The short answer
A heat-pump dryer contains a refrigeration circuit, so it makes a noise a vented machine simply does not have — and that is the first thing to rule out. Ranked first on this platform: The heat-pump compressor. The checks below follow that ranking, and the first of them need no tools and no panel removed.
What you observe
- A continuous low hum through the whole cycle on a machine that dries perfectly well — Correct drying plus a steady hum is the platform, not a defect.
- A sharp ticking or clattering that only happens while the drum turns — A noise that starts and stops with the drum is something travelling with it.
- The noise changes when you lean on a corner of the machine — A noise that responds to your weight is a mounting noise.
- NEAR MISS — a rattle from the ducting behind the machine rather than inside it — Loose ducting and a flapping vent hood are outside the appliance and are dealt with differently.
Causes, most likely first on this platform
- The heat-pump compressor — A heat-pump dryer contains a refrigeration circuit, so it has a compressor that a vented machine does not. It ranks first on this platform because there is a compressor inside this machine that hums continuously through the cycle, and owners moving from a vented dryer routinely report that hum as a fault when it is the platform doing exactly what it was designed to do.
- Something loose in the drum or the blower — Coins, buttons and pen caps work out of pockets, past the drum seal and into the blower housing. It ranks second here because the machine expects the owner to open a plinth flap and service a filter and a foreign-object trap on a schedule, and on most machines that has never been done.
- The machine not standing solidly — A dryer on three of its four feet rocks under an unbalanced load and drums against the floor. On a stacked or plinth-mounted installation the same movement is transmitted into the cabinet around it and amplified. Ranked third: worth checking once the causes above have come back clean.
- Worn drum glides or a worn felt seal — The drum rides on plastic glides and felt seals that are designed to wear. It ranks fourth rather than higher: real on this platform, and less common than the causes above it.
Check in this order, and why
- Check whether the load is drying properly before chasing the sound — A machine that dries correctly has no fault to find. It leads because it tests the top-ranked cause.
- Run the machine empty for a moment and listen, then check the lint trap housing — It separates the load from the machine in one run. Tests the second-ranked cause.
- Push the top corners diagonally and watch for a rock — Seconds, and it is free to correct. Tests the third-ranked cause.
What an owner can safely check
- Empty the drum, check the lint filter housing with a torch, and feel round the drum seal — Anything you can reach from inside comes out without tools.
Tools: torchAbout 15 min
- Level the machine on its feet so no corner moves under hand pressure — Check it with a load in, not empty.
Tools: spirit levelAbout 20 min
- STOP at the first panel that needs a tool, and write up what you found — A technician who arrives knowing which checks came back clean spends the visit fixing rather than repeating them.
Before you open anything
Safety
Unplug the dryer or switch off its breaker before removing any panel; on a gas machine, close the gas shut-off valve as well.
When to call a technician
Call once the noise has been traced behind a panel — a drum support, an idler or a bearing is a strip-down rather than an adjustment.
Nearest pages of this class
What this page does not cover
This page is written for the Miele dryer as a class, not for one family or one model line. Where a family- or model-specific page exists for your unit, that page is the more specific answer and the one to read first. Deliberately not here: part numbers, wiring colours and disassembly order, which differ by family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
