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Old 27-09-2009, 12:53   #16
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I appreciate that PV solar panels can be open circuited, I was just curious why they hadn't been mentioned, along with the wind gen, for heating water.

...OK, so maybe one or two solar panels and a wind gen might not be able to power a 300watt heating element directly (depending on sizes and weather) but most cruising boats have several hundred amp-hours of battery capacity. In the example you gave, 300watts at 12volts for 2 hours = 50amps. This could easily be put back into the batteries during the course of a day by solar and wind. A 12volt timer could be used to direct power to the heating element early each morning.
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Old 27-09-2009, 14:27   #17
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As ColdFusion says ... but then it's not a DIVERSION/Dump load, just a load. PV cell don't use diversion loads, because they don't generally have any use for them. If you have PV and 12Volt HW heater, then I'd probably manually switch it (on/off) it from the battery bank.
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Old 27-09-2009, 18:42   #18
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Originally Posted by mvthankful View Post
Water First Thing in the Morning

What else is there if I'm on the hook for a month? .
Deboarah,

One of the woonderful things about being at anchor for a month is there is nothing to do. Absolutly nothing!
You can laze in bed till 10am!
You can get up early and lay in the moring sun
You can get up late and swim off the back
You can rise with the sun and take the dinghy for a row.
You can sleep in then read a book...


....... theres so many things that you will discover you can or don't have to do.

Perhaps after a few days you will be able to change your whole morning rythm to one of relaxation.

You might find the dishes don't need to be done in the morning
A shower can be taken in the afternoon after swiming & before Sundowners.

You will find there is always hot water when you need it. But on a boat at anchor for a month you may never need it!

Mark
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Old 28-09-2009, 08:34   #19
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Jim,
How does your 12v wind gen heat a 120v water heater or do you have something else?
Mike
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Old 28-09-2009, 11:51   #20
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I keep a water tank on the roof and let the sun heat it
paint it black
simple
works
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Old 28-09-2009, 12:30   #21
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yea, much of the world does it that way in warmer climes. Can probably buy a black plastic tank. How about a night blanket for insulation?
Here's a question: If I wanted to use a dark tank up top, the water would get too hot in the FL sun I'm sure. If I gravity feed the hot water to a faucet/mixing valve, will the cold pressure side push up into the tank ? or will the hot mix in properly?????
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Old 28-09-2009, 13:10   #22
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You keep the water a perfect temperature by moving the boat to a perfect temperature.
That way you don't need a mixing valve.
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Old 28-09-2009, 14:19   #23
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My ER is large enough to hold a 20 gal electric HW tank.

Very fast recovery when the Gen is running and the ambient Temp in the ER keeps it warm all night. Safe and simple
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Old 30-09-2009, 09:56   #24
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Why has there been no mention of diverting the power from solar panels too, as well as a wind gen, once the batteries are charged, or have I missed something? I appreciate they'll only work during the day but with enough insulation on the calorifier/hot water tank the water should still be hot in the morning. So why not use solar panels to power the heating element too?
Because as a rule solar panels don't generate the kind and amount of power necessary to efficiently power items such as hot water heater elements. That type of power is commonly found coming from an alternator or generator of some type, which is essentially what windmills are, i.e. a 'wind generator'.
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Old 30-09-2009, 10:40   #25
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The OP has 520 watts of solar panels. Easily enough to power the 300 watt heating element, as per the post above.
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Old 30-09-2009, 18:10   #26
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Hot water........ Whats that?


Honestly I've never had a hot water system on any of my boat(s). Sabre Dance is the first one to even have a pressure system. I pretty much live in the dark ages

There was supposed to be a water heater on the boat when I bought it but after taking apart half the galley to actually see what it was, it turned out to be a large accumulator about12 inches in diameter and 15 inches long that the PO never hooked up. When I go to rebuild the galley I'm going to put it in and use it. The dinky little quart accumulator isn't worth much. .

Anyway, If I need hot water I keep a black jerrican on the deck, and the sun gets it warm, if not hot. I can live with that for now, rather than the added complications of replumbing the boat and adding a heater or something.

I did have an idea to lay a black PVC pipe grid on the coach roof and put a slow pump on it to bring water up from a tank and run it through very slowly before putting it back into the tank. I never got around to figuring out the mechanics of it though. IT would be nice to have warm water to the shower which was also never installed but lives in a box in the head

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Old 01-10-2009, 04:21   #27
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We have a 10L instant heater which works either by heat exchange or by shore power. We use water saving shower nozzles so always plenty of hot water - in fact more than enough.
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Old 01-10-2009, 15:01   #28
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The OP has 520 watts of solar panels. Easily enough to power the 300 watt heating element, as per the post above.
Don't kid yourself. Actually, it's not. Not enough amps, usually. That is why even on large terrestrial solar panel power systems (for off grid homes) you virtually never see solar panels powering electric water heaters or any other power-hungry appliance (air conditioner, refrigerators, etc). Instead, they go with propane (refrigerators, water heaters) and passive solar (pre-heat water heater). Wind generators are for hot water heating. They've got the amps and energy to spare usually...when they're running. Which is why they are frequently hooked up to dump their load into an electric hot water heating element.
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