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Thread: Is it the Dishwasher?

  1. #1
    DIY Junior Member sgm50's Avatar
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    Default Is it the Dishwasher?

    Hello,

    Looking for some ideas/advice.

    I moved into a house and inherited a KithenAid Dishwasher circa 1987 (Monterey Superba 21). It is functioning well in the sense that its timing/control mechanism is newly replaced (under home warranty). It has good water supply and drains well.

    The problem is that it leaves residue all over the dishes. It is a milky color and sometimes I find grainy residue like a fine sand.

    One problem I know is that I have Hard water. I suspect that may be part of the problem. The innards of the machine where pretty built up. I have taken it completely apart and cleaned the hard water deposits (I did a very thorough job). About 6 weeks later I noticed build-up has already undone my work. I know the water is hard, but not THAT hard. I can actually scrape off "creamy" like residue off of the drain areas. The consistancy is like hand lotion. What in the world is this? I'm pretty sure it is not the soap. Other fixtures (showerheads, faucets etc...) are not affected much by the hard water and don't show this kind of buildup.

    Here's my real dilemma, I could buy new but am worried that this could happen to the new one as well. I hate to buy unnecessarily. Really, how much has the dishwashing "Technology" changed. I will eventually get a softener but I just don't believe the hard water could affect it this much and this quickly. I will buy new if I have to, but this is more a puzzle than anything.

    Your ideas are appreciated.

    -Scot

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    Plumber Cass's Avatar
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    I have seen that a few times and while I'm not sure of your problem the ones I saw the problem was the heater wasn't getting the water hot enough during the wash cycle.

    This old mind can't remember what it should be but 140F minimum rings a bell.
    Last edited by Cass; 03-28-2006 at 11:33 AM.

  3. #3
    DIY Junior Member sgm50's Avatar
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    I'll test the water temp. I assume it's OK. The sink next to it gets pretty hot and I have an Instant Hot Recirculator. I'll still test it though. That does make sense. That and pressure are my thoughts as well.
    Thanks

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    Retired Defense Industry Engineer jadnashua's Avatar
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    In my limited experience, it is almost certainly the temperature of the water. Some of the dishwashers have a water heating capability to ensure proper operating temp. You might also consider switching to a different detergent. The liquid ones vs the powder disolve easier. The powdered stuff needs the really hot water. I had a similar situation until I replaced my DW with a new one that offered to heat the water.

    Keep in mind that the water cools off in the pipes when you dont' run it for awhile. The dishwasher doesn't use thatmuch water, so the first gallon or so (maybe more) is cold. This limits the overall temp of the water, even if it eventually does get hot enough on the supply, you have a bunch of cold water in the tub.

    Try running the nearest tap until the water is as hot as possible, then start the thing up.

    With the recirculation, this should not be as big of a problem as without it.

    Also, note the HWH temp setting...for an experiment, try turning it to high for one cycle, and see if the problem goes away.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member sgm50's Avatar
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    Well, I'm starting to think we are on to something. The water temp was lower than I expected. I'm gonna turn it up and see.

    I have to think this is very common. Most people set their HWH to 120F for energy reasons right? This implies a new machine isn't gonna make a difference, unless it heats the water itself.

    I use a liquid detergent now, but was the store brand (Costco's Kirkland). I think I may try a premium brand to see if that helps.

    Thanks for all your thoughts & ideas.

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    Plumber Cass's Avatar
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    Does your DW have a seperate heater to get the water up to temp?

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Most dishwashers like the water at least 130 degrees, and some want or will make it hotter to help sanitize things. Can't get too hot, or it will deform some plastics, though. If you do replace it (or should I say when), get one that monitors the water and heats it as necessary. Also, another feature that seems to work is one with a water clarity sensor...it looks at the water as it is washing things and stops when there is little to no crud left. Lightly soiled dishes...short cycle, water savings; really dirty things, longer cycle, more water. Cleaner dishes without excess water. More water = more energy, so you end up saving in both electricity, gas (assuming a gas hot water heater), and water/sewer charges.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  8. #8
    DIY Junior Member sgm50's Avatar
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    Quote Originally Posted by jadnashua
    If you do replace it (or should I say when), get one that monitors the water and heats it as necessary...
    Well said! Now that my wife is involved, I'm sure I'll be sporting a brand new DW very soon. Not exactly my idea of a fun purchase, but at least I now know some of the features to look for. Thanks everyone for your thoughts. (I'm still gonna work on the current DW 'til she finally breaks!)

  9. #9
    DIY Junior Member sgm50's Avatar
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    Default Back to the Dishwasher Problems!

    OK, Since I last wrote about an old dishwasher that left residue on my dishes, I have broken down and put in a Brand New Consumer Reports recommended Dishwasher. This thing has all the features that have been mentioned in this thread; water clarity sensor, seperate heater for water temp, internal disposer etc...

    I installed it yesterday and went to bed with great expectations of crystal clear dishes meeting us in the morning. Wrong! The dishes seem almost worse. You can actually wipe off with your fingers a white dust from the glasses. What is our problem?

    Here are some variables:
    -I suspect hard water (I'm going to have it tested this afternoon), but I don't think it is crazy hard. I'll let you know.
    -Water temp coming in - not a problem given I have instant hot and a seperate heater in the DW. I've checked temp in past and is plenty hot
    -Soap - I'm using the premium stuff. Also, added the JetDry stuff (I don't trust that stuff)
    -Water pressure - I didn't replace the old copper tube for the water in. I was lazy, did everything else though. If the water is hard and that tube is old, then maybe it is clogged and afecting pressure. I will be replacing that soon. Could this be the problem? I thought that it may affect how quickly the tub fills up, but once full doesn't the internal pump do the circulating of water?

    I am at my wits end on this! any ideas?

  10. #10
    Retired Defense Industry Engineer jadnashua's Avatar
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    A dishwasher is sort of like a washing machine...it has a level sensor and waits until the water reaches the proper level before it starts...low incoming water pressure will only cause it to extend the cycle length - once it fills (and heats, if necessary) it starts.

    This is strange...I had a similar thing until I changed the DW to one that could heat the water.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  11. #11
    DIY Senior Member SteveW's Avatar
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    How much detergent are you using? I wonder if it's too much. My DW will sometimes leave a little white residue when my wife puts too much detergent in the cup.

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    DIY Junior Member sgm50's Avatar
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    Yeah, I had the same thought about the pressure, once it fills to a point it is on its own. May take a litle longer to fill, but so what? Right?

    Detergent - Good thought there too. We have done a lot of detergent as recommended when you have hard water. And we also have gone the route of a little detergent. To be honest, I think less detergent works better. Also, no "heat dry" kind of helps.

    OK, since last post, I have replaced the water source hose and tested the water hardness. Hose, may or may not help we'll see. either way it is good that it is changed. Hardness is 250 ppm. Now, I don't know how that translates. I would think that is on the acceptable range. Is that a good hardness?

    I just has to come down to temp and detergent getting (not getting) broken down....
    Last edited by sgm50; 06-22-2006 at 04:15 PM.

  13. #13
    DIY Junior Member sgm50's Avatar
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    Default Water hardness table

    Found this on-line. If I had 250ppm, according to the chart I'm at "Slightly hard". Is that right?

    ++++++++++++++
    DEGREE OF HARDNESS EXPRESION.

    SOFT: LESS THAN 1,6 mmol/l = 160 PPM = 9 odH

    SLIGHTLY HARD: 1,6-3,2 mmol/l = 160-320 PPM = 9-18 odH

    HARD: 3,2-4,6 mmol/l = 320-460 PPM = 18-26 odH

    VERY HARD: ABOVE 4,6 mmol/l = ABOVE 460 PPM = ABOVE 26 odH

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    Writing, constructionDIY Member Yersmay's Avatar
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    This is a wild guess. I've read that hot water can get crappy when the annode tube in the main hot water heater has deteriorated. Could this problem be traced to the main hot water heater?

  15. #15
    DIY Junior Member sgm50's Avatar
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    Would you notice it in other hot water uses ie bath, shower etc...?

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