Tuesday, February 9, 2010

Hey dude

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For D Day at ABC Wednesday, let's take the Hebrew word dood.


A dood shemesh is a solar water heater.
Some 90% of Israeli families have one on their roof.
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The first two photos are not representative because these tanks are sitting on the ground, next to their house. (Well, actually it is a converted chicken house, with a roof apparently not strong enough for a dood on top.) But it is a good chance to show you a dood up close.
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Typical domestic units consist of a 150 liter insulated storage tank and a 2 square meter flat panel. The black collector panel collects solar radiation, heats the water, and passes it to storage in a pumpless, gravity-driven loop.

Convection carries colder water from the bottom of the tank into the collector and hot water rises to the upper intake on the tank.

After a few hours of good Israeli sunshine, you just open your taps and out comes near-boiling water!

If the sun hides for a few days (which happens only in winter), set the timer or flip the switch to run the immersion heater built into the tank for half an hour before you want a shower.

The ubiquitous dood shemesh is found on apartment building roofs,

on buildings in Jerusalem's Old City,


on Vatican-property roofs in East Jerusalem,
and on Bedouin village houses in the desert.
In short, EVERYWHERE.

On slanting roofs, the dood is often put in a horizontal fashion.
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Good system to let the sun do the work, eh? Saving fuel, saving money.
Would it, or does it, work in your country?
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In 2005 Spain became the second country (after Israel) to require solar water heaters by law.
And in 2010 Hawaii will require all new houses to have one!
How do you say dood shemesh in Hawaiian?
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29 comments:

Roger Owen Green said...

We need to do that more in the US (besides Hawaii.) Some places DEFINITELY could make it work. It's the initial cost to retrofit that makes it difficult to do on older housing units. But new construction could be a market.

On behalf of the ABC Wednesday team, thank you!

Linda said...

Interesting. I learned something new.

Spiderdama said...

It`s good to let the sun do the work!:-) It would not work here north..
Great D and photos!
Shalom!

Cloudia said...

90% !

We in Hawaii have a lot to learn from Israel. ORMAT is harvesting power from the Big Island's volcano!


ShAloha, DiNa

Comfort Spiral

Johnny Nutcase said...

Thumbs up for solar power!! Great post with a bunch of info and I like the pictures too.

Leslie: said...

Because of your climate, this makes such good sense. Wouldn't work here, though, as half our year we're covered by clouds.

jeannette stgermain said...

Making use of natural resources - how handy! I haven't seen these in the USA (yet).

gigihawaii said...

I have solar water heating at home in Honolulu. The panels are on top of the roof, while the actual heater is in a shed in the patio. The panels on the roof will need to be replaced eventually, as they are getting rusty.

Ann said...

90% that's impressive and something we should be doing.

Katie said...

Normally Florida has enough sun to heat up anything.

Life with Kaishon said...

I love the architecture of your city! I visited Jerusalem when I was in college. I have many wonderful memories of that trip. We floated in the dead sea. That was amazing. And we saw the wailing wall. I loved it!

Sara said...

Fascinating! That's a new look...I don't remember that in 1995. We could certainly do here in Southern California too. Some people do have solar panels on their roofs...but I've not seen the cylindrical part.

Tumblewords: said...

There's sun here less than 1/2 a year so not much solar going on except for marginal personal use. I'd love something of that order but I'm finding, too, that cost is prohibitive.

Tarun Mitra said...

Wow...In India they are bit costly but yet gaining some momentum ..

Jama said...

I love reading your blog, it exposes me to the Hebrew language.

Pietro said...

This is really interesting, Dina. We have not solar water heater in our houses. I've never seen them here. Very beautiful views of the town!

Robin said...

Yup, they're everywhere. I'm really looking forward to the end of winter so I can depend on mine all the time and not have to use the supplemental electric heater on overcast days - I never remember to turn the timer on on time so that I can have a hot shower when I want it!

Jilly said...

This is to be commended and strangely, with all the sunshine here (normally!) we don't see many solar panels. A good lesson to us.

Tahnks so much for the blog birthday wishes, Dina.

Jedediah said...

I didn't know that they were so popular in Israel, but it makes sense. In Germany, they are pretty rare, but people do use them, especially when building a new house. You wouldn't be able to rely on them alone, but it does save energy, especially with the hot and sunny summers we've had these past few years.

Nicole said...

They look a bit odd on those rooftops, but they make up in points with the smartness.
You would think they would do the same here in Egypt, no?
Sigh....

Eki said...

Now that's an environmentally-friendly practice, Dina!

I love it.

I think we should have it here as the sun shines almost all year round. It would safe a lot of fuel energies.

Kate said...

90%...that's a huge number! Is it a consequence of the law; I suppose it is. I'd be curious to know what the percentage was before the law was passed. Would be a good idea for the entire USA, I think.

RuneE said...

I have seen something approaching this in Greece, but I would be Dumb if I thought it would work here ...

PS Among other things I took my Ph.D. here and was also a student before those eight years.

Sheila said...

You do need some access to sun. :( Otherwise I'd be all in favour. I hear "they" are developing solar or photovoltaic cells which can function well in lower light settings.

VP said...

Thank you for your extensive update on the dood. These devices were already everywhere in the early 90s and I am impressed by the fact that at here, at home, they are still nowhere to be seen.

Louis la Vache said...

«Louis» read both this post and the one above it with great interest. Not surprisingly, this type of installation is rare in the U.S.

Reader Wil said...

Solar energy is excellent! I have solar panels on my roof and they produce a lot of energy. Very great post, Dina! BTW "dood"in Dutch means dead and is pronounced as "ou"in "dough".

Pasadena Adjacent said...

I want to go in and design those atop the roof to look like spools of thread. The clothes lines could be considered the thread and the clothing brings the concept together.

thinking out loud

Dick said...

I don't think it will work here as good as in your country. Maybe in the summer it will give enough hot water but as you know we need more energy during the winter but the sun is not strong enough then.