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Old 30-05-2013, 11:43   #16
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Re: Instant electric shower system?

3000 Watt / 12 volt / .84 inv eff
= 298 amp draw from a 12 VDC battery bank

much more than my inverter can handle (Heart Freedom 20)
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Old 30-05-2013, 11:51   #17
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Re: Instant electric shower system?

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Originally Posted by Cotemar View Post
Looks like it will need 3000 watts to take a good shower with on demand tankless.

CORAL Tankless Hot Water Heater Electric Shower Head 110 Volts Showerhead - Amazon.com

Compact Exquisite Design: The water heater's compact design, the size of shower head, takes up reduced space and attractively decorate modern living spaces. Multiple Uses: This amazing instant water heater is designed for one point of use at a time. It is Ideal for small apartments, flats, hunting cabins and small homes as well as boats, campers, RV's and mobile homes. It delivers over 40 gallons of hot water an hour with a 45 degree rise in temperature. This means that if your tap water is at 65 F, it will instantly deliver 40 gallons of hot water an hour of water at 110 F. Infinite applications can be found for the extraordinary Excel tankless water heater. Our customers also use them for washing stalls,horse trailers, de-icing cars in the winter, outdoor camping, RV s, motels, small roadside restaurants and other situations where endless and economical water heating is required . Used in Australia, Europe and Japan for many years, this technology is now revolutionizing the way we heat water in America.
The coral numbers don't quite add up... 40 gph at 45 degree F rise is 15000 btu's or 4.39 KW per hour. That's for a .66 gpm flow rate BTW. For the 2800 watt input listed to get 45 degree f. rise you would need to reduce the flow rate to .42 gpm.
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Old 30-05-2013, 12:20   #18
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Re: Instant electric shower system?

I've used one of these devices in both Trinidad and Guatemala. Great idea, but too much electrical draw for your average boat unless you've got a generator. A fairly large one. The one I spent the most time with was 3000W. At 120V it pulls 25 amps, makes blue sparks when turned off, and when enough calcium builds up and starts spraying water everywhere gives you a gentle shock when you get to close to it.
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Old 30-05-2013, 12:34   #19
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Re: Instant electric shower system?

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... gives you a gentle shock when you get to close to it.
With AC current it only takes about 30mA (0.03 Amp) to cause ventricular fibrillation of heart. Nothing gentle about that.
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Old 30-05-2013, 15:23   #20
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An inverse relationship between flow rate and temp is real. I can see this working well in the tropics where the water temp would already be fairly high but would be more a problem in cooler climates. I really would investigate the possibility of installing a propane one. However, Aside from the increased complexity of a safe install they're a lot more expensive than the electric versions apparently are.
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Old 30-05-2013, 22:21   #21
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I have some Titan water heaters for the main circuits. They are 220 volt and 29 amps and provide really hot water. Over 6000 watts.. I also use a small 110v unit for the galley

Any 110v unit is only going to give you warm water and be useless for a shower.
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Old 30-05-2013, 23:39   #22
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Re: Instant electric shower system?

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Originally Posted by sailorchic34 View Post
The coral numbers don't quite add up... 40 gph at 45 degree F rise is 15000 btu's or 4.39 KW per hour. That's for a .66 gpm flow rate BTW. For the 2800 watt input listed to get 45 degree f. rise you would need to reduce the flow rate to .42 gpm.
You beat me to it again. Propane fired, tankless, instant on demand works good at decent shower flow rates. Electric units that work almost as well pull 17 Kw, a bit more than an inverter will tolerate, not to mention the huge lead acid battery voltage sag.

sailorchic34, as always, your right again.
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Old 31-05-2013, 00:23   #23
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Re: Instant electric shower system?

I have a great unit installed ( 10ltr Duoetto ) 12vlt- 25amp 240vlt-4.6amp you will find it at www.australiandirect.com.au have a look there might be the same unit in the US for you with 110vlt. It does work as per the blurb. When I am out I turn it on when motoring and anchoring ( using 12vlt ) and there is plenty for two showers or it will be fully hot it has an adjustable thermostat in 20 30 mins Great unit Cheers Jacko
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Old 31-05-2013, 12:19   #24
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Quote:
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You might need a decent inverter. Its rated at 3000w. I can remember similar systems in beach shacks 40+ years ago. Saw similar being used in Cuba a couple of years back instead of hot water systems with tanks.

Certainly cheap, maybe nasty????????
Can be nasty. Couldn't figure out why I had a bad headache in the shower, and where the strobe light was coming from. Went away every time I opened my eyes... finally clued in and was about to shut off the shower before I got out of the water, stopped just short of a very shocking and possibly terminal experience I would have got completing that circuit to ground.

Was bad enough the electrification through the water. It didn't do much for my remaining brain cells I suspect.
Unit was only 1500w, you just restrict water flow on the head until you get enough heat. Replacement coils are cheap, often installed right after the first serious zap.
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Old 31-05-2013, 12:28   #25
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Re: Instant electric shower system?

Solar shower's worked great in the warmer climes. Used engine heated water at colder times. I still debate whether to augment heating with a on demand device. This would only be used at dock, or while running the generator (i.e. avoid if at all possible). Something that pulls that much power in that short a period requires a BIG battery bank, then you have to put it back.

Solar showers are about $15 US. KISS.
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Old 01-06-2013, 11:00   #26
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Re: Instant electric shower system?

I used a 4.5 gallon mini tank on my PDQ cat. 110v 1200w max ran off 2k inverter charger just fine. Used a Honda eu2000 to keep the batteries charged when the wife and daughter were on board.
Steibel electron or something like that I think
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