A question to BSH dryer enthusiasts, especially to henene4 since he's really knowledgeable

[wholelottared]

I have a question i'm wondering about modern Bosch / Siemens dryers. As y'all know, new Series 8 dryers with the new design can reverse on the bedlinen cycle during the whole program. Here's an example video of them reversing:


So my question is, does this device has any new motors or anything different compared to already existing Home Professional dryers for example which is still sold?

If you want to check and compare, here's everything inside the new Series 8 dryer: https://www.bosch-home.com/us/supportdetail/product/WQB245B40/01#/Tabs=section-spareparts/

And here's everything inside the Home Professional dryer: https://www.bosch-home.com/us/supportdetail/product/WTX87E40/05#/Tabs=section-spareparts/

So my question is, if every motor inside them is the same and if the newer devices doesn't have something new to be able to reverse (which i think is the case, but i can't be sure), can Bosch bring the reverse feature to already existing high end devices like Home Professional via a software update? I'm almost sure they wouldn't do that since I think firmware updates on these things are a lie and they never do that, but still wanted to ask.

I wish we can contact BSH and request this as a software update.

If the links doesn't embed, you can copy and paste it to your browser by the way.

Will wait for the answers I wonder what y'all think, thanks.

 

[logixx]

I did a comparison between the new and "old" models some time ago. I seem to recall that there are some differences like the fan, for example. Not totally sure right now.

I doubt BSH would make such a feature available via a free software update, even if there's no new "hardware" needed. Miele offered an upgrade to, I think, 1800 rpm on select washers for a while. Essentially a technician came to your house, simply changed the max spin speed in the software... and charged you for it. Bu who knows. Maybe. Another YouTuber had his dishwasher updated and had two more cycles on it - accessible via the app. My dryer got an update, although I have no idea what it was supposed to change. They could have added the two self-cleaning "care" cycle, for example. Would have made sense, I think.

 

[henene4]

There is one fundamental difference

First off, some airflow parts are different. The process air fan (that moves the air through the drum) is different.
Though that isn't the issue.

The big difference is that there is actually no physical way to make any BSH dryers that aren't reversing from the factory to reverse tumble without hardware AND software changes.

The models with induction motors (capacitor, no inverter) don't have the reversing relays on the control board.

On inverter models, explaining why that still isn't possible is a bit complicated.
An inverter could just change the order the fields run in, right?

Well yes, it technically could.
But for that, an inverter would have to be build to do that AND would be abled to be told by a control when to reverse.

The inverters on all BSH dryers that do not reverse are NOT build to reverse, not even to run at different speeds.
To the point that there are 3 different inverter parts for the 3 different motor speeds that are needed across different efficiency and load size versions of all the dryers. They use an inverter that does not even have variable speed functions.

On the machines that do reverse, entirely different motor inverters are used.
Besides now being abled to tumble in both directions (still, only one speed from what I gather), the big difference is that they ARE connected to the communication bus the control uses to tell different parts of the machine (for example the additional components on steam dryers).
Only that communication connection even makes it possible to tell the inverter to do anything specific.

The reason why such a system of one central and many small controllers talking via a bus is even used is the plug and play nature of it.

That makes adding for example iDos to a washer, or steam to a dryer, much simpler.
You just hook up that new item to power and the communication bus, and there you go.
No new specific electronic control needed.

That was a move that was made mid platform on almost all BSH appliances when WiFi enabling all appliances became a goal.
BSH introduced something called the "System Master Module". That managed all the connectivity AND many functions of machine control - cause connected features often needed to control to start a cycle for example.
The SMM does NOT do specific tasks, like start a motor, activate a relay etc.
However, it IS hooked up to the same communication system that is used to talk between all controller parts - that way, it can update all of them and check status for faults etc.

Because the inverter for dryer motors was originally designed to be a drop in replacement for the normal induction motors, there was never more designed into it than "run when power is applied".
Thus they were never really talking to the control.
Thus they were never migrated into that communication system.
Thus they still don't talk to the control system.

Of course unless you have a machine that can reverse from the factory - because than of course it talks on the communication bus.

That's why I was so taken back when I got access to the service data base for the first time and read the documentation.
The only reason BSH dryers ever had an inverter motor until a year back was efficiency and noise.

They had the opportunity to add reversing years back, and it would have been very easy.
But they specifically didn't - the inverter in the HomeProfessional dryers is one of the most overbuilt solutions that could do SO much more than it is used for, if anybody ever cared to give it the possibility.

 

[henene4]

@alex

I think the reason your dryer did NOT get the self clean care cycles is that those are only available on newer revisions of the self clean system.

There is a plethora of different versions of the system, with many solutions botched in and out over the decade and a half it has been in use.

Essentially, from what I gathered, when designing the AutoClean models, they unified all versions of the SC system - even those with no SC (SC0) to use the same unified machine base.
No matter if you get the entry level EasyClean or the TOL AutoClean, the plastic housing for motor, compressor, heat exchanger etc. that's called the machine base is the same - as long as your model has been released after the AutoClean redo.

If I ain't mistaken, you have a model that has been on the market before that point.

 

[wholelottared]

Replying to henene4

Thank you so much for your detailed reply, it's sad that they will never get the reverse then. But I kinda expected this result.

But by the way, AutoClean ones has a really big difference so it's not totally the same base. They have a different water motor and additional pipes to wash the unreachable condenser at the back too, not only the front. They're the ONLY driers existing in the market right now that washes both the front and the back condenser.

You can also see it from the links I posted above, the parts 0576, 0574 and etc on Home Professional are used to wash the back condenser that's normally unreachable. Hope what i'm saying is understandable.

 

[wholelottared]

Forgot to add, adding to my last reply

That back condenser washing system doesn't exist on even newer Series 8's so it's special to AutoClean devices for some reason. They probably added this because there's more chance that dust can go there with this system, so they added a more detailed and perfect cleaning system that washes both condensers instead of just one.

 

[henene4]

The hardware on it is different yes.
The base itself, the plastic chassis, is the same across the board.

 

[mielerod69]

Reverse tumbling

I just recently had my 13-year-old Miele T8929WP dryer serviced as the cooling fan for the refrigerant failed behind the grill on the right-hand side vent.
This caused the compressor to overheat and cut out, therefore not being able to dry the laundry effectively. The tech came and replaced it. It took two hours to do.
I will keep this dryer running as long as possible because it has true reverse tumbling. These series were called TwinPower as they had one motor for the fan and one motor to drive the drum. This allows you to dry with the drum stationary like in the basket program, or pause the tumbling periodically when the gentle tumble option is selected. Never a problem with balling of bedlinen.

 

[henene4]

@mielerod69

Since you live in Australia, Fisher and Paykels TOL dryer has a separate drum and fan motor aswell.
Mieles Professional HP dryers all have a TwinPower design too.

It is the best design for drying, yes, main reason it was abandoned was cost and efficiency.
There are pretty good heat pump dryers for reversing by now as well - but nothing beats the seperate motors.

Though to note: That's not a Miele invention. The first heat pump dryers were AEG built (not sure if pre or post ELux acquisition, must have been in that time frame) and used a pretty similar setup of drum and fan motor seperate right up until the first Protex dryers.
AEG/ELux always reversed often and regularly - their bedding cycle was always pretty good regardless of what design it was on.

 

[logixx]

Henrik

My dryer is a WTW7540 from December 2019. I don't mind not having the cleaning cycle, as I can run it manually under the P:03 setting with as many flushes and soaks as I like - although I'm trying to keep the dryer super clean anyway.

What I find interesting is that my energy label states that the dryer takes 148 minutes for a full load. Dryers with the same values (capacity and efficiency) but different filtration systems seems to take longer? A current EasyClean dryer takes 165 minutes, while an AutoClean one takes 195 minutes. Does the filtration make the difference?

 

[henene4]

The WTWH7540 is listed since 2017 on the idealo web page, so it is based on an older version of the architecture.

BSH praised themselves for a long time as the fastest A+++ dryer on the market - and they were.
But I think the main timing difference isn't in the filtration.
I don't think we design any dryers as fast anymore - biggest difference I guess is the type of refrigerant used (most of the dryers today transitioned from R134a to R290).

Then comes noise. There are 3 different inverter speeds used depending on model and those directly correlate to fan speed.
Lower fan speed means less noise - but also probably longer drying times.
I think most if not all easy clean dryers still use normal induction motors with capacitor?
The fast dryers were pretty quiet, too, though, but the quietest dryers were pretty slow. So maybe the fast dryers run higher fan speeds but better insulation?

The AutoClean dryers do run more and different flushing sequences, but those don't account for 30min difference.
They do have different evaporator/condenser designs which will influence how fast you can dry.

The function correlating efficiency and drying speed is a bit convoluted.

You want to gather as much condensation energy with as little compressor power as possible.
That doesn't mean you want an as low power compressor as feasible - you want as little compressor power as possible per unit area of heat exchanger while reaching the same temp of air after the evaporator as that roughly governs how much water you condensed out.

So, if you can manage huge airflow with reasonable power on the fan side over a heat exchanger that is equally huge, you can get wicked fast drying at high efficiency.
Miele Little Giant T1s manage A++ for 8kg - in less than 90min while still saying you can dry all items regardless of 1 or 2 dors in the dryer symbol at the same time.
Their full size professional HP dryers manage to dry 12+kg of laundry at A-level efficiencies in under 40min.

On the same hand, the refrigerant used plays a role in how you can design your dryer to reach certain efficiencies.
R290 can be just as efficient as R134a - it just probably moves less heat per unit mass, while probably running lower compression ratios, thus needing less energy per compression cycle. That means it just takes longer to move the same amount of energy with the same efficiency.

But I will have more insight on that after my bachelor's thesis as part of it will be comparing different refrigerants.