vacuum tube compact solar water heater Spain

[cssolar]

Hi, I have vacuum tube solar water heating on my house in Spain, and it works great !!
in fact I was so impressed that I now import and sell them here.

I have found the best type for the hot climate combined with poor water quality to be the indirect pre heat type.

The main reasons are.

1 vacuum tubes will provide hot water nearly all year round

2 lower cost than split systems

3 can provide hot water at mains pressure, not gravity feed

4 main tank is vented so if the system over heats, steam and boiling water can escape

5 in kit form for easy assembly at point of use

6 water in tubes provides extra capacity

7 dose not rely on a pressure relive valve to protect the main tank, which can fail due to poor water quality calcium build ups

8 dose not require a boost pump for pressure, as is normally required on a non pressure gravity feed unit

Dose any body use this type of swh in their area, or what is your preferred type and why ?

Tony cssolar

[russ]

Hi Tony - Welcome to Solar Panel Talk!

Looking forward to your continuing participation.

Russ

[cssolar]

Swh

Hi Russ,

Thanks for the welcome,

I see you are in Turkey, I hear solar is very popular there !


Cheers Tony

[russ]

Hi Tony,

Many residential solar water water heating systems here - practically zero solar PV. No incentives, subsidies or FITs available and everything costs extra due to import duties.

Russ

[cssolar]

Swh

Hi Russ,

Its a shame if import duties were lower then more people would consider solar energy.

We have the same problem here, my import costs are almost 100% more than the cost of the swhs from the factory !!

Solar thermal is little used here as is pv its such a shame with all the free solar energy we receive.

I wonder if governments worry about all the tax they will loose on fuel !!!! if too many people use alternatives

Regards Tony

[cssolar]

Hi All

Have not been on the forum for a while , just like to say my non pressure Chinese swhs are performing well , fitted them back in 2008 , best move I made , very simple thermosiphon low tech units
with a controller / solenoid fill valve and auto boost ( power shower type pump for pressure )

Cheers Tony

[sanramon]

Hi CSSOLAR y bienvenidos.,
Here in Costa Rica the only systems in use that I have seen are the water-in-glass evacuated tube types as you described - Chinese made of course. The company that supplied mine in 2012 says they installed 30 units in the past 2 years alone. I was one of the earliest adopters of their product.

All 8 of your points are exactly correct for this tropical area. Haven't found any negatives for this type of unit yet, other than the installer. At first he installed with the tank tilted lower to the fill/expansion tank/vent. This caused steam build up in the storage tank to force good hot water out regularly. After contacting the company, the installer adjusted the tank correctly. And, because of an earthquake, the tank nearly collapsed several years ago. This time I realigned it and added braces. Now, all is well. Our 20 tube, 200 liter unit has supplied 4 adults and 3 teenage girls with hot water for a whole week without electricity.

[cssolar]

Hi CSSOLAR y bienvenidos.,
Here in Costa Rica the only systems in use that I have seen are the water-in-glass evacuated tube types as you described - Chinese made of course. The company that supplied mine in 2012 says they installed 30 units in the past 2 years alone. I was one of the earliest adopters of their product.

All 8 of your points are exactly correct for this tropical area. Haven't found any negatives for this type of unit yet, other than the installer. At first he installed with the tank tilted lower to the fill/expansion tank/vent. This caused steam build up in the storage tank to force good hot water out regularly. After contacting the company, the installer adjusted the tank correctly. And, because of an earthquake, the tank nearly collapsed several years ago. This time I realigned it and added braces. Now, all is well. Our 20 tube, 200 liter unit has supplied 4 adults and 3 teenage girls with hot water for a whole week without electricity.

Hola Sanramon
Glad to hear your non non swh is working well , it is strange many people dont like the water in tube type , But as you have not come across any problems , in my years of dealing with Chinese swhs I found the vacuum tubes very strong , only on had one occasion of broken tubes and that was down to hail as big as golf balls ! it even smashed roof tiles .

We also have made use of our swh in electric cuts , because our main house water is pumped from a storage pump , we can still use the head of water stored in the solar tanks on the roof by gravity feed

Yes Poor installation can be a problem , venting is very important !! do you fill just by the assistant ( small top up / expansion tank ) or do you use a controller with level sensor and fill valve ?

In China these stand alone units are very popular and cover many roof tops ,

Cheers Tony

[sanramon]

Hi Tony.
The supplier here in CR says the tubes are strong enough to survive 1" (25mm) hail stones. But hail here is VERY rare, so other than bad handling or falling tree branches these tubes should stand up very well.

Our system uses only the filler/vent tank to keep the main storage tank full by using a floating ball valve, and is well vented. The serpentine inside uses mains water pressure. Strangely, the suppliers (several different ones) here do not install temperature/pressure relief valves in the serpentine circuit. I asked if it was needed and was assured it is not. I don't know why not here when I read on this forum so many people insist such a valve MUST be installed.

We have no electronic controllers, assistant pumps or other equipment in our system - simply, sun = hot water.

[cssolar]

Hi Tony.
The supplier here in CR says the tubes are strong enough to survive 1" (25mm) hail stones. But hail here is VERY rare, so other than bad handling or falling tree branches these tubes should stand up very well.

Our system uses only the filler/vent tank to keep the main storage tank full by using a floating ball valve, and is well vented. The serpentine inside uses mains water pressure. Strangely, the suppliers (several different ones) here do not install temperature/pressure relief valves in the serpentine circuit. I asked if it was needed and was assured it is not. I don't know why not here when I read on this forum so many people insist such a valve MUST be installed.

We have no electronic controllers, assistant pumps or other equipment in our system - simply, sun = hot water.

Hi Sanramon

Yes I think 25mm is the maximum the tubes can take ,
I see you are using a pre heat coil in tank type , that is a good choice , no problems with over pressure and you can have good water pressure via the copper coil heat exchanger .

I tell my clients to fit a safety valve on cold inlet of the coil ( same type as is fitted to an electrical water cylinder boiler ) , but I guess if you have been using your swh for many years with no problem , why worry !

Its nice to keep the system simple , less to go wrong , I have a direct feed non pressure swh ( like yours but with out the coil ) so the controller is useful for me , for example if I have half tank of 54 c water but weather is bad I can program it not to fill until the temp reaches 65c , the only problem with non pressure swh is I need a boost pump to get good pressure in the house .

I do have two pre heat units on my roof as well , one powers underfloor heating ,the other hot air heating

The strange thing here is hardly any one uses this free energy , I cant understand why , do many people use solar water heating in the Costa Rica

Cheers

Tony

[sanramon]

Hi Tony, Wow, you have gone all solar! I have gone half way - have solar pool heat (for 7 years) and installed solar panels and a DC powered swimming pool pump 2 years ago. Cut power costs to half or less. Solar water heater 4 years ago.

I am curious, when you refer to this:

"I see you are using a pre heat coil in tank type , that is a good choice , no problems with over pressure and you can have good water pressure via the copper coil heat exchanger ."


why you call it a pre-heat coil in tank.? As I understand it, this is the heat exchanger for the cold water taking heat from the 200 litres stored in the main tank. I don't think it "pre-heats" anything. The water from the coil is the water we use.

But I see from your explanation why you need the controller and boost pump.

Use of solar here in CR is still very new. The power company ran a 2 year pilot program for grid-tie power generation, and just this month put it into general use. Only a few companies have taken up this offer and fewer homes. As for water, still not widely used - I think mainly due to economic level. Today's price to install a 20 tube, 200 liter unit is US$ 1,404. Average gross national income in CR is US$ 6,810 (2013 figure).

[cssolar]

Hi Sanramon ( we have a street in the village with that name too ! )

Sorry I used the name pre heat for your type of swh because the Chinese factories use that name ( but you are right it dose not have to pre heat anything , strange why China adopted that name ? )

I guess indirect swh would be better .

How do you find your solar pool pump set up is it powerful enough ? what sort of collectors do you use to heat it with ? , I have one pre heat ( indirect ) unit heating my pool , I just pump some of the water through the coil , I know its not really correct to pass pool water through copper pipe but the unit was free for me so have nothing to loose . but to be honest it dosnt make much difference to the temperature , think I need about 4 to 6 panels

Here in Spain there is little incentive to use solar for PV as the government has been talking about taxing the sun ,,!! what will they tax next , I wonder !

Yes I guess the initial cost of installation with solar hot water is a problem , as you say it is a big part of the average income ,

I have found swhs are quite cheap in China and the main cost is import duty , It is within governments power to reduce the duty to promote the use of solar water heating , but I guess they enjoy the tax more !

Tony

[sanramon]

Hi Tony,
I know this isn't the right forum to discus PV powered pool pumps, but I cannot find any way to Private Message you.

So, our pool pump is a Lorentz of Germany, model PS600-cs-17, rated at 600w at 10A. It is driven by a Lorentz controller PS600, Max voltage >68, Open Circuit Voltage max 150VDC, output 10-60VDC, PWM 3 phase, normal power 700W. I don't know the model or rating of the 3 solar panels on the roof. Open circuit I measures 72VDC. In full sunlight the pump runs at 2000rpm. More than enough for the sand filter and 7 rooftop pool heating panels 3ft X 10ft. Without the thermostat for the diverter valve set right, pool temp gets over 34*C for a 25,000 litre pool.

As I understand pool heating, the objective is to heat a large volume of water by a small difference in temperature - rather than DHW systems that heat a small volume of water to a much higher temperature.

As far as I know, here in CR, duty or sales tax or whatever is applied - is lower on PV systems, and perhaps on DHW systems - but I can't prove that.
Again interestingly here, the major power company (nationalized), and for the first 1/4 of this year ran on over 97% renewable energy. That includes hydro, geothermal, wind, and to a very small degree biomass and solar.