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What(39)s inside the water heater -- how fast will it heat-gctid816417

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    What(39)s inside the water heater -- how fast will it heat-gctid816417

    Across the years there have been a number of questions about how fast a water heater should heat with just the engine coolant flow.

    A little bit of thermodynamics and a sprinkle of math can solve that.

    To do that I need to know what's inside the heater. I know there is a coil of metal tubing.

    How long is it, whats the diameter and what is it made of? I think it's smooth on the outside rather than having fins.

    Thanks!

    Foster
    Yep, my 4588 Bayliner IS my happy place :whistle:

    #2
    "Foster" post=816417 wrote:
    Across the years there have been a number of questions about how fast a water heater should heat with just the engine coolant flow.

    A little bit of thermodynamics and a sprinkle of math can solve that.

    To do that I need to know what's inside the heater. I know there is a coil of metal tubing.

    How long is it, whats the diameter and what is it made of? I think it's smooth on the outside rather than having fins.

    Thanks!

    Foster
    [color]blue wrote:
    Most are built using smooth OD tubing that makes a loop. No heat sink/fins...... Nothing fancy!

    My 12 gallon SS Water Heater will produce hot water in approximately 45 minutes of cruise time (no electric heating during this).

    The key is in how the Engine Coolant supply/return are plumbed at the engine.

    Many get this wrong, and it reduces the effectiveness.

    [/color]

    .
    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

    Comment


      #3
      My six gallon heater will produce hot water in about 15 minutes of normal cruise rpm 3400-3600 or so.
      2007 Discovery 246
      300mpi BIII
      Welcome island Lake Superior

      Comment


        #4
        Thanks for all the replies.

        I'm looking for some science. I can build the math to say X amount of water at Y temps will heat Z gallons in T time.

        What I need is the heat input, how big is the hot tube in the tank. For example, if the tube is 3/4" and 4' long at 170 degrees (average temp on a diesel) it will take 72 mins to heat 11 gallons of water 70 degree water to 170 degrees. A 1" long tube will take close to 6 days to do that.

        How long / diameter of the heating tube inside?

        Who has a sazall and a few mins to look?

        Thanks!
        Yep, my 4588 Bayliner IS my happy place :whistle:

        Comment


          #5
          Or you could simply say, "Hey Susan, is the water hot enough for my bath yet?"B)
          Jeff & Tara (And Ginger too)
          Lake Havasu City, AZ
          |
          Current: 2008 Playcraft 2400 MCM 350 Mag B3
          2000 Bayliner 3388 Cummins 4bta 250s (SOLD 2020)
          2000 Bayliner 2858 MCM 7.4 MPI B3 (SOLD 2018)
          2007 Bayliner 305 MCM twin 350 Mag B3s (SOLD 2012)
          2008 Bayliner 289 MCM 350 Mag Sea Core B3 (SOLD 2009)
          And 12 others...
          In memory of Shadow, the best boat dog ever. Rest in peace, girl. 7-2-10

          Comment


            #6
            "Jeffw" post=816575 wrote:
            Or you could simply say, "Hey Susan, is the water hot enough for my bath yet?"B)
            We are avoiding the "WTF Foster, what is up with the hot water for MY bath". Pay attention here :-)
            Yep, my 4588 Bayliner IS my happy place :whistle:

            Comment


              #7
              "Foster" post=816572 wrote:
              Thanks for all the replies.

              I'm looking for some science. I can build the math to say X amount of water at Y temps will heat Z gallons in T time.

              What I need is the heat input, how big is the hot tube in the tank. For example, if the tube is 3/4" and 4' long at 170 degrees (average temp on a diesel) it will take 72 mins to heat 11 gallons of water 70 degree water to 170 degrees. A 1" long tube will take close to 6 days to do that.

              How long / diameter of the heating tube inside?

              Who has a sazall and a few mins to look?

              Thanks!
              I have a sawzall. Ship your water heater to me and I will answer all your questions.
              Esteban
              Huntington Beach, California
              2018 Element 16
              Currently looking for 32xx in South Florida
              Former Bayliners: 3218, 2859, 2252, 1952

              Comment


                #8
                "Foster" post=816572 wrote:
                Thanks for all the replies.

                I'm looking for some science. I can build the math to say X amount of water at Y temps will heat Z gallons in T time.

                What I need is the heat input, how big is the hot tube in the tank. For example, if the tube is 3/4" and 4' long at 170 degrees (average temp on a diesel) it will take 72 mins to heat 11 gallons of water 70 degree water to 170 degrees. A 1" long tube will take close to 6 days to do that.

                How long / diameter of the heating tube inside?
                [color]blue wrote:
                Foster, I would contact Atwood, Seaward, Kuuma, Raritan, etc, and ask just how their engineers determined the size/length of the internal Heat Exchanger tube in order to come up with a proper design that works in most scenarios. :P

                I'm just poking fun at you...... no offense! [/color]

                .
                Rick E. Gresham, Oregon
                2850 Bounty Sedan Flybridge model
                Twin 280 HP 5.7's w/ Closed Cooling
                Volvo Penta DuoProp Drives
                Kohler 4 CZ Gen Set

                Comment


                  #9
                  If you're really looking to do an analysis, why not conduct an empirical analysis. Measure and log the temps of the engine coolant and the temp of the potable water from the heater over time. You could then derive a thermal heat transfer coefficient, which would allow you to back into the heat flux numbers.

                  Then you could tell the wife that once you get the thermostat open, she gets XX minutes of hot water for every XX minutes of running.
                  Custom CNC Design And Dash Panels

                  iBoatNW

                  1980 CHB Europa 42 Trawler- "Honey Badger"

                  Comment


                    #10
                    Just remove the bathtub, problem solved :silly:
                    Dave
                    Edmonds, WA
                    "THE FIX"
                    '93 2556
                    Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                    The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                    Misc. projects thread
                    https://www.baylinerownersclub.org/f...56-gctid789773

                    Comment


                      #11
                      "builderdude" post=816707 wrote:
                      Just remove the bathtub, problem solved :silly:
                      Yes..... that and the washing machine and the dishwasher.
                      Rick E. Gresham, Oregon
                      2850 Bounty Sedan Flybridge model
                      Twin 280 HP 5.7's w/ Closed Cooling
                      Volvo Penta DuoProp Drives
                      Kohler 4 CZ Gen Set

                      Comment


                        #12
                        Hey, since you're into doing math.....

                        How long would it take 400w @ 17V of PV panels to heat 11 gallons of water from say 60F to 110F?
                        Terry
                        1999 Bayliner 3388
                        Twin Cummins 4BTA
                        Fisherman, Cruiser, Boaticus-enthusiasticus-maximus
                        Member Royal Victoria Yacht Club

                        Comment


                          #13
                          does anyone can help me on that, I think I left my water heater breaker ON with no water ....

                          I need to know the replacement part number

                          tks

                          Comment


                            #14
                            You can buy replacements at most hardware stores. Here in Canada, about $30.00

                            The element with the square mounting flange can be installed in any orientation, but if you look closely there is an arrow pointing up that orients the heating loop vertically. I would guess it is stronger in that position.
                            2007 Discovery 246
                            300mpi BIII
                            Welcome island Lake Superior

                            Comment


                              #15
                              "TenMile" post=816786 wrote:
                              Hey, since you're into doing math.....

                              How long would it take 400w @ 17V of PV panels to heat 11 gallons of water from say 60F to 110F?
                              Not sure if you're joking, but water has a specific heat of about 4.178 kJ/kg-C in that temperature range..

                              http://www.engineeringtoolbox.com/wa...ies-d_162.html

                              11 gallons of water is 41.64 liters = 41.64 kg.

                              110F - 60F = a change of 50 F. Divide by 1.8 degrees F per degree C to get a change of 27.8 C

                              (4.178 kJ/kg-C) * (41.64 kg) * (27.8 C) = 4836 kJ = 1343 Watt-hours

                              Average capacity factor for solar in the U.S. is about 0.135, so over a year your 400 Watts of panels will produce on average (400 W)*(0.135) = 54 Watts. So it will take about (1343 Wh) / (54 Watts) = 24.9 hours. Basically one day's panel generation (since the average is spread over both day and night). There are no efficiency losses since the end product is heat, but there will be some heat losses due to (lack of) insulation. So expect it to take a bit more than a day.

                              If you want to get PV production for a specific location and time of year, use the government's PVWatts site:

                              http://pvwatts.nrel.gov/

                              Note: Water has a very high specific heat, so it takes a lot of energy to heat it up. Instead of using an electric heater, whenever possible you are much better off using waste heat from other sources (e.g. the engine) to heat up water.
                              1994 2556, 350 MAG MPI Horizon, Bravo 2

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