Thread Number: 78318  /  Tag: Modern Dryers
Bosch Heat Pump Drier
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Post# 1023444   2/2/2019 at 22:14 by spinspeed (Far North New South Wales Australia (originally London UK))        

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So, had to buy a new drier as was not able to get my Maytag drier connected up to a 30 amp outlet. We are now living in rural Australia and have a crappy Power supply to our house. So brought a Bosch series 6 heat pump drier. Have to say am pretty impressed with it. Did a load of towels spun at 1400 and did a great job in just under 2 hours. Was expecting longer cycles as much Lower temps in heat pump drier but significantly cheaper to run. Bit disappointed does not reverse tumble which I thought would be standard these days. Reading on line the heat pumps donít really get a good report but I am happy so far with mine. Takes 9kg load which isnít bad. Not as impressive as the old Maytag but a fraction of the running cost I am sure.

I hate line drying in Australia, the sun is so harsh and especially towels end up like cardboard. I think I will use my new drier rather than hanging out. Hopefully the initial bigger outlay in cost will pay for it self in power savings. Also we have solar power so may even be free to run.

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Post# 1023452 , Reply# 1   2/2/2019 at 23:55 by henene4 (Germany)        

Given the lowest efficency dryer in Australia from Bosch listed on their website (which looks like yours) that would be an A+ efficency class dryer over here.
If you post a model number or an excerpt from your users manual usage tabel (full load cupoard dry from 1000rpm) I can pinpoint which heatpump you have exactly in your machine.

A+ is "old school" by now.
Currently, all dryers from A+ to A+++ take about the same time for a standard load over here (betweeen 150min and 180min per full load cycle from 1000rpm).
Most have simmilar one speed heatpumps (meaning 1 single drying heat basicly).
Only few dryers have an inverter multiple speed heatpump now, and those are usually A+++ -10% efficency class.
Only difference is how much wattage they pull. That is about 800W, 7000W and 550W for each efficency class respectivley (in general, Bosch is an exclusion there).
Inverter heatpumps vary in wattage throughout the cycle thus less predictable.
So, with your machine, you can estimate the usage per cycle pretty easily: Check your manual for the usage per cycle. Divide that by the numbers of hours and you got the usage per hour approximetly.
Bosch has the most diverse setup of heatpump bases, so a model number is really needed for that.
But a general rule of thumb is less then 1kW per hour of use for sure, thus less then about 1/5 the usage of an US dryer or less then 1/2 of an EU sized vented or condenser dryer.

Trick here is not that you dry in hot air but you dry in dry warm air.
The heat generated is on one side by the removal of mass out of the load while the energy contained in the load is about constant, plus a lot of waste heat from the heatpump goes back into the drying circuit.
A heatpump can move about 3 to 4 times the power it consumes in electrical energy in thermal energy.
So a 500W heatpump drys about as powerfull as a 2kW normal dryer.

Imagine a 500W air conditioning unit in a room not even big enough to stand in (about 250l in volume max) except all the waste heat goes back into the room.
The air is insanely dry but only heats "moderatley".
As the cycle progresses, more heat means faster drying.
For example, for a cupboard dry plus cycle, our A+++ dryer predicts 2h 39min for a full load. For that, from iron dry to end the time calculated is only about 41min though the residual moisture is still about half.
Means low temp but good drying.

Now the main issue people have with those dryers is 3 fold.

First, they don't understand the drying system.
They check the load after an hour and it is barely warm, then they stop the cycle every 5min.
Some heatpumps have a safety switch that delays the restart 1 to 5 min after the cycle has been interupted to protect the heatpump. In that time, no drying progress is made.
Colder laundry feels damper, thus drying progress is often judged worse then it actually is.

Second, the machines "cupboard dry" settings are geared more towards efficency, that's why many machines have dry adjustments or more drying degrees.
Cupboard dry + is more like the cupboard dry of yesteryear.

Third, the lower temperature drying in dryer air changes drying results fundamentaly.
A vented dryer produces bone dry laundry that has many characteristics simmilar to air dried laundry, less fluffy then a condenser, but dry and warm and fresh.
A condenser dryer produces "steam treated" like barely wrinkeld incredibly fluffy laundry, but softner is barely noticeable.
A heatpump unit lacks the "air dry" freshness and "steam treated" feeling, but ANY smell on the load left after the wash still remains after drying and the load has a "dehydrated" feel to it if you know what I mean. Laundry is basicly hand warm thus danp seams don't air out and dry and feel damper, but if it is 100% dry, it akmost feels overdried, though you can basicly dry any cotton fabric no matter wgat whithout any damage.

Bosch (BSH for that matter) were the first compatibly priced heatpump dryers back in the day.
Most people dried only a part of their laundry in a dryer, so pre "blueTherm" (Siemens) or EcoLogic (something like that on a Bosch) heatpump dryers made sense only wheb you dried tons of launrdry.
AEG (ELux) had heatpump units in the mid to late 90s. They were about twice as expensive, safed only about 40% over normal dryers and took about as long as todays dryers.
They used a seperate fan and drum motor allowing for full drying power independent of drum direction and a quite large heatpump and low efficency air flow design.
Miele copied that design for their first gen HP (heatpump) dryers and uses that for their professional heatpump dryers to this day.
Then BSH changed the game with the first 1 motor high efficency airflow design machines. That made them cheaper (only about 50% more expensive), easier to care for (SelfClean condenser) and more efficent (about 20% more efficent then the first ELux units), but ditched reversing for that due to their blower design (reversing would have ment so low air flow that the cold side of the heatpump could freeze over, and turning it of wasn't viable due to the 3min restart time on average) and that self cleaninf often enden up as a service call after 3 or ao years.
Next efficency boost was more effident motors and inverter heatpumps, saving another 10% or so and occupying the high end sector. You will hear your machine start out quiet and getting louder as the cycle progresses. The louder the less efficent it runs. An inverter tapers down heatpump power as cycle progresses.
Then reversing got possible again as heatpumps almost halfed in power and increased in airflow.
The we switched to the new energy label up to A+++ and one speed heatpumps allowed for the top rating after one generation.
These dryers of current gen can dry 8kg of laundry from 1000rpm in about 2,5h with only 1,4kWh of usage at max temps below 55C for as cheap as 500Ä.

Fun fact there: There were only 3 exceptions of dryer design philosophies that drasticly diviated from the current state of art which basicly mostly consistently took about 2-3h to dry a standard load with some reversing.
The cheap dryers took 4h or longer with worse specs overall getting only more efficent by venting lots of humidity into the room.
Mieles first gen HP units ran insanely fast (90min or less usual) with perfect 50:50 reversing with (at that time) average usage mostly due their high power seperate fan motor that allowed for a high power heatpump unit. They made an A+++ design of that before changing from that "TwinPower" branded design to the one motor T1 design base.
Bosch scratched fikters and reversing in the early 2000s. All was well and fine for about 2 years. People complained if tangeling of big loads, so they added tgat cone in the back. Then the SelfCleaning kept failing out of warranty. So they first added the stacked 2 stage filter, then they added seals to that and finally moved the issue part (the condensate pump and related level sensor) to the back of the machine so taking care of that wasn't a 300+Ä service call any more for taking apart everything basicly and turned that into a 150Ä 15min service call and they added low efficency models with manual clean filters afterwards. They never readded reversing though they still tangled like hell. To this day no BSH made dryer reverses, period. Though they added that under the "features" tab on the german websites, it is crossed out everywhere. For AU, that is under "technical specifications" -> comfort. Crossed out for every model as well.

Tips from a user of many such machines:
1) Use a cupboard dry setting with an increased dry level for basicly everything.
2) Always dry items that dry about equally quickly (T-Shirts, underwear and socks n such in one load, jeans in another, towels in another) together.
3) If you dry a single large item or bedding loads and they tend to tangke, get used to it. Either start with a cupboard dry setting and dtangle at thend, set to a sgort timed cycle and repeat until everything is dry or start with timed straight away.
4) If you like the machine after a year of use, reduce the usage of fabric softner, read up on how to clean the condenser and drain pump yourself. Pretty easy, an 1h job or so after the first time.
5) If you don't like it after a year, sell it with a year of warranty left as barely used and buy a reversing machine (anything Arcrelik made should tangle verry little, but even better would be a machine with a bedding cycle like AEG (ELux is the same), Gorenje or since verry shortly ago Miele)).


They are completly different beast of dryers.

The more efficent, the genteler and quieter. Basicly everything can be deied in them as long as all items are about equally thick.

Towels are a good comparison load; basicly everything today dries them equally well.

Large items are an issue due to tangeling; if you get annoyed by that, sell your unit with some warranty left as barely used and buy something with a reverse system and a bedding cycle.

If you have questions, just ask :)

Post# 1023453 , Reply# 2   2/3/2019 at 00:12 by richnz (New Zealand)        
Oh how could you not

love a hard scratchy towel?

Experiment with 10 minutes of dryer and then finish on the line.

I love the cost of drying of the sun. Also the disinfecting and whitening factor that you get too.

Here across the ditch in NZ the sun irradiates.

Post# 1024079 , Reply# 3   2/9/2019 at 06:46 by iej (Ireland)        

I have a Miele T1 heat pump and to be quite honest it's a fantastic machine. It dries very well. It's not particularly slow and has excellent non-gimmicky approach to things.

They keep the fluff out of the heat exchanger using a very fine mesh filter a bit like what you'd expect in a vacuum cleaner. This is just washed out once in a while with warm running water. It's not a big deal. Then you've a double layer of filters under the door which are just the same as normal dryer filters only a bit more accurately designed.

All in all - can't fault the machine. Great results, no shrinkage, very gentle, handles big loads of towels no problem at all. Reverses.

The Miele scent pods are didn't appeal to me at all though. Very overpowering and unnecessary.

Post# 1024089 , Reply# 4   2/9/2019 at 09:20 by foraloysius (Leeuwarden, the Netherlands)        

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I have a Siemens IQ 500 heat pump dryer. Model number is WT7U4691NL. It's has an A++ efficiency label. The only downside is that it doesn't reverse, but bed linens don't tangle up very often. I hang up duvet covers after 30 minutes in the dryer anyway, have always done that with every dryer.

I believe this is the second design, there were some problems IIRC with the self cleaning system. This system works great, the second picture shows the inside that is kept clean by rinsing it with the condensed water. Hadn't opened it in several months and didn't wipe it before taking the picture.

The Siemens has a double filter too. Drying times are always shorter that initially shown. And it is very flexible in it's settings, you can select all sorts of drying levels.

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Post# 1024100 , Reply# 5   2/9/2019 at 12:38 by iej (Ireland)        

I think there were issues with the self cleaning system on earlier versions of that machine.

Miele's approach also seems to work extremely well by just using very dense filtering.

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