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Dishwasher not cleaning well: should I change supply line size ?

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  • Dishwasher not cleaning well: should I change supply line size ?

    We currently have a Bosch dishwasher, and like the two previous units (another Bosch and a Kitchen Aid) it doesn't clean very well.
    We don't put dishes in there that have dried on, encrusted food on them, and as the unit is run pretty much every day, dirty dishes are not sitting around very long so it should be handling it's assigned task much better.

    As the two previous units had the same problem, I am wondering if there is not enough water pressure in the supply line, which is 3/8" copper.
    We are on a well and pressure at the holding tank reads 53psi.
    The water goes from the holding tank through 3/4" lines, into a softener and then the the water heater, both of which are in the basement almost directly below the kitchen sink.

    I am wondering if replacing the copper supply line with a larger diameter line might alleviate the problem.

    Can anyone who has encountered, and fixed, a similar problem, kindly let me know how it was done ?

    Thanks
    Paul
     
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  • #2

    Re: Dishwasher not cleaning well: should I change supply line size ?

    Unless the supply line is very badly restricted, a new, larger one won't make a difference. The fill cycle is not time dependent. It relies on a level sensor to shut off the water.

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    • #3

      Re: Dishwasher not cleaning well: should I change supply line size ?

      Make sure that the arms swing freely and don't have any food stuck in the holes. We used to have issues with rice getting stuck in our last Asko as it approached the end of it's life, and since not enough water was coming out, the arms weren't swinging much, resulting in poor cleaning performance. I assume that you've cleaned all the filters out. I don't have any experience with the Bosch line so don't have anything concrete for you
      If a man speaks in the forest, and there's no woman around to hear him, is he still wrong

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      • #4

        Re: Dishwasher not cleaning well: should I change supply line size ?

        what detergent are you using? Wife likes Finnish Quantum Powerball. And what cycle are you using? images (1).jpeg
        sigpic
        hobby woodworking since 1972

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        • #5

          Re: Dishwasher not cleaning well: should I change supply line size ?

          We often put some vinegar in the rinse cycle and find that helps. The hotter the water the better job it will do. This may require raising the temp on the water heater.
          Bob just past Ayr

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          • #6

            Re: Dishwasher not cleaning well: should I change supply line size ?

            I remember one manual saying that it helps to run the hot water in the sink before starting the dishwasher so that the first water it draws is already hot. Also use the Heavy Duty cycle.
            Be careful when you follow the masses...sometimes the 'm' is silent.

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            • #7

              Re: Dishwasher not cleaning well: should I change supply line size ?

              Our washer is over 20 years old. It has a water level float, so level is always constant. We run hot water at the sink to have it hot 127°f as soon as washer starts filling. Every few months she cuts the water off under sink and puts a couple jugs of vinegar to cycle a couple times. It has  dial controller so it can be started already in a wash cycle. The new ones, probably not. It’s a 20 plus years Whirlpool, so was probably made in North America somewhere.

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              • #8

                Re: Dishwasher not cleaning well: should I change supply line size ?

                Originally posted by Bryan @ Woodstock View Post
                what detergent are you using? Wife likes Finnish Quantum Powerball. And what cycle are you using? images (1).jpeg
                Our run of the mill 10 year old Kenmore works best with powder detergent, name brand and /or grocery store brand. For whatever reason the pods didn't dissolve properly, resulting in poor cleaning action. We also need to run the hot water to start the cycle. A bit wasteful but that’s the price of convenience I guess.

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                • #9

                  Re: Dishwasher not cleaning well: should I change supply line size ?

                  We have a Bosch, and I find that it normally cleans well.    

                  Most the time when a dish is still dirty after washing, it is because it was poorly placed on the rack - sitting in such away that it did not have good water exposure.

                  We are also on a well, and our supply is a 3/8 flex line.

                  The two things that I have found will give us generally poor performance are:
                  1. Improper loading so that the swinging arms are blocked from spinning.   I've trained our boys to reach in and give them both a test spin right before starting the unit. I do that as well, and I'm surprised how often some small utensil or something has half fallen through the rack and is blocking the spinner.  

                  2.   Choice of soap. I can't remember which one we use right now, but I do know that I was surprised what a difference the choice of soap made. We tried like 6 different brands, and the differences between them were striking.  

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                  • #10

                    Re: Dishwasher not cleaning well: should I change supply line size ?

                    Dishwasher soap has to be hot. Hotter the better. Does your machine have a temperature booster? If so, try it.
                    Don  

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                    • #11

                      Re: Dishwasher not cleaning well: should I change supply line size ?

                      Thank you for all the responses. Didn't really expect this number in such a short time, but very much appreciated.

                      If the dishwasher works independently of the water pressure in the supply line, then the only common denominator between our problems over the years and several different models appears to be the water temperature. Our water heater is currently set at the recommended setting, there is no temperature readout, so I don't really know what its is. I could take the temp of water coming out of the kitchen tap to see, but will have to dig out the thermometer. We do run the hot water before turning on the appliance and it is supposed to have an internal heater that brings the water to the temp required by the selected cycle.
                      I have been selecting the "heavy" cycle, which according to the booklet that came with the dishwasher runs at 66-72C (151-162F). However the unit defaults to auto when it is turned off, which runs at 55-72C (126 -162F). I wonder if that's a problem as everyone else in the house just turns the thing on lol.
                      There is a "Santize" button, but the manual doesn't say what this does exactly except that it's "an option to meet sanitized conditions".

                      As for detergent, we use the powder, either Finish or Sobey's brand, which both look identical.
                      Bosch recommends the Finish tabs, but we found that they didn't dissolve very well and that the loose powder seemed to work better.
                      We were warned off using "pods" by the guy that has looked after our plumbing for the last 20yrs and the folks that pump our septic tank, as well as the guys that installed a new tank some years ago. The reason being that the material that coats the pods doesn't play well with the bacteria in the tank mainly because it doesn't always dissolve totally in the dishwasher (or washing machine).
                      I have removed the filter and the fine screen that covers the small water holding area in the bottom and noticed that it contains quite a bit of undissolved detergent. After cleaning this out the washer seemed to run better for a while, we could hear the water swishing around, but it didn't seem to clean much better.
                      I have seen a gel type of detergent at Costco, so I'm wondering if this would dissolve/work better.

                      We regularly inspect the arms for any stuck particles, and like I said in the OP, we give the dishes a real good clean before putting them in, which is sort of defeating the purpose of having a dishwasher in the first place.
                      Have not tried adding vinegar or giving it a vinegar rinse, but that is on the list.

                      Maybe all our problems have been caused by not having hot enough water, so that's the first thing to do.

                      Paul
                      Last edited by Paul O in Paris; 07-22-2020, 07:23 PM.

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                      • #12

                        Re: Dishwasher not cleaning well: should I change supply line size ?

                        Any chance you have hard water?
                        Pete

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                        • #13

                          Re: Dishwasher not cleaning well: should I change supply line size ?

                          use the sanitize, the dishwasher has a element to boost water temp
                          beachburl likes this.
                          sigpic
                          hobby woodworking since 1972

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                          • #14

                            Re: Dishwasher not cleaning well: should I change supply line size ?

                            What model of dishwasher is it?   Anything mid range and up by Bosch should result in good cleaning. We do zero rinsing of dishes before putting it in the dishwasher. Just a quick scrape into the compost bin and away we go. Dried on cooked cheese. Cake pans with stuff stuck to them. Meat chunks cooked onto pans. Etc... I actually find the dirtier the dishes the better the clean. The dishwasher then has particles to throw at the dishes rather than just water. It needs some grit to clean stuff off with.  

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                            • #15

                              Re: Dishwasher not cleaning well: should I change supply line size ?

                              I'm running a 25 year old Kenmore. I found the no-name (yellow box) to be the best cleaner and cheapest.  

                              I fill both compartments and I put a little sprinkle maybe a tablespoon on the door before I start.

                              For really dirty dishes and pots and pans I put half a teaspoon or a couple drips of liquid dish soap.

                              I always run hot water to the sink before I start the dishwasher.

                              I almost always check that both top and bottom spinners are working by just giving them a spin by hand before starting.

                              About twice a year I add vinegar (2 litres) to a regular wash.

                              The only thing I ever have to scrub by hand before the dishwasher is microwave scrambled egg bowl. For some reason my dishwasher has always had problems with egg.

                              I do believe I use too much dishwasher soap as the clearcoat on some of my favourite coffee mugs gets stripped and little speckles of dirt get dried on inside. Even some of my 20-year-old IKEA juice glasses are starting to get a light etch on the inside.  










                               
                              For every action there is an equal and opposite reaction.
                              Sir Isaac Newton.

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