Undersink Water Heater

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  • This topic has 6 replies, 5 voices, and was last updated 24 years ago by Avatar photoArt_xyz.
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    • #273101
      Avatar photoAnonymous

        It takes several minutes for the hot water to reach my kitchen faucet. I would like to install a small electric water heater or tankless water heater for instant hot water and to feed my dishwasher. Which type is better? Will the tankless type provide a constant flow of hot water (unlike a small tank type which will run out of hot water quickly)? Is there much difference in electrical cost?

      • #286889
        Avatar photoSylvanLMP

          Tom your better off with installing a return circulation line rather than a point of use heater.

          I installed a point of use heater on a 6 story one family building only because the water was to supply one basin until the building H/W reached this point.

          The problem with under the sink heaters is volume. You may not have enough volume for a complete cycle of washing/rinsing.

          Another factor is flow rate Vs make up time and demand.

          I have installed several 220-440 Volt instantaneous heaters/boosters just for dishwasher applications but again this may be over kill for a one family home.

          Have you also considered a new product from NIBCO called just right for circulation of H/W

          Good luck

        • #286890
          Avatar photohj

            The instantaneous water heaters that you could install under the sink will never supply the volume and/or temperature the DW needs. To supply the water for a complete cycle you will need about a five gallon heater. If you have room for one at the sink then the heater will reheat between DW uses.

          • #286891
            Avatar photoGuest

              why dont you connect the dishwaher to the cold line and let the d/w heat up itself. This way you could connect an under sink heater with good flow rates. The reason these heaters suffer water pressure problems is because the thermostat is set too high. Between 50 and 60 degrees is ample for a kithen and you would get a good flow.

            • #286892
              Avatar photoSylvanLMP

                Great reply, except you haven’t read any plumbing codes it appears OR any publications by any recognized health departments.

                The actual recommended MINIMUM temperature for a dishwasher is 140-160 degrees WASH and 180 degrees for final rinse UNLESS you use chemicals for disinfection in lieu of the 180 degree temperature (commercial applications) BUT residential still require 140 MIN

                Even today there is a major concern among health officials AND LMP’s about the lower temperature H/W heaters out there (125 deg Max)

                Did you honestly expect cold water to kill ANY bacteria in a breading place (incubator) like a D/W?

              • #286893
                Avatar photohj

                  connecting to the cold water supply would not help anything. It would just make the dishwasher take longer since the water may be cooler than it is now. Setting the thermostat higher on an instantaneous heater does not affect the flow in the slightest. The low flow is set to a constant rate to let the water heat as it goes through and if the flow is too high the water is not going to get hot enough. And I hope you are referring to Centigrade when you recommend 50 to 60 degree water.

                • #286894
                  Avatar photoArt_xyz

                    “AM” is right. Most better grade domestic D/W’s have their own built in heater for the very reason SYLVAN commented about, 120 degree water heater settings.

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