12-volt water heater?

[tbishop]

Hello.

I'm not sure where else to post this, so I'll just do it here. I'm looking to build a small cabin in the future. I want to power it with a couple of windmill alternators. I also want to heat it with radiant floor heating. The two things I need to locate are a 12-volt water heater and a 12-volt pump. Does anyone have any suggestions for this? I'd appreciate it.

Tim

[BackwoodsIdaho]

I would look at a 120v pump and a propane water heater. Electricity is very inefficient to heat water with. 12v pumps do work but don't give a really good pressure but will work with a small pressure tank. I think you would be much happier with an inverter, batteries and a 120v water pump.

The problem with using 12v to heat water is that the heating of water is a function of watts which is volts x amps. The lower the volts, the more amps you have to push thru the wire to heat with. That means extremely large wire and high expense if you could even find such a heater. I would go with propane

jim

[Janon]

Yup, heating water with 12vdc would be a nightmare of inefficiency, propane is the way to go.

12vdc water pumps are available (any RV place), and they do work fine if, as mentioned, you do not need very much pressure and are pumping relatively short distances.

A camping travel-trailer or partially wrecked-blown-engine motor-home would be a great source of equipment to furnish a small cabin: propane stove-oven, refridgerator, water heater, small furnace, holding tanks, etc.

cheers,

[Thumper/inOkla.]

If you system is large enough to make excess power on very windy [or with solar panels very bright & clear] days
then the excess power can be used to heat water. The best place to get the info you are wanting is at www.homepower.com and through www.backwoodssolar.com

One thing I was taught was that electric heaters don't care what kind of power they get, they are basicly a dead short, you use what is called a "diversion charge control" to shunt the excess power to the heating element. and efficiency is relative, if like us you heat wash water on the wood stove, and the water heater is just to store the extra electric as heat, like to help keep a green house warmer over night, then it may be worth it.

[tbishop]

Originally Posted by Thumper/inOkla.

If you system is large enough to make excess power on very windy [or with solar panels very bright & clear] days
then the excess power can be used to heat water. The best place to get the info you are wanting is at www.homepower.com and through www.backwoodssolar.com

One thing I was taught was that electric heaters don't care what kind of power they get, they are basicly a dead short, you use what is called a "diversion charge control" to shunt the excess power to the heating element. and efficiency is relative, if like us you heat wash water on the wood stove, and the water heater is just to store the extra electric as heat, like to help keep a green house warmer over night, then it may be worth it.

Thanks to everyone for the replies so far. I did find one site that had a 12 volt element that you could use to do exactly as you said- "burn" off extra energy.

Otherwise, I wasn't very clear. I'm sorry- I'm new to the concept. I was going to use the water heater to heat the water (actually, I was going to use anti-freeze) for the radiant floor heating. I would do the rest of the heating of water manually.

So after doing some research and reading all these posts, I think the best way to go about it would be to use the propane water heater as mentioned, which would allow me to hook up a propane stove/oven too. I've found some fairly powerful 12 volt online pumps that can pump a variety of liquids, so that might work. But If I move to a whole inverted set up, I might as well do 120v. Anyway, I appreciate all the help!!

Tim

[Windy in Kansas]

I'm glad that you told more of what you wanted to do with the 12 volt heated water/antifreeze. I agree that the 12 volt water heating would have been futile, save for dumping excess.

The newer inverters are quite efficient even at standby. I think you would be money ahead to purchase an inverter, then use a 110 volt pump of high efficiency, i.e. low wattage.

I don't know what you will be lighting with, but I recommend using an invertor to power the newer compact fluorscent bulbs. I have a 7 watt bulb that puts out a lot of light. I also use 10 watt and 13 watt bulbs which provide more than enough.

[Jack in VA]

You can always use the sun to help heat your water.

[Thumper/inOkla.]

For heating a radiant floor system, useing passive solar would do much of it well if you have a large enough storage, for the heat in the system, home power had an artical about a large greenhouse (I think) in Wisc. that used really big solar collection panels, it had a conventional water heater as back up.