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How do washer dryers work?

A washer dryer is a machine of convenience, letting you wash and dry in one go, saving space over having separates. Yet, as convenient as they are, washer dryers are also more expensive to run and work in a different way to a regular tumble dryer. Here, I’ll explain how they work.

Washing machine

A washer dryer is a perfectly normal washing machine. In fact, they work in exactly the same way as a normal washing machine. There’s a standard detergent drawer at the top, which you use for washing liquid and fabric softener.

Cold water comes into the back and is heated internally based on the temperature that you set. Based on the wash programme selected, the drum is moved in a certain pattern, with detergent being mixed in before the final rinse and spin cycles.

At the end of a wash programme, your washing is ready in exactly the same way as if you’d used any regular washing machine.

Tumble dryer

It’s the tumble dryer side that’s completely different for washer dryers. Smaller drums than with regular tumble dryers and the need to put two functions into a case that’s the same size as a freestanding washing or tumble dryer means that the drying side is different.

The big difference is that most modern tumble dryers are heat pump models that condense water from your clothes into a tank at the top of the machine, reusing the heat extracted.

With a washer dryer, there’s no water tank. Instead, water from your clothes has to be extracted and pumped out of the washing machine’s drainage pipe.

To do this, the washer dryer has a heating element that warms the drum. The heat this generates causes water in your clothes to turn to steam. Steam rises into a vent and is pushed through it via a fan. You can see this assembly in the picture below.

Washer Dryer heating unit

This steam gets taken into a condenser tank (usually a plastic tub at the rear of the machine), which cools steam turning it back into water. With a regular tumble dryer, cold air is used in the chamber, but with a washer-dryer cold water is used instead, taken from the standard water inlet.

While this means that you can fit a washing machine and tumble dryer into a smaller space, it means that running costs are increased, as you also have to account for water usage as well as electricity.

Once water has been condensed, it runs out the bottom of the machine and is pumped out in the standard way.

Due to this design, washer dryers do not have lint filters, and everything gets washed out through the machine. This can lead to washer dryers getting clogged up with fluff, making them less efficient or stopping them working entirely.

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