibration of the washer’s tub initiate fractures in the drain pump’s mounting bracket (Photograph 11).  These fractures eventually propagate completely through the bracket until the pump is hanging from the hose connection to the tub.  The hose connection eventually separates due to the motion of the tub, and the water leaks from the washer’s tub.

Photograph 10: Fractures in the redesign drain pump housing with reinforcing ribs.

Photograph 10: Fractures in the redesign drain pump housing with reinforcing ribs.

In this case, the replacement drain pump has been redesigned such that it mounts to the washer’s bottom panel, eliminating the stresses on the bracket.  Samsung has released a service bulletin covering this failure and the installation of the redesigned pump.

One common failure on some Maytag washing machines is for the hose from the drain pump to separate from the bottom of the washer’s tub during operation (Photograph 12).

Photograph 11: Mounting bracket fractured and separated from the drain pump.

Photograph 11: Mounting bracket fractured and separated from the drain pump.

The spring-action hose clamp used on the connection and the positioning of the connection during manufacturing make it unable to withstand the stresses experienced during several years of operation.  If this failure were observed in an isolated instance, it may appear to be the result of inadvertent loosening of the connection during a repair or due to inadvertent abuse.  However, numerous Maytag washers of the same design, manufactured during the same timeframe, have experienced this same failure mode.  In many cases, the washer had never been disassembled for maintenance or repair.

As washing machine designs continue to evolve, past issues are sure to be resolved, and new failure modes are sure to appear.  Many times, investigation of a single occurrence provides a minimal amount of data to identify the root cause of a failure.

Photograph 12: Drain hose separated from the bottom of the washer's tub.

Photograph 12: Drain hose separated from the bottom of the washer’s tub.

Establishing a trend of a particular failure mode is always helpful and sometimes necessary to identify the factors contributing to a failure and for successfully subrogating a manufacturer’s defect as the cause of a water loss.