Dishwasher Pre-Wash Cycle

[washer111]

Hi Guys,

I'm new here, and I joined so I could join in with discussions about vintage washers etc. We don't own any (and probably won't), but I think the Unimatics of the 50's and the GE Top-loading electric sinks are also pretty nice dishwashers.

What I've come to ask about today is the Pre-wash cycle on dishwashers. What are they used for?
I've got the impression they have something to do with having the dishwasher connected to hot water, and the need to have it in the pipe ready for the machine to go into main wash. Am I right?

The thing is, practically no dishwasher here in Australia has the cycle.
The neighbour's house has an old Asko/ASEA 1302 from 1992, which has prewash, main wash, 2 rinses and a 10 minute dry and due to hard water, the repairman said there isn't any point having it in service - since it broke down a lot due to water conditions. See the photo attached! Since the people who own the house don't own it anymore, I can't fix this machine - although I wanted to before we got the dish drawer, and use it as our own machine! (These are supposed to be very reliable - but use 8.5 Gallons/32Litres of water!)

Our 2011 F&P DishDrawer DD60DCX6 has a Pre-wash detergent compartment, but it isn't used - even running the "rinse" cycle (12 minutes, stated in manual as the actual prewash) doesn't use this compartment. However, detergent in there is used during the rinse cycle I believe (hence the warning in the manual not to use it).

I also knew someone with a "Vulcan" (became Dishlex in the 90s) machine from the 70's. According to the owner, connected to hot water! No detergent dispenser either... The machine kicked the bucket last year, but had new hinges from an NOS warehouse in 2009, when we lived nearby. We had a 2007 Dishlex 203 - no prewash there and connected to cold water (it took tablets well even on the 30min Cold cycle!). One of the last locally made ones too (July 07, before they went China. Looking at the appliance store today, they feel cheaper).

 

[dj-gabriele]

Gosh, what a limescale deposit! You really need a machine with a built-in water softener!

Pre-wash, at least in my opinion is useful if one uses a low temperature cycle or doesn't run the machine right away: when using the time delay function in current SMEG machine a pre-wash is automatically run and the water saved for when the machine starts, doing this has two benefit, the first is that it wets the dishes and keeps the dirt fresh, the second is that it lowers the odour that could form in the machine (that's an exclusive feature of them)
That's what I manually do with my machine for the same purpose as sometimes I don't completely fill the machine when I'm home alone.
Purging the water line is something that was never used in Europe as all the machines are self-heating, even those connected to hot water (most modern dishwasher can), so the pre-wash in this contest is not necessary.
Also one is supposed to not use powders in the pre-wash even if some machines have an indentation on the dispenser to put the detergent for the pre-wash is the dishes are particularly dirty but it's not a real dispenser, just an indentation.

 

[washer111]

Limescale is not my fault! Our house has a water softener, so the DishDrawer is very happy

25 grains hardness here...

 

[volsboy1]

 He wasn't being rude or mean or anything by saying that about your dishwasher.I have terrible hard water also and mine or anybodies do that steel shows the worst  of it. I use Citric Acid dishwasher cleaner you can buy them at any grocery store, and your machine will sparkle on the inside like new and run better because that is also inside the arms and can restrict your cleaning.The cleaner is a bottle you just plop in there and run while empty on the longest cycle.They have a wax plug that will melt away.I use Dishwasher Magic or Finnish Dishwasher cleaner but I don't have much problems with build up cause I have a lot a phosphates in my detergent but it also cleans grease out of your arms and pumps.

 

[jerrod6]

I have a DW from 1996.  Most of the cycles have a prewash.  My take on it is that it is used to knock out the big easily removable soil before the machine goes into the main wash in which it will heat the water.  Mine has a small prewash detergent cup so you can put a bit of detergent in there if you want to.  During this 13 minute prewash the DW checks the soil level in the water and if it finds light soil it will not do a water change for the wash  it just opens the main wash cup and starts the main wash. Moderate to heavy soil will cause a water change with a fill of fresh water for the main wash.

 

Most of the cycles that have a prewash have it lasting 13 minutes which includes the fill period.  There is one cycle on the Dw labeled "Normal"  which I don't use because it does two prewashes  a 6 minute followed by a 10 minute rinse and each of the fills in this cycle take more water than other cycles.. which seems like a waste to me.

 

[washer111]

Yeah, that old Asko could use some TLC. Rusted racks (Silicone fixable probably!), Finish D/W cleaner, de-cockroaching (yep, they live in the pump), Sulphuric Aciding (joking!).

The powerpoint is located behind it, and I think it's still on, and the water is in the adjacent cupboard, again still on (probably to stop tap leaking, like ours did initially). It'd be worth a shot to test it, since we have compulsory Earth-leak breakers in this country. The machine doesn't really have anything interesting about it - you can start the machine at Prewash, Mainwash, 2 rinses or the drying cycle for "plate warming."

The Asko/ASEA 1402 had more options in a timer based model, used less water and was probably just better!

In reply to volsboy1, I wasn't being rude, I was just pointing the finger at our water supply! Its ridiculous they don't even attempt to soften the water before delivering to our homes via Asbestos piping (yep, thats how old this place is). At the supermarket, almost every person is buying the big 2.6 Gallon/10Litre locally made bottled water.
The local water softener supplier charges ridiculous amounts for their systems (around or over $1000 for a 24K system). We repaired our vintage one last year, but the control valve failed, so we bought the parts from an softenerparts.com - run by Andrew Cross. A very good service!

 

[washer111]

By the way, here is our dishwasher: 2011 Fisher and Paykel Double DishDrawer DD60DCX6. Note the detergent dispenser is open. On the left, is the prewash compartment and on the right is the main-wash compartment (has the two posts in it). Indeed a very nice wash from this puppy - even before the water softener (thank god for Finish Quantum tablets!) Just drop em' in the bottom.
By the way, there is to be no liquid detergent use with this puppy - too much foam, i think because of the low water usage, so tablets aren't recommended either (except in hard water).

Uses just 1.77 Gallons per wash (2.23L/.59Gal for each water change, only does 1 wash, 2 rinse + 30min dry). Thats top-loading design for you! I wonder where they got the design idea from - Maybe (just maybe) the old GE Top-loading electric sinks of the 40's and 50s (as on youtube.com/dishwashercrazy).

The normal cycle is 114minutes, eco brings it up to 140mins. It washes much colder than conventional machines too. The "normal" cycle is at 55ºC/131ºF, with 60º 2nd rinse! The water pressure also varies between the different cycle options, to pamper china/crystal and scrub those pots! Its quiet too

Enough from me

 

[rapunzel]

Australian machines used to all have prewash and their programming was modeled on US machines. Likewise, Australian branded dishwashers still allow for hot connection, unlike many other imports that are only designed to take cold. I've got my dishdrawer connected to hot water.

The prewash in your F&P drawer only activates during the heavy cycle (the sequence is prewash, rinse, main wash and 2xrinse). You are right, none of the other cycles flush the prewash cup as they go straight into the main wash. As you have a later model than mine I've noticed that your cutlery basket looks much sturdier.

 

[washer111]

Actually, my machine goes straight into a Main-wash in all cycles except rinse!

So I guess in having a later model, it's omitted pre-wash for heavy cycles! I've just read through my manual, and the heavy wash is in fact just main wash, 2x rinse and dry.

And yes, I having seen the older DD601/603 models, this one looks a little better! The older machines also didn't have the angle shelves to the left, something some friends of ours with a newer one hate (since they had a 4-5 year old machine replaced under warranty).
The new ones definitely look far better I say, and the buttons are more durable. Whats the water usage on yours like? Is it the same?

 

[retro-man]

To washer111

Interesting dishwasher drawer. I had never see one of these open before. Looking down into it, is that the floor in the kitchen that you see underneath? Not having one or seeing one before, wouldn't that be messy loading dishes and stuff falling down onto the floor? Or is there a clear covering there to stop things from falling though? Thanks
Jon

 

[rapunzel]

Whats the water usage on yours like?

Don't really know. I think it rated three, perhaps four stars (about 7 liters per drawer on heavy cycle, not sure exactly). I am not too concerned with water consumption in that regard. It sounds like it moves quite a bit of water and washes very well (I don't pre-rinse). If I were to wash by hand I'd use a lot more water.

How long is your regular (not the eco) heavy cycle? Mine starts off showing 130 minutes (including drying), but it is actually 15 to 20 minutes quicker due to hot water fill. I got mine in 2003 or 4, not sure anymore. But it does have the little flip down shelves on both sides in each drawer.

 

[rapunzel]

is there a clear covering there to stop things from falling

retr0-man, the shiny round disk in the center of the drawer is made of stainless steel and what you are seeing is the reflection of washer111's ceiling in it. Noting can fall through the dishdrawer. It is actually better for containing spills than a front opening dishwasher.

 

[dj-gabriele]

Limescale is not my fault! Our house has a water softener...

I wasn't talking about you at all, mine was a generic exclamation, anyway I see what happens when I forget to add salt to the softener, glasses are all sand like and stuff never come clean!

25 grains of hardness? That's quite hard, same as here! Our dishwasher chugs one kg of salt every month!

 

[MrX]

Any dishwasher I've ever had here in Ireland over the years, which have included : Ariston, Hotpoint (rental places), Zanussi, Bosch and Miele have had pre-wash cycles on the more intensive washes or, on the auto-wash if the dishes are dirty enough.

The pre-wash on most European dishwashers is a short, usually cold/cool, cycle which is designed to remove loose dirt. The filter system on most European machines is self-cleaning, so any loose gunk is removed in that prewash and pumped away down the drain.

Tbe machine then continues onto a hot wash cycle.

More modern machines use the prewash as a way of checking how dirty the dishes are. They use a light sensor in the bottom of the machine to check how much light passes through the water, and then, if it's very dirty, they will do a full prewash and then a mainwash. If it's not too dirty, they'll just turn the prewash into a mainwash, heat and continue.

Older machines here were sometimes hot fill too, like the USA, but they always had the option of heating their own water to very high temps.

The older machines cycles (pre 1990s) were something like this:

Short, hot, prewash with detergent.
Long main wash with detergent.
Rinse X 2
Dry with heaters.

Newer machines:
Short, cold/cool prewash (optional) - normally without any detergent.
Long mainwash with detergent.
Rinse X 2
Residual heat drying (some e.g. miele use a fan)

 

[rolls_rapide]

Salt usage

You should go for Bosch, mine uses ONE complete salt fill per YEAR, set on setting 4 or 5 of seven possible settings (0-6). I kid ye not!

Mum's Hotpoint/Indesit uses one salt fill per 6 weeks, set on lowest setting.

Bosch machine is frugal, Hotpoint is a glutton.

 

[launderess]

Took The Plunge Last Night

Set our Frigidaire portable to "Water Miser" setting (flush,wash, flush, rinse, dry)instead of "Normal" (wash, flush, wash,flush, rinse, dry), but used heated wash as per usual.

Results this morning were quite good, mind you one normally places a small amount of detergent (older formula Cascade "Complete" with phosphates) in the pre-wash cup, and fills the detergent cup to the lower line. This time filled the main wash cup full to the higher line, just to be sure. Also as per always one resets the timer after the machine fills for the final rinse to the last portion of the main wash cycle. This way the machine will give two rinses. Have found this cuts down on yibbles from all the grains (oats, rice, and flax seeds) we consume.

Still one wonders if the results were so good because due to the rather cool weather recently the boilers are still set to "Winter", thus the hot water out of the taps is >130F. As it was the machine stayed longer during the heating cycle than one remembers when using the "Normal" cycle. One assumes this because hot as the water was the dishes and dishwasher are "cold" from sitting, this obviously cools the water.

 

[rapunzel]

Salt usage

Water softening agents are usually not needed in Australia as most places here use dam water. The lime scale that is shown in the above photo must be the result of well water. Australian dishwashers don't have the salt reservoir. That feature only comes with European imports.

 

[bwoods]

pre-wash

Pre-washes have been a mainstay for most dishwashers, in the U.S., for many, many years. Just recently, due to energy/resource conservation, the prewash is starting to go by the wayside in some machines.

The pre-washes or as some say pre-rinses were designed to remove large amounts of food wastes and grind them up and dispose of them before the main wash, when the detergent was released.

Before the days of detergent tablets, one ususally put detergent in two cups. One for the first pre-wash, and the other cup opened during the main wash.

In a typical GE non-tall tub dishwasher (until just a few years ago), the normal cycle had seven water changes. Pre-wash, pre-wash, pre-wash, main wash, rinse, rinse, final rinse. There were a few models that used 5 water changes, that they made for a couple of years, and some of the electronic models had six.

I currently have a GE dishwasher, from the late nineties, that has What General Electric refers to as a "Hot Start Option"

General Electric states this is for homes that have kitchens far from the hot water heater where water may cool, in the lines, before entering the machine.

In mine, the Hot Start option adds two water fills before the normal seven. The first one is a flash rinse for about 3 minutes, to flush the lines. The next fill last for about 20 minutes and the heating element comes on to heat the water.

So in total, the Hot Start Option adds about 25 minutes to the cycle. In the newer models (see link) it only adds about 10 minutes.

When putting in really greasy, grimy cookware/dishes, I often use the Hot Start Option. Nine water changes produce dramatically clean and sparkling dishes...but not too energy efficient, ha. Using the Hot Start Option, it even outcleans my classic GE GSD2800, which was General Electric's early 1980's entry into the all electronic dishwasher.

http://products.geappliances.com/MarketingObjectRetrieval/Dispatcher?RequestType=PDF&Name=49-55076S-1.pdf

 

[washer111]

Our water here comes from an underground source. A number of cities in the country use this. Adelaide's water is supposedly quite hard, as is some of Perth's water.

And no, you cannot see the floor thru a dish drawer machine. It is the stainless steel (or composite) filter plate used during the wash cycle. There is a kidney shaped drain filter underneath the cutlery basket which I clean every day.
Water usage on this machine is 6.7Litres per wash. A Heavy Cycle for us is 124minutes, reducing to 114 with Eco. Normal cycle is 114, but goes up to 130 in Eco. The drying cycle on this machine is using residual heat and an intake/extraction fan system.

The run from cool to hot on the line to the dish-washer is roughly the amount of time it takes to fill. It takes around 30 secs to fill a 12L single flush toilet - so you can figure out my pipe run. Sometimes I will run the water hot in the kitchen so the dishwasher has a head start, although the pipes are usually fairly warm, as they run thru to ceiling.

About the Hot-Start feature - I wouldn't think it was necessary on the older machines, as they tended to use a fair amount of water for a pre-wash, wash, 2x rinses etc. Wasn't GE's first electronic dishwasher the Potscrubber Dishwasher 2500 model? Search for "Beeping Dishwasher" on YouTube, and you will see what I mean
It is a fact, that the fancier or separate Asko 1402/1502 (many options timer model and computerised model) used 32L/8Gal for a normal wash (pre-wash, wash, 3x rinse, dry). The 1402 who shared a manual with the pictured lime scaly 1302 used 24L/6Gal, with 2 rinses instead of 3. Seems like Asko needed more water to make a computer wash well - or it just needed more, since it was the fancy model with lots of custom options (make your own cycle, etc).

By they way, the Asko pictured has a COLD prewash. The 1402 model only used a 55C (or around 150F) prewash on the Pots/Pans cycle, nothing else. The dish-drawers have a cold pre-risne, I believe.