Is it the Dishwasher?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by sgm50, Mar 28, 2006.

  1. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    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
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    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: Mar 28, 2006
  3. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    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
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    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.
  5. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    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.
  6. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Does your DW have a seperate heater to get the water up to temp?
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    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.
  8. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    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. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    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. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,266
    Location:
    New England
    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.
  11. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    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.
  12. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    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: Jun 22, 2006
  13. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    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
  14. Yersmay

    Yersmay Writing, constructionDIY Member

    Messages:
    62
    Location:
    Los Angeles
    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. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    Would you notice it in other hot water uses ie bath, shower etc...?
  16. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Messages:
    1,328
    Location:
    Columbus, OH
    That's actually good stuff. I'm more familior with a product called RinseDry, it'll help prevent spotting, but not gunk like you say.

    Try this:

    Hand clean some dishes until they're nice and shiney. Run them through your new dishwasher like you normally would, but without any soap or JetDry. What comes out?

    Does the gunk/sandy stuff disolve in vinegar?

    Jason
  17. chris8796

    chris8796 New Member

    Messages:
    100
    Location:
    Illinois
    I would say its hard water. I have water 15 grains/gal (~250 ppm) and had the same problem. You can try a rinse aid and see if that helps. But dishwasher detergent is extremely alkaline and most polyvalent metal ions (Ca, Mg, Fe) form insoluble hydroxides between pH 7.5-9 (dishwasher detergents can be pH 11). Try the vinegar test, (its pH 3-4) if it dissloves it then hard water is your problem. The more expensive dishwasher detergents and the rinse aids (weak acids) help, but usually dont totally eliminate the problem.

    Buy a water softner, we use ~200 gals/day and go through about 300 lbs of salt a yr. So its not that big of a hassle or cost and well worth the trouble for other reasons.
  18. sgm50

    sgm50 New Member

    Messages:
    21
    Location:
    Arizona
    Crazy

    I have really come to the conclusion that it has to do with the detergent disolving or not. ...and that seems to be directly related to the water temp, the detergent and the water hardness and a combination of all three factors.

    With my new DW, I have been using the hottest and most use of water settings. I use the Pots and Pans cycle and High Water temp and Sani Rinse. This helps immensely, I figure the water is heated the most and the dishes get the most exposure to spraying water for a good rinse. I turn off the heat dry, that seems to cause the spotting more than stop it. I also turned up the JetDry stuff, (to add more), seems to be helping. In addition, I try to use less detergent.

    Next, I tried the expensive Cascade Complete detergent. I actually think it is worse. Doesn't seem to break down as much. When I use the Costco branded liquid stuff, it does better. I'm gonna go get a powder version and try it next.

    Finally, the detergent not disolving as well could be because of the hard water. My previous house (just 9 months ago) had the softener and an old DW and never had these problems. It was in the same neighborhood.

    Vinegar absolutely works great to clear up the glasses and dishes. I try to clean them up before I perform my experiments for some baseline.

    Conclusion is I need a softener, but can't afford it right now ($1000 w/intall). So, I will have to be sure to choose the right combination of settings and detergent.

    I think I've beaten this subject to death, funny how obsessed you can get! Thanks for all your responses!
  19. chris8796

    chris8796 New Member

    Messages:
    100
    Location:
    Illinois
    Dont forget you'll need an electrical outlet and drain when you looking for a place to install your new softner when the funds become availalbe.

    If you have the time you should consider learning some basic plumbing skills. You can buy a pretty nice softner for $400-500 and installation is "usually" pretty straight forward. The skills may also come in handy when you need to replace the hot water heater because its full of hard water deposits.

    Good luck
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