Tumble dryer taking hours to dry
The most common complaint about modern dryers, and on a heat pump machine it is usually the machine working exactly as designed. Here is how to tell that apart from a real fault.
What it usually means
Before anything else, work out which kind of dryer you own, because the answer to this question is completely different depending on the answer to that one.
If you have replaced a vented or condenser dryer with a heat pump model in the last few years, and the new one takes two or three hours where the old one took ninety minutes, nothing is wrong. That is what the machine is. A heat pump dryer recycles its own warm air instead of heating fresh air and throwing it away, which is how it uses around half the electricity — and the price of that efficiency is a cooler, longer cycle. Manufacturers are unusually direct about this in writing. AEG's wording is that heat pump dryers "give very gentle and energy-efficient drying at low temperatures, but the drying time will be somewhat longer. This is normal and not a malfunction in any way."
The same manufacturer notes something people do constantly without realising the cost: opening the door part way through to check on the washing "will extend the cycle by at least half an hour each time the door is opened", because the heat pump takes a long time to get back up to working temperature. If you check on it twice, you have added an hour yourself.
So the useful question is not "is three hours too long". It is **has this machine got slower than it used to be**. A dryer that has always taken three hours is behaving normally. A dryer that took two hours last year and takes four now has something wrong with it, and the something is nearly always airflow.
There is one more thing that is not the dryer's fault at all: how wet the washing was when it went in. Water the washing machine did not spin out has to be evaporated by the dryer, using electricity, slowly. AEG ask for a minimum spin of 800 rpm before drying, and going from a 1000 rpm spin to a 1400 rpm one takes a surprising amount of time off the drying cycle for nothing.
How to narrow it down
Work through these in order.
Has it got slower, or has it always been like this?
This is the question that decides everything else. A machine that has always taken this long, particularly a heat pump one, is probably fine and the rest of this page will not help much. A machine that has gradually slowed over months has a developing airflow problem, and that is worth chasing.
When did you last clean the filter — and the other one?
Most people know about the fluff filter in the door. Far fewer know that condenser and heat pump machines have a second, finer filter behind a flap low down at the front, and behind that a block of metal fins that the entire airflow passes through. If you have never opened that lower flap, open it now. It is the single most common reason a dryer slows down.
What spin speed did the washing machine finish on?
Below 800 rpm and you are asking the dryer to remove water the washing machine should have removed for free. A faster spin costs seconds of electricity; evaporating the same water in the dryer costs a great deal more, and adds real time to the cycle.
Where is the machine, and how cold is that room?
A dryer in an unheated garage or outhouse in winter will struggle. Manufacturers specify a working range — AEG give above 5°C and below 35°C, with 19 to 24°C as the optimum — and a heat pump machine is more sensitive to this than a vented one, because it is moving heat around rather than simply making it.
Is anything covering the vents or the floor underneath?
Check the ventilation opening in the base is not sitting on a rug or a fitted mat, that the machine is not shut in a cupboard with no air exchange, and on a vented dryer that the hose behind it is not crushed against the wall or kinked. All of these strangle the airflow the machine depends on.
Do you use fabric conditioner?
It leaves a film on the two metal sensor strips inside the drum that the machine uses to tell when the load is dry. Coated strips read damp cloth as drier than it is, or dry cloth as still wet, and the cycle runs on. Wipe them with a little white vinegar and cut back on conditioner for loads that go in the dryer.
Is there a fault code showing?
Then this is not a mystery any more and you should look the code up. AEG treat a cycle running past four and a half hours with a code showing as a genuine moisture sensor fault rather than a slow machine, and their heating and airflow codes point somewhere specific too.
Codes commonly shown with this
- E60AEGThe dryer is not heating. AEG’s own page for this code is circular — it defines E60 by telling you the machine displays E60 — so here is what it actually covers.Get it checked
- C6AEGThe moisture sensor is not reporting properly, and AEG give a specific symptom: the cycle runs on past four and a half hours instead of finishing.Get it checked
- Condenser lightAEGNot a fault code but a maintenance reminder, and the most important one on the machine. The condenser is furring up with lint and AEG tell you not to run it like that.Get it checked
- F66MieleThe airflow fault, and the code most often described wrongly elsewhere. Miele publish eight causes and seven of them are yours to fix — including a filter that is simply worn out.Get it checked
- F55MieleThe machine gave up after three hours with the washing still damp. Miele name a cause most people would not think of: the spin speed on your washing machine.Get it checked
- E01BoschA blockage in the filter or heat exchanger. Bosch publish an eleven-step fix for it that most of their current machines cannot accept.Get it checked
When it is urgent
Take care
What it costs
Typical repair cost
£0–£180
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Get an engineer to look at this
We do not pass enquiries to a repair firm, so there is no form here. When you book a qualified appliance engineer, tell them the make, the model and the exact code or message on the display, and ask whether they carry parts for this make — that is what turns one visit into a repair rather than a quote.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.