# Solar Water Heating



## neddie (Jun 11, 2012)

....If anyone has any experience of using solar heated water for space heating or to supplement electric heating of a geyser, i would appreciate any comments.

...In Uruguay where electricity is very expensive there are a number of expats who use it and thus save a bundle. A number of them also use wood stoves for space heating but wood is both plentiful and relatively cheap over there. I have noticed in some of the ads i have looked at of homes for sale in Spain that a few of the homes had wood stoves......is wood readily available (in Andalucia)?


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## Cazzy (Nov 23, 2008)

neddie said:


> ....If anyone has any experience of using solar heated water for space heating or to supplement electric heating of a geyser, i would appreciate any comments.
> 
> ...In Uruguay where electricity is very expensive there are a number of expats who use it and thus save a bundle. A number of them also use wood stoves for space heating but wood is both plentiful and relatively cheap over there. I have noticed in some of the ads i have looked at of homes for sale in Spain that a few of the homes had wood stoves......is wood readily available (in Andalucia)?


We have solar hot water and can use it about 46 weeks a year, it has an immersion heater in it in case there is no sun, but you rarely need it. Best thing we ever bought!!


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## NickZ (Jun 26, 2009)

He's asking about space heating not domestic hot water.


Best would be to use it with in floor heating. But that requires digging up the floor.

Second best baseboard radiators

Worse normal radiators.

It's doable but unless the OP is doing a major renovation job to begin with the cost of the setup might exceed the savings.

Smarter to upgrade the insulation etc first IMHO


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## snikpoh (Nov 19, 2007)

NickZ said:


> He's asking about space heating not domestic hot water.
> 
> 
> Best would be to use it with in floor heating. But that requires digging up the floor.
> ...


I agree but to upgrade the insulation in alot of Spanish houses is impossible.

For example, we have a 550 m2 villa with standard construction and the problems are;


The roof is concrete with 'valencian arches' - so no room for spray foam or insulation
The floors are concrete and tiles - no room for insulation without major reform.
The walls are standard bricks. That is, there is no cavity although the bricks are about 30cm thick. So, no room for insulation without major reform.
The windows are already UPVC double glazed.

What insulation could we do?


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## NickZ (Jun 26, 2009)

The walls are doable. 

External Wall Insulation | Homebuilding & Renovating

Some thing like that. 

Roof tiles? Can they be lifted and insulation sheets placed under them?

Obviously everything is easier if you're renovating. If the house is finished and in good condition the cost may make the savings minimal. That's often the problem. We end up spending 1000s trying to save pennies.


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## jimenato (Nov 21, 2009)

Incidentally, the OP is asking about water heating as well...



> or to supplement electric heating of a geyser


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## annfoto (Aug 19, 2012)

He is also asking about wood burners.


neddie said:


> ..... A number of them also use wood stoves for space heating but wood is both plentiful and relatively cheap over there. I have noticed in some of the ads i have looked at of homes for sale in Spain that a few of the homes had wood stoves......is wood readily available (in Andalucia)?


Wood burning stoves are very common in villas and country houses. 
Olive, almond, citrus and eucalyptus logs are all available in Andalucia but olive is the best and most popular. We get 2,000 kilos ( 2 tones) delivered at a time and it costs €240


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## neddie (Jun 11, 2012)

annfoto said:


> He is also asking about wood burners.
> 
> .....thank you.....i thought you all had forgotten
> 
> ...roughly how long would that amount of wood last under average winter conditions?


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## neddie (Jun 11, 2012)

Cazzy said:


> We have solar hot water and can use it about 46 weeks a year, it has an immersion heater in it in case there is no sun, but you rarely need it. Best thing we ever bought!!


...Interesting. Did you have it installed and do you know if the panels have vacuum tubes? Do you also use it for space heating or just for kitchen/bathroom?


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## baldilocks (Mar 7, 2010)

annfoto said:


> He is also asking about wood burners.
> 
> Wood burning stoves are very common in villas and country houses.
> Olive, almond, citrus and eucalyptus logs are all available in Andalucia but olive is the best and most popular. We get 2,000 kilos ( 2 tones) delivered at a time and it costs €240


Your wood is expensive, we usually only pay €80 per tonne and it is delivered and lugged down to our woodstore (two floors below delivery level) and stacked!

2tonnes usually lasts a whole winter but it all depends on the weather.


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## NickZ (Jun 26, 2009)

Is that dry and split?


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## baldilocks (Mar 7, 2010)

NickZ said:


> Is that dry and split?


Dry, cut to length and split if necessary but most olive wood is thinnings/prunings so not so thick as the trunks.


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## Twain (May 24, 2009)

baldilocks said:


> Your wood is expensive, we usually only pay €80 per tonne and it is delivered and lugged down to our woodstore (two floors below delivery level) and stacked!
> 
> 2tonnes usually lasts a whole winter but it all depends on the weather.


What are the rules in spain for sweeping chimneys?
An annual service or do it yourself?
If the price of wood is so low I have to rethink the use of water based underfloor heating.


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## baldilocks (Mar 7, 2010)

Twain said:


> What are the rules in spain for sweeping chimneys?
> An annual service or do it yourself?
> If the price of wood is so low I have to rethink the use of water based underfloor heating.


The price of leña (logs) varies according to where you are. Here in Jaén Province we have millions of olive trees (Jaén is the world's largest producer of olive oil - 62½%) so there is a lot of wood and it is therefore cheaper. Elsewhere it may be a different matter. We burn logs because, environmentally, it is better than the stuff being burnt out in the open and causing lots of pollution (the log burner burns at a higher temperature and there are fewer particulates produced).

However this doesn't produce hot water for which we use an instantaneous gas boiler. We are thinking of looking into a solar water heater to supplement the boiler during warmer months (cost of installation of solar panel v cost of bombonas - the portion down to water heating since we also cook by gas)


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## NickZ (Jun 26, 2009)

Twain said:


> If the price of wood is so low I have to rethink the use of water based underfloor heating.


Why? If wood is cheap it means you use wood. It doesn't mean you change the other elements. A thermostove will burn wood and heat the water for the radiators. Or in your case the floor.


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## baldilocks (Mar 7, 2010)

NickZ said:


> Why? If wood is cheap it means you use wood. It doesn't mean you change the other elements. A thermostove will burn wood and heat the water for the radiators. Or in your case the floor.


Why not combine the two and use solar when there is enough sun and wood when it is too cloudy, dull, and miserable (days specifically designed to remind Brits of home!).

The latest trend is to fire a burner with "pellets" or olive pips. 

What also has to be factored in is storage of the fuel. 2000 tonnes of logs takes up quite a bit of space (about 45 cubic metres) which is typically not next to the road, so it has to be lugged into the store (whole families get involved usually) and then brought bit by bit from the store to the stove. Pellets usually come in plastic bags and olive pips are delivered loose into your own storage hopper from where there is some sort of feed to the stove.


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## NickZ (Jun 26, 2009)

baldilocks said:


> Why not combine the two and use solar when there is enough sun and wood when it is too cloudy, dull, and miserable (days specifically designed to remind Brits of home!).
> .


Yes best. The solar can even preheat on those dull days so the wood needs to do less work.


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## baldilocks (Mar 7, 2010)

snikpoh said:


> I agree but to upgrade the insulation in alot of Spanish houses is impossible.
> 
> For example, we have a 550 m2 villa with standard construction and the problems are;
> 
> ...


The valencian arches are called bovedas (vaulting) and you can get preshaped polystyrene blocks that fit into the 'I' beams. 

Make sure that the external walls have a waterproof layer on the outside (possibly marble), we had water coming through the walls in 2009/10 winter - we now have "capa fina" on them.

We are considering putting thick layers of fibreglass/rockwool between the supporting beams, then boxing in when we have ours retiled in a couple of years.


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## baldilocks (Mar 7, 2010)

Re: Solar water heating

If you have a new build or have easy access to your bajos, you could consider storing heat in concrete blocks or if you are on rock or other stable strata - possibly using the ground for storing heat (geothermal storage).


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## montgo (Nov 6, 2011)

baldilocks said:


> Why not combine the two and use solar when there is enough sun and wood when it is too cloudy, dull, and miserable (days specifically designed to remind Brits of home!).
> 
> The latest trend is to fire a burner with "pellets" or olive pips.
> 
> What also has to be factored in is storage of the fuel. 2000 tonnes of logs takes up quite a bit of space (about 45 cubic metres) which is typically not next to the road, so it has to be lugged into the store (whole families get involved usually) and then brought bit by bit from the store to the stove. Pellets usually come in plastic bags and olive pips are delivered loose into your own storage hopper from where there is some sort of feed to the stove.


Where did the figure of '2000 tonne' come from, the earlier post mentioned 2000 kg, 
2 tonne?


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## jimenato (Nov 21, 2009)

montgo said:


> Where did the figure of '2000 tonne' come from, the earlier post mentioned 2000 kg,
> 2 tonne?




Yes - storage of a couple of tonnes can be a problem and it should also be indoor - dry storage. For that reason I usually pick up my own logs week by week in the car. That way you don't have to store so much and there is the added advantage that you can see what you're getting - the quality of delivered logs varies immensely I've found. It's the same price for small amounts as large amounts - 100 Euros per tonne here.


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## baldilocks (Mar 7, 2010)

montgo said:


> Where did the figure of '2000 tonne' come from, the earlier post mentioned 2000 kg,
> 2 tonne?


Inflation, a.k.a. a slip of the brain cells. When you've got plenty of them functioning, they work in unison but whe it gets down to just a few, they can't remember whose turn it is to work. It's a good job we haven't branched off into long- and short- tons.


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## Twain (May 24, 2009)

NickZ said:


> Why? If wood is cheap it means you use wood. It doesn't mean you change the other elements. A thermostove will burn wood and heat the water for the radiators. Or in your case the floor.


I was thinking about a fireplace in the livingroom.
But I guess I could use both.


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## NickZ (Jun 26, 2009)

An open fireplace is only a little better then burning money.

You can get a fireplace insert that will produce hotwater for your rads/in floor heating. It'll use less wood then an open fireplace.


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## Twain (May 24, 2009)

I was not thinking about an open one.

And I didn't know that I could use the same fireplace to heat water.
Will take a look at that. Thank you.


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## baldilocks (Mar 7, 2010)

Our logburner is a cassette type that has ducts which carry fanned warm air to the bedrooms above and the attic is heated passively by the warm air from the casing of the flue. Ours is a relatively inexpensive one but I'm sure there are others which will also heat water - we didn't go for one of that type because we would rather have the instantaneous gas boiler.


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## NickZ (Jun 26, 2009)

The hotwater ones can handle radiators .

This company for example but many others make similar things.

Heating Fireplaces, heating fireplace, heating fireplaces functioning 

They range from stand alone stoves to fireplace units.


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## MichaelJZA (Feb 8, 2013)

neddie said:


> ....If anyone has any experience of using solar heated water for space heating or to supplement electric heating of a geyser, i would appreciate any comments.
> 
> ...In Uruguay where electricity is very expensive there are a number of expats who use it and thus save a bundle. A number of them also use wood stoves for space heating but wood is both plentiful and relatively cheap over there. I have noticed in some of the ads i have looked at of homes for sale in Spain that a few of the homes had wood stoves......is wood readily available (in Andalucia)?


Hi Neddie,

I don't know if you ever got an adequate reply to this post. You can use solar heated water for space heating, but the best way to do that is with underfloor heating, which is hard to retro-fit and the good systems can be expensive. Getting the heat from outside on sunny days inside to heat the house is not easy. There is a system /SNIP/, which is basically a solar powered space heater - working by moving solar heated air into your house with a solar powered fan, and it is effective.

As to supplementing an electric geyser, in my opinion the best way is to set up a solar water heater as a pre-feed to your existing system. that way is there is enough solar heated water in the pre-feed system, it goes into your main system when you turn your tap on, and your element doesn't come on. If there isn't, on a rainy day for example, then your element works as normal. I think this is the best way to both save electricity costs and to have a reliable source of hot water when you need it.

Wood? It seems costly here to me, and is not really environmentally friendly.

You may want to ignore my post because I work for a solar company and therefore you may think I am biased. But It's the other way round. I work for a solar company because I know about this stuff...


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## baldilocks (Mar 7, 2010)

MichaelJZA said:


> Wood? It seems costly here to me, and is not really environmentally friendly.


Wood for a whole winter costs about €100-150 which si not expensive. As far as environmentally friendly - here we use olive wood which has to be burnt to eradicate pests and diseases. If it is burnt out on the campo there are lots of smoke particulates and you can't see from one side of the valley to the other but burnt at high temperature, the residues are completely burnt so no smoke particulates.


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## MichaelJZA (Feb 8, 2013)

I guess if you are burning wood anyway, you might as well heat your water with it. But it doesn't solve the problem of hot water when you don't want a fire.

I am not an expert on the relative benefits of burning olive wood or not, and I don't want to start a whole discussion about global warming, but it would seem to me that not burning wood is basically preferable to burning wood. If you can heat your house using sunlight, that must be better environmentally, surely?


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## NickZ (Jun 26, 2009)

Wood is a closed cycle. 

You grow a tree. Cut it down. Plant new tree. The net energy used is minimal. The way to think of it is the tree is a leafy solar plant.

Now this assumes a good burner and not an open fire but wood is considered renewable.


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## baldilocks (Mar 7, 2010)

MichaelJZA said:


> I guess if you are burning wood anyway, you might as well heat your water with it. But it doesn't solve the problem of hot water when you don't want a fire.
> 
> I am not an expert on the relative benefits of burning olive wood or not, and I don't want to start a whole discussion about global warming, but it would seem to me that not burning wood is basically preferable to burning wood. If you can heat your house using sunlight, that must be better environmentally, surely?


As I said, it has to be burnt anyway to destroy pests and diseases and we use a instantaneous gas water heater (multipoint) during the summer so we only heat the water as it is required rather than using an immersion heater to keep a tankful of water hot all the time.


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## ratzakli (May 20, 2012)

baldilocks said:


> Why not combine the two and use solar when there is enough sun and wood when it is too cloudy, dull, and miserable (days specifically designed to remind Brits of home!).


Also, the wood burner can give you a nice "homely" feeling on a cold winter evening - especially if it's got a glass front so you can see the flames flickering!


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## ratzakli (May 20, 2012)

baldilocks said:


> As I said, it has to be burnt anyway to destroy pests and diseases and we use a instantaneous gas water heater (multipoint) during the summer so we only heat the water as it is required rather than using an immersion heater to keep a tankful of water hot all the time.


I am looking into this for a possible move to Greece but, if you had solar panels, the heated water would circulate through the water storage tank and heat it that way so you would only need to switch the immersion element on during the worse few weeks of the year.

Of course, it all depends on the installation cost versus the savings you might make versus how long you hope to live for () to see if it would be worth it.


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