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The Atwood EHM6 H/W Heater manual says its a 220v unit. It also can operator from a coolant exchange with the engine (which I don't have) - so how can this run from the battery (which is 12v) when out at sea?

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    The Atwood EHM6 H/W Heater manual says its a 220v unit. It also can operator from a coolant exchange with the engine (which I don't have) - so how can this run from the battery (which is 12v) when out at sea?

    When my 275 was surveyed before purchase the water heater worked - unfortunately I don't remember how this was turned on by the Marine surveyor. I'm probably making yet another newbie mistake here but now I got my fresh water pump working and water is flowing just fine again, I can't seem to get any hot water. Batteries are fully charged, the Hot Water galley pane switch is ON and there's water in the H/W tank. Yes no hot water (or even luke warm) after 20 minutes.

    So I pulled off the manual from the Web and to say it's about as much help as a chocolate teapot is saying something. It provides little information other that to show you how you can hook it up the engine directly to get a coolant exchange to warm the water and that it is 220v. But my batteries give out only 12V right? Although there is a 220/240 flip switch in my galley panel, I've never understood why.

    So what to make sure I am not missing anything first before I pull out the heating element to see if it is burned out (even though it worked the last time it was turned on/ tested back in February.

    Am I missing something?
    2006 Bayliner 275
    Cummins Mercruiser 2.8l Diesel 200HP
    Bravo 3

    #2
    Running from 12V is not a practical option, power (watts) required is too great. Do you have a generator? You can plumb it to the engine cooling system.
    1997 Maxum 2400 SCR 5.7LX Bravo II

    Mike

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      #3
      BTY in the US they operate on 120VAC so I am assuming your or sea.
      1997 Maxum 2400 SCR 5.7LX Bravo II

      Mike

      Comment


        #4
        Is shore power hooked up and turned on.
        You have to have shore power for the water heater to work if not plumbed to engine.
        Don
        1995 Maxum 2400 SCR LUNA DE MIEL
        1988 Bayliner 2455 (sold)
        1976 Tahiti 16.5 I/O (sold)
        10 ft livingston (lost in fire )
        1987 18ft. Seaswirl cuddy (lost in fire)
        "Is it better to be on a boat thinking about God, or be in church thinking about boating?"

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          #5
          There should be a coolant hose loop from one of the mains connected to the hot water tank. This will heat the water underway or at anchor by running that engine in a pinch. If you are anchored or at a dock and not plugged in, you will need to run the generator to heat the water. You would need incredible amounts of battery to invert for the water heater. 1500 or so watts even at 240v would be prohibitive as I understand it. I will admit that trying to understand the formulas is beyond me, and I have a friend with a 49 Alaskan that is able to run his heaters and hot water heater from his inverter, so I’ve seen it done. I just don’t know how. Something about surplus submarine batteries maybe. He worked at a naval shipyard.
          P/C Pete
          Edmonds Yacht Club (Commodore 1993)
          1988 3818 "GLAUBEN”
          Hino EH700 175 Onan MDKD Genset
          1980 Encounter Sunbridge "Misty Blue" (Sold)
          MMSI 367770440
          1972 Chevrolet Nova Frame off Resto-mod in the garage
          Boating on the Salish Sea since 1948

          Comment


            #6
            As the others have said: the water heater will not heat water running off a 12volt DC system, it’s designed to heat water via your AC shore power panel OR your engines coolant system.
            Personally I’ve never operated mine from shore power as the engine does a fantastic job in heating water way freakin hotter than you need it.

            Dave
            Edmonds, WA
            "THE FIX"
            '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
            (.030 over-Vortec top end-part closed cooled)
            The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
            Misc. projects thread
            https://www.baylinerownersclub.org/f...56-gctid789773

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              #7
              "New Topic" means a subject, such as "water heater questions," not a whole paragraph. Just trying to help.
              Jeff & Tara
              (And Ginger too)
              Lake Havasu City, AZ

              2000 Bayliner 3388
              "GetAway"
              Cummins 4bta 250s

              In memory of Shadow, the best boat dog ever. Rest in peace, girl. July 2, 2010

              Comment


                #8
                Originally posted by Pcpete View Post
                ....................... You would need incredible amounts of battery to invert for the water heater. 1500 or so watts even at 240v would be prohibitive as I understand it. I will admit that trying to understand the formulas is beyond me, and I have a friend with a 49 Alaskan that is able to run his heaters and hot water heater from his inverter, so I’ve seen it done. I just don’t know how. Something about surplus submarine batteries maybe. He worked at a naval shipyard.
                Pete, I got a chuckle out of the idea of surplus submarine batteries. I can almost see them!


                But very true...... the OP would need a tremendously large size house bank in order to invert 12vdc into 240vac to heat water.
                That would be a very non-efficient means of heating water.

                Surprisingly, engine coolant heat is very effective at water heating.
                If not already connected, I would suggest plumbing it for engine coolant heat.


                .
                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
                  Originally posted by Jeffw View Post
                  "New Topic" means a subject, such as "water heater questions," not a whole paragraph. Just trying to help.
                  Jeff, are you referring to the length of the thread title (of which requires an Intermission for popcorn and beverages) as you read it?
                  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


                    #10
                    I saw this on youtube once. You're going to need a roll of duct tape and a shitload of D batteries. They HAVE to be Energizers though.
                    "REEL WILD"
                    2001 2859 FNM 300 Diesel-Bravo 2
                    Anchorage, Alaska
                    If you don't like the weather, wait 15 minutes.......

                    Comment


                      #11
                      So looks like plumbing it into the engine and using the coolant is the way to go.

                      but I want to make sure the heater actually still works first.

                      Unfortunately my marina lacks shore power - well my birth does anyway so I plugged in my portable petrol inverter generator that was dockside (provides around 2.5kw). Noticed the polarity light went on the onboard switch panel - but assumed that’s simply because the neutral isn’t linked to earth on the generator.

                      but noticed the 240ac light was also on even though the switch was in the off position - when flipped to ON the light went off but the volt meter on the panel only registered about 30 volts.

                      i flipped the battery charger switch to on and went and checked the battery charger in the engine bay - it’s amp meter reading remained at zero.

                      I had also flipped on the water heater but after 20 minute the water was still cold.

                      totally confused. Thought this would have worked.
                      2006 Bayliner 275
                      Cummins Mercruiser 2.8l Diesel 200HP
                      Bravo 3

                      Comment


                      • Nauti_Mike
                        Nauti_Mike commented
                        Editing a comment
                        Plumbed to the engine doesn’t care if the electric element is working.

                      #12
                      You have a ground fault that’s causing an issue. Something is reversed in the system, probably the neutral and earth. You may need a test meter to make sure the wire at each end of the cord. Then make sure your inlet on the boat is correct. Nothing is going to work with the reverse polarity light on. I have a pocket sensor about the length of a pen but bigger around that lights up in the presence of ac power. I’ve found it very handy when chasing these kinds of issues. I’m sure there’s a 240v model.
                      https://www.google.com/search?client..._ZMrKL1o1rv9M:
                      https://www.google.com/search?client...sPMz0istH2T3M:

                      P/C Pete
                      Edmonds Yacht Club (Commodore 1993)
                      1988 3818 "GLAUBEN”
                      Hino EH700 175 Onan MDKD Genset
                      1980 Encounter Sunbridge "Misty Blue" (Sold)
                      MMSI 367770440
                      1972 Chevrolet Nova Frame off Resto-mod in the garage
                      Boating on the Salish Sea since 1948

                      Comment


                        #13
                        You don’t think it’s simply the neutral/earth on the generator causing this? As the boat was fine under regular shore power (with same lead) at the marina I bought it from and as this is a standard inverter generator that powers normal domestic electronics requiring separate earth and neutral.

                        I’m thinking I just need to create a bridging cable to link Earth and Neutral.....
                        2006 Bayliner 275
                        Cummins Mercruiser 2.8l Diesel 200HP
                        Bravo 3

                        Comment


                          #14
                          Originally posted by Pipmeister View Post
                          You don’t think it’s simply the neutral/earth on the generator causing this? As the boat was fine under regular shore power (with same lead) at the marina I bought it from and as this is a standard inverter generator that powers normal domestic electronics requiring separate earth and neutral.

                          I’m thinking I just need to create a bridging cable to link Earth and Neutral.....
                          Where are you located? US sold boats operate on 120 VAC shore power. If you truly need 240 VAC was the boat converted? Are you certain the portable inverter is the same? What is the total load you have on the inverter?
                          1997 Maxum 2400 SCR 5.7LX Bravo II

                          Mike

                          Comment


                            #15
                            Mike -- Appears OP is in the UK.

                            OP -- I just went thru the HWH purchase/install process. After ordering the wrong unit (exchange ports on rear vice front) I thought I had the correct model to reorder when I discovered that my next one would have been incorrect due to the wrong HZ. Ensure your unit is rated 50HZ for the UK if that is still where you are. It appears they come in 220V 50 or 60 HZ.

                            With that said, it sounds as though you have some other power or grounding issues going on that may need to be resolved. Hopefully the folks here can help you get that done.
                            1998 BL Ciera 2655 Sunbridge LX (Special Edition)
                            "Sea Flights"
                            5.7L 2bbl w/Thunderbolt Ignition and raw water cooling
                            A​​​​​​lpha I Gen II Sterndrive/1.45:1 gears
                            M15.25 X 15P Black Max prop
                            MFG Extra's - A/C, Fresh Water Engine Flush port, HWH and Windlass
                            Docks @ Punta Gorda, Florida

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