How Often Should You Clean a Tumble Dryer?

Almost everyone knows about the lint filter. Considerably fewer know that condenser and heat pump dryers have a second filter, usually behind the plinth, that also needs cleaning. And very few have ever looked at the heat exchanger behind that.

The consequence isn't dramatic. The dryer doesn't break — it just takes longer and longer, costing more each time, until eventually someone concludes it's worn out. A large proportion of dryers replaced for being "slow" were simply blocked.

The Short Answer

A maintenance schedule that takes about ten minutes a month:

Job	How often	Time
Lint filter in the door	Every single load	30 seconds
Wash the filter mesh in water	Monthly	2 minutes
Secondary filter / condenser unit	Monthly	5 minutes
Water tank and its housing	Monthly	2 minutes
Heat exchanger fins (heat pump)	Twice a year	15 minutes
Vent hose and wall vent (vented)	Twice a year	15 minutes
Drum and door seal wipe	Occasionally	2 minutes

The one that matters most is the lint filter, every load, without exception. It's both the biggest performance factor and the single most effective fire precaution available to a dryer owner.

The one nobody does is the secondary filter on condenser and heat pump machines. Check your manual for its location — it's usually behind a flap at the bottom front.

What Actually Matters

Airflow is the whole mechanism. A tumble dryer works by moving heated air through the load, picking up moisture and carrying it away. Every restriction in that path — filter, condenser, hose, vent — reduces the airflow and therefore the drying rate.

The dryer doesn't compensate by working harder in any useful sense. It just runs for longer, which means more electricity for the same result.

Lint accumulates where you can't see it. The filter catches most of it. What escapes settles in the ducting, the condenser fins, the heat exchanger and the cabinet interior. That's why the decline is gradual — it's a slow accumulation in places nobody looks.

Lint is genuinely flammable. This isn't scaremongering. A dryer generates its own supply of fine, dry, combustible fibre, and it does so next to a heating element. No other domestic appliance has that combination, which is why dryer fire guidance is more emphatic than for anything else in the house.

Detailed Analysis

The lint filter, and the bit people miss

Every load. It takes thirty seconds and it's the difference between a dryer that works and one that doesn't.

The part people miss is that a filter can look clean and still be blocked. Fabric conditioner and dryer sheets leave an invisible film on the mesh, and that film restricts airflow considerably while the filter appears spotless.

The test: hold the filter under a running tap. If the water sits on the mesh rather than running straight through, it needs washing. Warm water, a drop of washing-up liquid and a soft brush, then dry it completely before refitting — a damp filter in a dryer is not a good idea.

Once a month is about right for the wash, more often if you use conditioner heavily.

Some dryers have a second lint filter inside the door frame or in the drum opening. Worth checking the manual, because a filter you don't know about doesn't get cleaned.

The secondary filter and condenser unit

This is the one that surprises people, and it applies to condenser and heat pump dryers rather than vented ones.

Behind a flap at the bottom front of the machine — usually released by a catch or a couple of clips — sits either a removable condenser block or a foam and mesh filter assembly, depending on the design.

On older condenser dryers this is a metal block with fine fins. It slides out, and it should be rinsed under a tap until the water runs clear. Lint packs into the fins densely and it's often a genuinely alarming amount the first time.

On heat pump dryers there's typically a foam filter and a mesh, both of which come out and rinse clean. The foam needs to be completely dry before refitting.

Monthly is a reasonable interval. If your dryer has gradually got slower over the past year and you've never opened this flap, this is almost certainly why.

The heat exchanger on heat pump dryers

Deeper in, and the source of the classic heat pump complaint — a machine that was fine for two years and now takes five hours.

Behind the secondary filter is the evaporator, a block of very fine aluminium fins. Lint that gets past the filters settles on these, and because the fins are close together it packs solid over time.

Access varies enormously by model. Some manufacturers make it user-serviceable with a removable panel. Others treat it as a sealed assembly requiring an engineer. The manual will tell you which yours is, and it's worth knowing before buying.

Where you can get at it, clean gently. A soft brush and a vacuum with a brush attachment, working in the direction of the fins. They're thin aluminium and bend easily, and bent fins restrict airflow permanently.

Never use water on the evaporator unless the manual specifically says to.

Twice a year is about right, or whenever drying times start creeping up.

Vented dryers: the hose and the wall vent

Vented machines have no condenser to clog, but they have a duct that does.

Disconnect the hose from the machine and from the wall outlet, and look through it. Lint builds up along its length, particularly at bends and in any sagging section. Pull a cloth through it, or use a vacuum.

Then check the outside. Wall vents have a flap that should open when the dryer runs and close when it doesn't. They get blocked by lint, by cobwebs, and occasionally by birds nesting behind them. A flap that no longer opens freely restricts everything upstream of it.

Twice a year, and before the winter when the dryer starts getting heavy use.

The water tank and its housing

A small job that prevents a specific complaint.

Condenser and heat pump dryers collect water in a removable tank. The tank itself gets emptied regularly, but the housing it sits in accumulates a slimy residue over time, and that's what produces the musty smell some dryers develop.

Take the tank out, wash it with warm soapy water, and wipe the recess. Monthly, alongside the condenser check.

Worth noting that the collected water is distilled and is genuinely useful for steam irons — one of the few pieces of household advice that costs nothing and works.

Real-World Considerations

The cost of neglect is measurable. At the Ofgem capped rate of 26.32p per kWh for October to December 2026, a properly maintained heat pump dryer uses around 1.6 kWh a load — about 42p. A blocked one running 40% longer uses closer to 2.2 kWh, about 58p. Over 150 loads a year that's roughly £24, every year, for a job that takes ten minutes a month.

On a vented dryer the figures are larger, since the baseline consumption is higher.

Fabric conditioner is the main culprit behind filter films and sensor coating, and it's worth reconsidering whether you need it. Wool dryer balls do a similar job of separating the load without depositing anything.

Households with pets or with a lot of towels generate far more lint than average, and the intervals above should be shortened accordingly. Fleece and microfibre are also heavy shedders.

Where a dryer lives matters for maintenance too. A machine in a garage or an outbuilding accumulates dust as well as lint, and dusty environments clog condensers faster.

And if a dryer has been neglected for years, the first proper clean can produce a dramatic improvement — drying times sometimes halving. That's worth knowing before deciding a slow machine has reached the end of its life.

Common Mistakes Buyers Make

• Cleaning the filter "when it looks full". Every load. Conditioner film blocks airflow while looking clean.
• Never opening the bottom flap. The secondary filter on condenser and heat pump dryers is the most commonly neglected part of the machine.
• Refitting a damp filter. Wash it, then dry it fully before it goes back.
• Using water on a heat pump evaporator. Unless the manual says to, don't. Brush and vacuum only.
• Bending the evaporator fins. Thin aluminium, easily damaged, and bent fins restrict airflow permanently.
• Ignoring the vent hose on a vented dryer. Lint builds up along its length and at every bend.
• Forgetting the wall vent flap. Cobwebs, lint and occasionally nesting birds.
• Concluding a slow dryer is worn out. Check every filter first — the improvement after a proper clean can be dramatic.

Alternatives Worth Considering

If your heat pump dryer's evaporator isn't user-accessible, an engineer visit every couple of years is worth budgeting for. It's a modest cost against the running cost of a progressively blocking machine, and against replacing it early.

Wool dryer balls instead of conditioner removes the main cause of filter films and sensor coating, while still separating the load and slightly reducing drying time.

For vented machines, replacing a corrugated hose with rigid or semi-rigid ducting reduces lint accumulation substantially — smooth walls give it nothing to catch on.

And when buying, checking whether the heat exchanger is user-serviceable is a specification worth asking about. It rarely appears in marketing material and it makes a real difference to how the machine ages.

Frequently Asked Questions

How often should you clean a tumble dryer filter?

Every load. Wash the mesh in water monthly to remove the invisible film left by fabric conditioner.

Where is the second filter on a condenser dryer?

Usually behind a flap at the bottom front of the machine. Check the manual — designs vary and many owners don't know it exists.

Do heat pump dryers need servicing?

They need the evaporator cleaning periodically. Some are user-accessible, some require an engineer. The manual will say which.

Why is my tumble dryer taking so long?

Almost always restricted airflow. Work through the lint filter, the secondary filter, the condenser or heat exchanger, and on vented machines the hose and wall vent.

Can you use water on a heat pump evaporator?

Only if the manual says so. Otherwise brush and vacuum gently in the direction of the fins.

Does a blocked dryer cost more to run?

Yes. A machine running 40% longer than it should costs roughly £24 a year extra on a heat pump model, more on a vented one.

Final Thoughts

The lint filter every load is non-negotiable, and it's the one most people already do. The gap is everything behind it — the secondary filter, the condenser, the heat exchanger, the vent — and that's where slow drying actually comes from.

Ten minutes a month covers all of it. Set a reminder for the first weekend of the month and do the condenser and the water tank together; do the deeper clean when the clocks change, twice a year.

If your dryer has got noticeably slower and you've never opened the bottom flap, do that before anything else. It's the single most likely explanation and the improvement is often immediate.