Dryer Full of Dust? - A service guide - Miele Tumble Dryer

[dishman]

Because I was curious, I decided to compare how this dryer [The Miele] operated with the one my family has been using for the last 30 years or so.

It is a Hoover Logic, which apparently has some kind of autosense.

The autosense does actually work on occasion but stuff has to get bone dry. The timer is a bit dodgy, so it can sometimes go through an 120mins in 30mins, but that does not really bother me as it stops it being left on for longer than it needs to.

I must point out that this has been kept in a non-weather tight environment for 30 years. A lean-to with a leaky roof. It also went a number of years with no use.

However, other than the time fault, it still works perfectly!

So, how will the levels of dust compare? 30 years for the hoover in a damp and dirty lean-to vs the Miele which was inside an insulated porch and used for only a few years.

As this had never been opened in 30 years I expected the worst. Due to the damp nature of where it has been kept, there was a fair amount of cosmetic rust at the bottom. But nothing that had compromised the casing.

The lid was a pain to get off as it is very tightly held at the front, by two brackets that slot into the lid frame. Opening it up, I feared the worst as to the amount of dirt I would find....

But....to my surprise!



Not too bad so far. A bit of dust on all the control circuits....but nothing major. The circular gray band on the rear of the drum was not a layer of dust, but some kind of air sock/band to stop air leaking from the connection from the drum to the frame. This was not in great condition, but it seemed to be doingit's job still.

Getting the back off was also a bit of work. Most of the screws came out fine. Luckily I had a good fitting phillips. If I had used an incorrect one, which often happens, I would have shredded them. Most were fine but the ones at the bottom were rusted. But, with a bit of WD40 and some gentle back and forth....I got them all off.



Apart from the rust, which is not great. That is all the dust from the last 30 years.....

A quick vacuum and....



In this machine, the chassis is designed to be airtight, as apart from the back panel (which screws on super tight to form a seal), there are no panels anywhere else for air to leak through.

In this instance the fan sucks air in through a vent and pushes it through the front of the drum through a circular sieve. The heating element is in a circle around the front of the drum. I also managed to see part of the heating element, and it looked completely free of dust.The air passes through this and out the back. The filter is at the back of the drum.



It basically does the reverse of the Miele. The Miele's heating elements are before the fan. So the fan in the Miele sucks the warm air the opposite way.

I suspect that this is for ease of use. The Miele's dust filter is on the door, so easier to reach (rather than reaching to the back of the drum). It also has multiple vent points rather than a single extraction point out the back of the drum. But, this in turn leads to all the pipework inside the Miele.

So, what the Miele gains in convenience, it seems to loose in function. Lots more dust to get clogged in pipework and passage ways that are hard to clean without a full tear-down.

This old machine took 5mins, the lint filter is at the back of the drum, and any lint that makes it past the filter, does not get stuck in inaccessible pipework.

There was also no damage to the rather robust seals on the old hoover.....

So, weirdly, I have a sneaky appreciation of the simplicity of the Hoover....less to go wrong, easier to clean.....less dust infiltration...less parts to require maintenance or repair....

 

[dishman]

Step 19: (sorry it's been a while, I just never got round to the final two steps)

Yes, I have finally got around to finishing the dryer!

So, to recap...all I had to do to finish off the overhaul is install the new carbon brushes which form the "auto-sense" system.

As you can see from the previous images the old ones were badly worn and even the armature they attach to was a bit worse for wear.

So first, old and new carbon brushes....a comparison....



As you can see, oddly, the new ones are a bit thicker. The copper wire is also thicker, so they seem better quality. I'm pretty sure I got the right part number for this machine. Maybe they just updated them...



With all the parts, I reassembled the armature that holds the carbon brushes.

However, there was a problem.....because each carbon brush was about 1mm thicker, it was a really tight fit. The foam washers were compressed so much that the carbon brushes had no movement in them.

This is important when smoothly making contact with a rotating drum.

So, with a razor blade, I carefully cut each washer in half. This gave back the 2mm worth of space needed to fit the new brushes whiles having them being able to move freely.

You may also notice that some of the parts had damage.

The first one seems to have worn away it's nubs which snap into the armature. Without these being rounded, it would not stay in.




This part has been rubbing against the drum as it the brushes wore down so low....

New parts? I think not!

Using my trusty friend Milliput epoxy filler....I repaired the parts.



With all the parts repaired, it was then re-assembled.

 

[dishman]

Step 20:

It was then a simple case of re-connecting everything...

First it was snapped back into the armature





I then used stripped back the existing wires and used some crimps and joined them to the new copper thread.
I made sure I made some indentations into the crimps to ensure they gripped.
The weight block was then placed on top and clipped on. This ensures constant contact with the drum and also keeps the wires tucked away.


As you can see, the carbon brushes are making good contact with the drum and there is good clearence beneath them.

When I removed the armature, I disconnected the sensor connection from the PCB. I did not need to do this, but I nearly forgot to re-connect it.



Step 21: - Final Step...

The Final Step was to replace the bulb!

It was a standard 15w incandescent bulb originally. It put out about 90lm so it was not very bright nor was the light very good quality (2600k warm white).

I replaced with a 2.3w (20w equivalent or 200lm) daylight (6500k) Osram bulb. This colour should be more appropriate for seeing clothing colours.
It was also a lot brighter.

My only concern will be how it reacts to the heat generated by the dryer. But, I doubt it will be an issue.

The directional nature of the bulb meant that more light shone down onto the doorway rather than through the window into the dryer.
But, it was so bright it was more than enough!



After that, the lid was put back the rear latches reattached and the side screws and caps re-inserted.

Finished!

 

[60milesmile]

Just a note to the author to say thanks so much for taking the time to do this excellent thread - its really helped me.