solar water heating in spain

 Compact vacuum tube solar water heaters ( the type where the tank and collector tubes are joint an one unit  ) are very simple.

I will try and explain how the type that I import and sell works.

the type I have are known as pre heat units the main parts are-

1 vacuum tubes

2 hot water tank

3 copper coil heat exhanger 

4 top up tank

5 frame

The vacuum tubes are the parts that collect the energy, they are similar in construction to a thermos flask interior ie one glass tube inside another with a vacuum between the two, Then inner tube has a special coating that absorbes the solar energy and heats the water inside, the vacuum acts as an insulator , not letting heat escape once inside.

As the water in the tubes gets heated by the sun it becomes lighter and rises into the hot water tank, cooler heavier water sinks to the lowest part of the vacuum tube, all day this circulation continues heating the water up ( in the summer can easily reach boiling point )

This hot water stored in the tank is not used directly ( dose not go to the taps ) the reason for this is that it is at very low pressure, because the tank is open ( has an over flow vent ) If the water were to boil steam and hot water would be dumped, to maintain the water level in the hot water tank there is a small top up tank with a float valve  ( It could be compared with how a cold water storage tank works except the water is hot )

Inside the hot water  tank there is a copper coil heat exchanger , this is where we get the hot water to be used . 

When a hot tap is opened cold water enters the copper coil and is heated then returns to the tap for use.

Very simple !!

 After doing some reserch, I have found that some dish washers can accept pre heated water.

Today I have plumbed my dish washer into my solar hot water feed, the dish washer book says that water up to 60 degrese if fine, 

I have fitted a thermostatic mixing valve to ensure the water entering the dish washer is not to hot.

I am sure that I will notice a drop in my electric bill as the dish washer will now use a lot less energy !!

Tony cssolar

www.cssolar.es

Here in Spain we get lots of  sushine of most of the year, which makes it ideal for solar, a common problem with vacuum tube solar water heaters can be over heating in the summer.

With high pressure units it is very important to maintain the pressure relife valve, so to avoid damage if it becomes blocked and fails.

Vented units ( pre heat indirect and non pressure direct systems) do not suffer from this problem because when the water boils it will escape from the over flow vent .

It is important to remember that any unit left for a long period and let to over heat every day is not a good thing and with time will result in damage.

Vacuum tubes are very powefull and it is best to use there types of  solar water heaters on a daily basis as this will have a cooling efect and prevent damage, However if you find your swh over heating in the summer and it is in constant use , its performance can be easily reduced by blocking out the sun from some of the tubes, this can easily be done by sticking electrical insulation tape strips to the front of them . In the winter it can be easily removed to get the full performance back.

If you are going away on holiday for over a week it is important to cover all of the tubes ( in effect turning the power off as you would do with any other appliance. eg, you would not go on holiday and leave the gas fire on !!)

first find a suitable position, facing the sun at mid day is good, vacuum tube units come in kit form so it is not to hard to get the bits up to where you need them, first assemble the frame and fit it down, if fitting to a flat roof or terrace it is best to mount the unit on four patio slabs to aviod causing any leaks in the roof deck. then fit the tank ( 4 bolts ) next fit the tubes, it is very important to pre fill the tubes with water in the shade before fitting them because filling a hot tube with cold water can cause it to shatter !  smear some olive oil on the end of the tubes and on the tank seals and insert with a twisting action.

run pipe work from existing boiler up to the solar water heater feed the cold in and return the hot back, if you have an electrical cylinder a good way to install is to pre heat, so feed the hot return from the solar water heater into the cold inlet of the cylinder,

Now the electrical cylinder will be fed with pre heater hot water from the swh so it will make the system automatic as it will only cut in when required ie in poor weather or if no water has been drawn for a long period of time.

It is possible to use the solar hot water direct but it is advisable to leave your existing boiler for back up , a simple change over system can be made using two valves

Fitting is not to complicated and self fitting will save a lot of money and reduce the pay back time!!

Solar water heating  works well here in Spain and will reduce bills!!

Hi every body, my name is Tony I live in a small village called Agost which is just inland of Alicante, When I arrived in 2003 the first thing I done was starting to renovate the old house we bought in the Campo of Agost, I soon realised that is was becoming a bit of a money pit ! so I decided to go out and do some building work with a friend, Due to my friends poor health I started to work on my own ( leagaly self employed ) , work was ok up to the begining of the crisis, then the building work almost dried up, so I decided to look for a different way to earn a living.

That is when I decided to go into solar water heating, The sunshine is free and we get a lot of it here so it seened like a good idea to give it a go !

FIRST I wanted to see if solar water heating was really any good !

So I bought a solar water heater off the internet, then my problems started , there were no instructions of how to assemble or fit it , only a hand drawn sketch, I figured out how to assemble the unit and then fixed it to my roof , then plumbed it in as to the sketch. Then when I started to fill the unit for the first time I learnt my frist important thing about vacuum tubes and that was dont fill them with cold water on a sunny day because they can shatter.

After getting 2 replacement tubes and this time pre filling them in the shade I started filling the unit with water , when it was full there were more problems water was leaking from some of the seals where the tubed go into the tank.

After contacting the manufacturer I found out that the type of solar water heater I had was a non pressure type and the importers instalation sketch was tolaly wrong ! as it could not have a direct mains pressure water feed .

So i went to the plumbers merchant and got stuff to make my own small top up tank using a piece of capped soil pipe and a toilet float valve !

Now the main tank could fill its self up automaticly via the float valve .

The water was really hot ! but there was another problem - poor preasure ! because the hot water was only coming down at gravity pressure it was ok for the sink but not any good for showering.

So the next  modification was to fit an automatic booster pump to give the hot water more pressure !

In the end the system worked and I proved that it was worth having a solar water heater.

After more reserch I found there were better units that do not rely on gravity so now I import and sell them myself.

I do belive in solar water heating and am sure that it will become more popular here in Spain expecialy as it is not to complicated to self fit .