Author Topic: solar water heaters (Read 3432 times)

Propwash · « **on:** November 01, 2005, 01:45:35 AM »

Hello all

I have started construction of a 12' turbine with the intentions of heating my boiler water in one way or another. I have noticed many other posters with the same intentions. Most all of the posts have ended with the advice from others that a solar water heating system works much better than using turbine power for water heating. I have not seen much mention of climates. Do these solar water heating systems work in areas where temps are below zero for weeks on end, it is overcast and snowing for days, wind chills reach -50, and you have a sunny day once or twice a week at most? It's the price we have to pay to live with out tourists for 6 months. Looking forward to some input. Thanks in advance from the coast of Maine!

Nando · « **Reply #1 on:** October 31, 2005, 07:16:54 PM »

Maybe you need a few tourists to keep you warm during those COLD winters :>}

Hydro turbine works better that solar for heating.

You may be able to have Solar heating in winter if the design is well insulated for the heated medium not to give out its heat to the cold environment.

One needs to remember that the SUN is there with its energy that can be harvested.

Of course in not Sun due to clouds then bad luck .!!

Propwash · « **Reply #2 on:** October 31, 2005, 08:12:07 PM »

Thanks for the reply. 40 mph winds are more of a daily occurance here than sunny days during the winter months. My reasoning is that it would be much more entertaining to watch a wind turbine fly apart than to watch a solar system freeze up and split open. LOL. Since my origional post I have found some information on a solar water heating system used here in Maine during winter months. There seems to be no lack of information on this site. Thanks again!

Scotth · « **Reply #3 on:** October 31, 2005, 10:01:26 PM »

Check out windturbine.ca,they have an interesting line of solar water heating gear that will not freeze and is very efficient.A friend of mine saw a demo on a cold day in January a couple years ago.He said after a few minuits in the sun you couldn't touch the end of the collector it was so hot.I'm considering it for my place as soon as funding permits.

benjamindees · « **Reply #4 on:** November 01, 2005, 07:12:34 AM »

The solar water heaters are much better these days. They have vacuum tubes and selective absorbers. You can get one for almost any climate. They are also much more economical at heating than a wind turbine, but only when there is sun.

That having been said, using a wind turbine as heat is not an awful idea. It's perfectly doable with just an electric heater element. But the average 10' wind turbine, at 160 watts, won't do anything but offset a tiny amount of heating costs. It's not a "move to the woods and live off the land" type of solution.

For instance, I would need like 28 of them to heat my tiny house through December. But it is an easy way to make use of your wind turbines until you have enough to justify a large battery pack and grid independence. With four or five wind turbines, you might be able to power your water heater.

RP · « **Reply #5 on:** November 01, 2005, 10:39:42 PM »

Especially with 40mph winds!

Propwash · « **Reply #6 on:** November 02, 2005, 04:14:29 AM »

Thanks for the input. I was a little misleading on my initial post. I do realize that I can not heat my entire house with wind turbine power from a 12' turbine. My plan was to focus all of the energy created towards the reduction of my monthly oil bill. I am a backwards thinker. Build the turbine and then use it for what ever works the best. I had ruled out solar water heating because I didn't think they worked that well in this area during winter months. Even on this site I read conflicting posts about the success and failure of these systems. It seems from the posts that I am reading that storage is key. If solar hot water is made and stored when available and dc amps are made and stored when available in a battery bank and both of these sources are applied in some way to help in the production of boiler hot water then I should use less oil to heat the water. Does this scheme make sense?

elvin1949 · « **Reply #7 on:** November 02, 2005, 04:47:42 AM »

mikey ny · « **Reply #8 on:** November 02, 2005, 05:07:03 AM »

"I am a backwards thinker"

Your thinking, my friend, is quite clearly very forward. Alot of us tinkerer folks build things for the sake of building or simply because we can, and then learn enough from it to build something that serves a purpose.

Mike

GaryGary · « **Reply #9 on:** November 02, 2005, 09:11:59 AM »

Hi,

"I have started construction of a 12' turbine with the intentions of heating my boiler water in one way or another. I have noticed many other posters with the same intentions. Most all of the posts have ended with the advice from others that a solar water heating system works much better than using turbine power for water heating. I have not seen much mention of climates. Do these solar water heating systems work in areas where temps are below zero for weeks on end, it is overcast and snowing for days, wind chills reach -50, and you have a sunny day once or twice a week at most? It's the price we have to pay to live with out tourists for 6 months. Looking forward to some input. Thanks in advance from the coast of Maine!"

You can get a pretty good idea how much energy you will get out of a solar water heater collector at the SRCC site. http://www.solar-rating.org/ They test and ceritify solar collectors.

Just download the test report document (the full one). Look at how much heat the panels collector for service catagory "D" -- this is for cold weather. They have sunny day, partly cloudy and cloudy day data. They also have data on flat panel collectors and evac tube collectors.

If the SRCC says (for example) that a particular collector will collect 30K BTU/day, then you can heat 50 gallons (400 lbs) of water by this amount with the 30K BTU:

30000 BTU *(1 lb-F/BTU) / 400 lb = 75F (eg from 50F to 125F)

Most people with solar water heaters don't get full water heating throughout the winter -- this would typically take a lot of panel area and storage tank area. But, if you get nearly 100% for 3 seasons, and 50% for the dead of winter, thats still a pretty good saving for a lot less money and work than a 12 foot turbine (thou I'll grant the turbine might be more fun :-)

My site has a lot of free plans for DIY solar stuff, including lots of solar water heaters. Living in Maine, you might be interested in the one from the Maine Solar Energy Association -- its very cheap, and would probably work year round --

http://www.builditsolar.com/Projects/WaterHeating/msbatch.htm

Water heater plans and info here:

http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm

Lots of solar projects:

http://www.builditsolar.com/Projects/Projects.htm

Gary

Propwash · « **Reply #10 on:** November 02, 2005, 03:03:56 PM »

Hi Gary,

Thanks for the help. Is there any way that I can get a copy of the MSEA plans with more readable print? I went to the MSEA site but didn't see them anywhere.

GaryGary · « **Reply #11 on:** November 02, 2005, 06:37:16 PM »

Hi,

I'll see if I can't get a better scan up -- give me a couple days.

I'll put them at the same link I listed before.

Gary

GaryGary · « **Reply #12 on:** November 02, 2005, 07:40:06 PM »

Hi,

I rescanned them with higer resolution and saved them as image pdf files. They seem pretty readable to me now.

They are on this page:

http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm

The specific links are:

MSEA batch heater: http://www.builditsolar.com/Projects/WaterHeating/MSBatch.pdf

MSEA closed loop heater: http://www.builditsolar.com/Projects/WaterHeating/MSClosedLoop.pdf

These plans appeared in a publication that the MSEA did called: The Maine Solar Primer Edition 2". With Richard Komp's permission I scanned some of the more interesting stuff and put it on BuildItSolar. You might still be able to get a hardcopy of the Primer by contacting them at: sunwatt@juno.com

Richard can also answer any detailed questions you might have about the collectors, as he is one of the designers.

Good Luck!

Gary

Propwash · « **Reply #13 on:** November 02, 2005, 08:12:30 PM »

Thanks Gary!!

hvirtane · « **Reply #14 on:** November 03, 2005, 01:07:25 PM »

If the wind resources are good

in your area, I think that you

should just build a big wind turbine

for heating. Small 12' diameter

wind machines will make really

little energy, but if your machine

has got 10 m diameter wind rotor,

then the rated power at 10 m/s

wind speed is already 15 kW.

- Hannu

Propwash · « **Reply #15 on:** November 03, 2005, 03:11:01 PM »

I like that more power theory but I thought I would cut my teeth on the 12' model. Thats about as large as I can go and still be able to use materials laying around the yard to build it. It looks like it may take a while to make these devices pay for themselves so the less money invested the quicker the payoff. More of that backwards thinking!

hvirtane · « **Reply #16 on:** November 04, 2005, 04:07:44 PM »

If you'll follow the course

of most people here, the costly

things are the permanent magnets

for the generator. Other things for

for example 'OP' 17 feet wind generator

cost just about the same as for

a 12 feet wind generator. And I see no

reason, why you couldn't expand the general

layout to even bigger, let's say 7,5 m

diameter rotor.

I think that it might be

cheaper to make the generator for

that kind of big machine by using

some kind of induction engine conversion.

Then you would need less magnets.

Another kind of cheap system might have

a gearbox and an induction engine

used as it is as the generator.

On the other hand to make the system

with a good efficiency you would need

some kind of system to control

the load according to the wind speed

and the power available from the generator.

- Hannu

Propwash · « **Reply #17 on:** November 04, 2005, 06:32:45 PM »

Fuel for thought Hannu! I found the magnets and wire for a 17' rig to be about twice the price of a 12' rig so thats where I drew the line. I would assume the tower would have to be heavier also. I have a whole junkyard full of outboard motors that have as high as 40 amp charging systems on them. They have a very similar setup under the flywheel as the wind turbines are using only on a smaller scale. I was going to gear one of these up to turn fast enough to charge off from blades but was dicouraged by the 50% power loss that takes place when using gears and or pulleys(at least this is what I have been reading). I figured I wouldn't try and reinvent the turbine but take a design that works and learn from it. I live on a coastal island in Maine and our winds are very violent and gusty. I think a 12 footer will make all the mess that I want to clean up after a Northeasta comes through.

I think your gearbox idea may solve some of the problems that I have been reading about with blade stall and so on. You could shift her down in lighter winds and upshift in heavier winds or visa versa. Thats what I like about this site, there is no shortage of ideas on here. Thanks Hannu!

Tyler883 · « **Reply #18 on:** November 06, 2005, 08:52:01 AM »

I like your general approach, directing all of your wind power needs towards the creation of hot water would save you alot of the setup and ongoing costs of storage batteries, chargers,etc. Even though a couple hundred watts of wind power isn't going to amount to alot of hot water, I like the simplicity of your system.

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Author Topic: solar water heaters (Read 3432 times)