Bosch fine adjust - drying targets

[henene4]

Position 0527 is the NTC that's mounted to the refrigeration circuit and not the process air stream.
That just sense the coolant temperature.

As far as I understand, that location allowed to infer the process air temperature pretty accurately and to monitor the circuit for safety reasons without having multiple NTCs.

The other would be located in the front bulkhead in the filter area.

The service literature says that only HP dryers with a refresher system ("Steam") have that second NTC, but I have seen pretty recent parts diagrams for dryers without that still having the second NTC.

BSHs service literature can be quite a wish wash of semi-correct information...

 

[henene4]

Position 0527 is the NTC that's mounted to the refrigeration circuit and not the process air stream.
That just sense the coolant temperature.

As far as I understand, that location allowed to infer the process air temperature pretty accurately and to monitor the circuit for safety reasons without having multiple NTCs.

The other would be located in the front bulkhead in the filter area.

The service literature says that only HP dryers with a refresher system ("Steam") have that second NTC, but I have seen pretty recent parts diagrams for dryers without that still having the second NTC.

BSHs service literature can be quite a wish wash of semi-correct information...

 

[henene4]

For fun I checked my dryers temps today.

I ran a single, big, heavy mattress cover through a extra dry cottons cycle on the speed setting.
Thet cycle was just about an hour and used 0.8kWh.

The exhaust temperature climbed to just above 55C.
Interestingly, it did cycle the cooling fan on that cycle.
Checking the temperature of the duct on the back, it cycled the fan on when that temp registered about 60C and off at 55C.
That points at target intake air temps of 70-75C on the speed setting.

My dryer has (at least) 3 NTCs - 2 on the compressor circuit and 1 in the filter area.

 

[wholelottared]

a question to henene4

Hi henene!! Glad we have informed people with access to service documents like you on the forum.

I saw that you said if we tell the device model, you can give us information about it such as the temperatures, how the programs behaves and how the fan works, etc. I really wonder about these all.
I also wonder how the additional pump that washes the second condenser in the back (which is special to AutoClean models) works, does it automatically work at the end of every cycle or do we have to start the cleaning program, etc.

My model is WTX87EH0TR (in Germany it's WTX87E40 / WTX87E90) basically the Home Professional dryer that's being sold right now.

I would be really happy if you can check about this model and tell me about any interesting thing you found, thank you so much.

 

[henene4]

I can actually tell you the self clean story from memory.

There are 3 self clean systems - the basic self clean system for most dryers.
Then there are the 2 upper line SC systems. Those have the condenser cleaning. (Condenser as in the technical term, meaning the "hot" heat exchanger. Refrigerant condenses there, releasing heat.)
The 3rd tier is the full AutoClean system which has no main fluff filter, only the trap in the bottom you have to clean every now and then.
So - technically - you can have condenser cleaning without the full AutoClean system, but I don't know of any model implementing that.

The 2 systems that also flush the condenser don't use a second pump.
They use a thermal actuator that just diverts the flow from the first path which just flushes the evaporator to the secondary path to the condenser.

The condenser rinsing is triggered based on total operating time - I think every couple dozen hours.

More interesting is actually the alarm for cleaning the lint collector on the AutoClean models.
It uses several mechanisms to check for how full the trap is.
First is if a certain total operation time has passed. Second is if a certain number of cycles have run. Third is if after flushing the lint collector, it takes to long for the water level in the water collection area to rise. The thicker the fluff layer, the longer it takes for the water to get through it.

And it goes even further than that. Apparently, during testing, the concern arose that customers don't like to handle soaking wet fluff.
Thus, if the dryer senses the need for the trap to be cleaned, it actually waits for the next cycle to complete and does not run a rinsing stage during that cycle.
That leaves the fluff much dryer, making removing it easier.

I'll check the rest tomorrow when I'm back at work.

 

[wholelottared]

thank you henene4, can't wait for additional info

Wow thank you for the info!!

It always makes me happy to hear interesting inside info and facts from you, it's so cool. Can't wait to hear the details you'll share tomorrow.

Btw, from what I know, all the Self Cleaning Condenser devices washes the first condenser, yes, but only the AutoClean devices washes the both condensers, the one in the front and on the back.

I saw a Russian video in YouTube and someone was inspecting the insides of an AutoClean model, and they were actually showing the additional piece that washes the second condenser in the back. How does it divert the water to that part? That's what I was wondering.

Here's the link to the video i'm talking about, you can see it on 0:36 :

Will be waiting for the other infos you'll share about my model, thanks!!

 

[wholelottared]

addition to my last reply

and oh also, there's something i really wonder a lot. during the AutoCleaning phase, right after it flushed the condenser, sometimes the drum stops and wait for like 2-3 minutes until it continues. sometimes this doesn't happen and the drum continues to spin right after flushing. why does it happen? what determines the drum stopping for like 2-3 minutes or continuing right away? this part behaves differently literally anytime i run the machine (sometimes the drum stops sometimes it doesn't) so i think maybe it has something to do with the temperature? maybe it stops the drum when the clothes are too hot, so it can be like a cool down? idk. let me know if you know anything about this please. if you can't understand what i'm talking about, i can take & share a video.

 

[logixx]

Judging by the parts diagram, the condensate pump is connected to a diverter that switches from pumping the water up into the tank, to pumping the water through this short hose onto the condenser.

 

[henene4]

Some corrections

So actually, yes, the main pump is used for flushing.
The diverter I had in mind is situated in the drain pump, makeing a total of 2 thermal actuators down there max.

The SC2 system has automatic filter flushing but NOT condenser flushing, so I switched that up.

 

[henene4]

Unfortunately, both your dryers have revised cycle charts that do not list target temps.

The 2 examples are both A+++ dryers, one with Inverter one without.

The compression on here isn't doing it any favours, but should be doable if you zoom in enough.

 

[henene4]

Actually, Logixx, going to through stuff, you dryer has actually an old cycle chart available and lists 65C NTC temp as limit.
You dryer should be KI-index 12, so WTWH7540/12.

On all other dryers, there's a testing document for end-of-line and service testing that shows power consumption depending on temperature.

 

[wholelottared]

replying to henene4

wow, these were all so interesting to read, i'm shocked by the amount of interesting and detailed info. thank you so much.

but i'm confused by two things. sorry for asking you a lot.

firstly, the way it washes condenser in the back is way more complex than i thought. it says it only washes it every 75 operating hours, and on standard programs. what do they mean by standard programs on that, which ones are standard? for example 90% of the time i use the program i saved on “memory 1” which is synthetics cupboard dry extra with +2 drying target and low temperature. would this be considered as a standard program? i hope it does haha. at one part it talks about how programs behave and their features, maybe they wrote about that there, i would be really happy if you can check if the program i talked about flushes both condenser and the evaporator. is there any indicators to understand while it's cleaning both condenser and evaporator? like would i hear a sound or does the selfcleaning part gets longer?

and secondly, can you please check if the “care programs” which is used to manually start the flushing programs include the both condenser and evaporator washing? there are two care programs, i wonder if they both do it.

thank you again. btw some of the pictures were so hard to read, and i didn't understand most of the temperature target things. for example is synthetics cupboard extra targeting for less heat compared to cottons and mix? are a+++ devices running less hot than a++ devices?

idk if that's possible for you, but i would love to read this whole document/pdf so much for my AutoClean model. i promise to not share it anywhere, it's just for my interest, and for since i'm too eager to learn about these all. i can give you my email if you can send it to me, i would appreciate it sooo much.

let me know about these please, thank you and have a good day

 

[henene4]

Can't share that on here anyway.

The targeted temps for fan cycling are - for those models that display them - the same, regardless of cycle with very few exceptions.
Delicate fan cycling temps are somewhat lower by a couple of degrees.

As far as I understand "standard program" means just any regular program, just not timed cycles or very short ones.

The care cycles aren't described any closer, but they mention that the message to run them is displayed either after 300h or if 10 of the condenser flushing cycles have been skipped (due to special cycles or to little water).
That indicates that they both do run condenser and evaporator flushing cycles.

 

[wholelottared]

Thank you henene4. Do you think this is better than LG?

Do you think this complex AutoClean system clean itselfs better than LG's Self Cleaning dryers? Do you know how those work too? Thank you.

 

[logixx]

Correct, mine is a WTWH7540/12. When idle, the temperature readout through the service menu says 23C (and also 30C, which presumably is that dummy value). It also shows Lo and 253 when consecutively pressing the four buttons above the display left to right. I'll see if that 23C value changes the next time I dry a load.

Thanks for the screenshots. Super interesting.

 

[henene4]

LG SelfClean

It's simpler in certain ways and more complicated than others.

Not better or worse per se, though their inverter heat pump is way more flexible than the BSH ones from what I experienced.

 

[wholelottared]

an another question to henene4

Home Professional dryers has an additional fan that's right back at the TFT screen.

I know this is probably there to the block the possible condensation reaching the screen, but is there any explanations of the fan on the service documents you posted? Why the Home Professional washing machines don't have it, but the dryers do, even though washing machines generally create more steam/condensation?

I would love to read about it, thank you so much!!

 

[henene4]

Dryers most definitely create more condensation for sure.

Let's say you have an 8kg load spun at 1400rpm.
At 50% residual moisture, that's 4kg of water.
Now run that through even an A condensing class dryer, about 10% make it out if the dryer.
That's 400g of water - that's like 2 normal size drinking glasses.

Your washer does not aim to evaporate water, your dryer does.

 

[logixx]

I think there was also a fan for the inverter board. Kenan763 has a video showing it, which I linked previously.

Been running two Extra Dry cycles this week. Initially, the timer adds 16 minutes when going from Normal to Extra. However, it actually added 22 minutes for the extra drying. On both cycles with different loads. Conclusion: set and forget and only return to the dryer once it's done. No use in making sense of the thing. Clothes come out dry, that's good enough.

 

[mrlaundry1011]

So…. My sister has now taken my Bosch to use instead of using the washer dryer to dry. But the last 2 loads, it hasn’t dried properly (total mix load), thinner items coming out dry (as you’d expect) but the more cotton items still quite damp (50/50 split loads). I’d expect it to do this if only 1 or 2 items were cotton but not this amount. It’s annoying as if you seperate, it cannot sense the fleecy type fabrics at all and stops immediately, forcing you to use time dry. This is using the saved programme which I saved Mixed fabrics with cupboard dry +3. Now I’m thinking if it would be better to save cotton cupboard plus +3? Doubt there is any temp difference between cotton and mix.