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Old 01-17-2016, 09:18 PM   #21
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Quote:
Originally Posted by WesK View Post
Why would you want to heat hot water?

I am really fond of my marine water heater with heat exchanger. If you stay at the dock or in marinas exclusively, this may not be important to you but I can cruise all day, anchor, take showers and still have hot water the next morning. No electricity needed..... If it were me, I would install a marine water heater with a heat exchanger. It would be an improvement over the original.
I would tend to go with the above also. I replaced a very old rusty heat exchanger type water cylinder in our boat with an Isotemp Standard 42L unit several years ago, which as heat exchanger and element. We don't have 240v AC out on the water, so we just use the element to preheat the water by connecting it to shore power while loading up, and in 20 mins it is about bath temp hot. The engine then takes over from there and we are never out of hot water the rest of the trip. In fact the heat exchanger makes it too hot, and we have to remember we don't have the 50 C temp limiter valve on her like we do at home, and to mix in plenty of cold.

Believe it or not the old cylinder still worked, (the rust mainly in the outer lining, the tank being copper), but slowly because, (as I found out once removed), because of muck in the heat exchanger piping.
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Old 01-18-2016, 07:37 PM   #22
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Thanks S-Mike for the info regarding the neutral/ground. I bought the Lowes "water heater" but it appears to be wired normally without any connection between neutral and ground. Neither is there a sticker referencing such connection. Perhaps it is an issue that varies from State to State.
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Old 01-18-2016, 08:21 PM   #23
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Originally Posted by Capt Kangeroo View Post
Thanks S-Mike for the info regarding the neutral/ground. I bought the Lowes "water heater" but it appears to be wired normally without any connection between neutral and ground. Neither is there a sticker referencing such connection. Perhaps it is an issue that varies from State to State.
Most states follow the National Electrical Code. They might add a few things but I doubt they would change the part about grounding only at the entrance panel.
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Old 01-19-2016, 02:28 PM   #24
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Quote:
Originally Posted by Capt Kangeroo View Post
Thanks S-Mike for the info regarding the neutral/ground. I bought the Lowes "water heater" but it appears to be wired normally without any connection between neutral and ground. Neither is there a sticker referencing such connection. Perhaps it is an issue that varies from State to State.
From the picture of the grounding strap posted earlier, it appears to me that it's a 240VAC appliance, with two hot (red and black) and one ground (white) wire. No green safety ground.

It's starting to make sense. Recently an appliance salesmen was trying to sell a 4-conductor plug for my new range. I'm guessing there's a push underway to add a safety ground to all 240VAC appliances, like we have in the 120VAC world. It's not a bad idea. I had an old range once that would give you a shock if you touched it while touching anything else that was grounded. Needless to say I replaced it.

Of course, you'd need to remove the bonding strap to convert your 3-wire appliance to a 4-wire plug. I might just do that when I install my range. Only I'll buy the cord on line for half what they wanted to charge me.

And, if Capt Kangeroo bought a 120VAC water heater, that might explain why it's wired "normally" and without a sticker. Most boats in the 30-35' range have smaller water heaters (6-12 G) that work on 120VAC, as do some "apartment size" heaters. Full-size home units and larger boats will use a 240VAC supply.
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Old 01-19-2016, 02:32 PM   #25
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Originally Posted by CaptTom View Post
From the picture of the grounding strap posted earlier, it appears to me that it's a 240VAC appliance, with two hot (red and black) and one ground (white) wire. No green safety ground.

It's starting to make sense. Recently an appliance salesmen was trying to sell a 4-conductor plug for my new range. I'm guessing there's a push underway to add a safety ground to all 240VAC appliances, like we have in the 120VAC world. It's not a bad idea. I had an old range once that would give you a shock if you touched it while touching anything else that was grounded. Needless to say I replaced it.

Of course, you'd need to remove the bonding strap to convert your 3-wire appliance to a 4-wire plug. I might just do that when I install my range. Only I'll buy the cord on line for half what they wanted to charge me.

And, if Capt Kangeroo bought a 120VAC water heater, that might explain why it's wired "normally" and without a sticker. Most boats in the 30-35' range have smaller water heaters (6-12 G) that work on 120VAC, as do some "apartment size" heaters. Full-size home units and larger boats will use a 240VAC supply.
Pretty much what I was thinking....having wired a couple small home units on a boat...I had never seen them wired differently than a marine unit as they were 120V....and never say that sticker.
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Old 01-19-2016, 02:46 PM   #26
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Originally Posted by WesK View Post
I see it but I don't believe it. My recollection of the National electrical Code only allows connecting the neutral and ground together at the entrance panel.


It's been years so maybe it's changed or my memory has failed me.

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Old 01-19-2016, 02:50 PM   #27
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We rarely used the electrical heater as the engine coolant heater would supply several days of hot water for showers. Only problem as that care was needed because the water was too hot.
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Old 01-19-2016, 05:18 PM   #28
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Good discussion. Bleeding (Stray) voltage/amps into the water kills folks every year, especially at marinas. If you are on the hook and have the genny running and your HWH is on and it is putty stray voltage into the water, anyone jumping into the water is basically dead. Please be careful.


When I built my dock, I made sure I had a "floating" neutral. No ground until the source which is on land.
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Old 01-19-2016, 05:59 PM   #29
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Full-size home units and larger boats will use a 240VAC supply.
My 17 gallon Torrid uses 110V. I prefer glass lined tank with engine heat exchanger so stuck with boat variety tank on last replacement.
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Old 01-20-2016, 07:41 AM   #30
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"Full-size home units and larger boats will use a 240VAC supply."

True BUT the heating element is only $20.00 or so and the operating thermostats dont care.

RHEEM sells plastic lined super efficient (commercial and home) units that do not wear out inside.

The alt energy folks sell double wall heat exchangers that can later be installed/

The double wall is because anti freeze is a poison.

http://www.rheem.com/product/residen...aters-marathon
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Old 01-20-2016, 08:22 AM   #31
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We rarely used the electrical heater as the engine coolant heater would supply several days of hot water for showers. Only problem as that care was needed because the water was too hot.
Ours is like that as well. If your engine has a 180 degree thermostat, your hot (potable) water will be the same temperature and that is a hazard. On the other hand, mixed with cold water, the limited amount of hot water will provide more warm water for showering and washing dishes.

You can buy and install a mixing valve that automatically reduces the output to a safe 120 degrees or so. If you have children on board this would be a good idea. We understand and know how to deal with it.
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Old 01-21-2016, 07:21 AM   #32
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"You can buy and install a mixing valve that automatically reduces the output to a safe 120 degrees or so."

There are "tempering valves" and "anti scald valves" BIG DIFFERENCE.
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Old 01-21-2016, 12:49 PM   #33
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Since we're going down that path...

My last boat was the first one I've owned that had a water heater with an engine jacket water coil in it. I'd never go back. For me, it's one of the best modifications you can make.

As was pointed out, we always had to deal with really HOT water. Adults, and kids big enough to reach the sink, were told to be careful. We'd all forget once in a while, but that first touch of too-hot water was a good reminder. Nobody ever had to be transported to the ER. Nobody ever even needed first aid.

I'm all about safety. I don't want to say there's no danger. Certainly scalding is possible, but I suspect you'd have to work at it.

Still, my main reason for buying a mixing valve was to hopefully allow the hot water to last longer. Here's the one I installed in the fall. Can't wait to try it out next season:
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Old 01-21-2016, 02:29 PM   #34
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For those who spend time at anchor, there is a value to having the engine coolant connection to heat the water. With only a 110v heating element one is dependent on the generator working and will be without hot water if (when) the generator goes down. The engine coolant feature gives a backup by just running the main engine for 30 minutes.

We are in a world were everyone anchors and I have several friends who have gone for weeks without a generator and have used the main engine (and wind and solar) to charge batteries and also heat water. Given the low price I just paid for my new Isotherm 24 liter unit (6.4 gallons) I can't see a real value in going with a non-marine unit.
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Old 01-21-2016, 08:36 PM   #35
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Thanks to all for great advice as usual. Thought I should close this thread with my findings. I installed the 19 gallon Whirlpool water heater from Lowes and so far am pleased with it and all in all I find it a better built unit then the "marine" Raritan it replaces. Unlike the Raritan it has a bottom drain and both side and top piping connections to facilitate any mounting arrangement. Same goes for the safety valve. It takes about 20 to 30 min to heat up and we are finding the water still warm enough to shower with 6hrs later. All and all I am pleased with the unit.

The only negative is since it was not intended for boats, it had no way of securing to the floor but this was easily solved by several L brackets screwed to the floor and using the existing bottom plate fasteners. I also noted the internal wiring was solid wire versus copper strand.
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Old 01-22-2016, 07:04 AM   #36
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Many marine units have the emergency overheat cut out sensor very near the heating element.

This is so the heating element will not burn out if the system has no water.

No water is rare in a dirt house , easy in a boat.

To use a house unit you might want to install a check valve to keep the HW tank from draining back, and be sure the accumulator is after the check valve so it can accept the expansion of the heated water,

A house unit can easily be retro fitted with a heat exchanger so the main engine or noisemaker or even solar can heat the domestic water.
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Old 01-22-2016, 10:55 AM   #37
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If you're nor going to use a heat exchanger, no reason to go with a marine unit. Just make sure you properly secure the new unit.

BTW, it's a water heater. You don't heat hot water.

Ted
So technically, we should be calling them 'cold water heaters'?
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Old 01-22-2016, 11:15 AM   #38
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So technically, we should be calling them 'cold water heaters'?
Nope, just "water heaters". They heat water.

BTW: It was a plumber friend I worked with who corrected me on the "hot water heater" thing many years ago.
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Old 01-22-2016, 12:39 PM   #39
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I just installed an Isotemp 8 gallon unit. May sound small, but a guy I know who has one says the built in mixing valve tends to double the capacity. We shall see. Engine or AC-heated, SS tank and it can be mounted horizontally (as shown) or vertically. Since this photo was taken, I removed the platform it's on and bolted the wh to the bulkhead; this allowed me to lower the unit to make room for a new charger/inverter above it.
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Old 01-22-2016, 03:11 PM   #40
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I just installed an Isotemp 8 gallon unit. May sound small, but a guy I know who has one says the built in mixing valve tends to double the capacity. We shall see. Engine or AC-heated, SS tank and it can be mounted horizontally (as shown) or vertically. Since this photo was taken, I removed the platform it's on and bolted the wh to the bulkhead; this allowed me to lower the unit to make room for a new charger/inverter above it.
I have the same unit...2 showers back to back no problem...

I just don't like the proprietary heating elements...after my first one...I may make an adapter for a conventional one.

The good news is the 750 watt element heats as fast or faster because of design and insulation than the cheapo 6 gallon models with fiberglass batts and only 750 watts allows more appliances on that 110V buss
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