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I am planning to put a solar water heater behind my house in a sunny area about two meters above the ground and away from any shade from the roof of the house. The model I am looking at has a 150 liter tank and has 15 glass vacuum thermo-syphon tubes. The system is all stainless steel and is non pressurized, has a non electric automatic filling valve that keeps the tank full without overflowing the tank. The system comes with a 15 year guarantee. I haven't bought it yet but I would really like to know how many others there are out there in Thailand that are interested in this option for heating water. Anyone with experience good or bad, I would love to hear your comments. This heater comes with an option to add an electric heating resistance with a built in thermostat which can be used on cloudy or rainy days. I think is it only 1500 watt but it only has to heat a 150 liter tank. This unit is built in China and I am not to sure about the quality. My biggest concern is having a hail storm break the glass tubes or cold water entering the system when it is empty and in bright sunlight which could break the glass with thermal shock. The high cost of this type of heater is mainly tied up in the vacuum tubes that are using the vacuum to create a perfect insulator around the heating pipes surrounded by the glass tube. This way the insulated tank plus the insulated by vacuum glass tubes will keep the water hot on a very cold night.

 

Image of water heater from Google:   https://images.app.goo.gl/UR7XJAhTzTPqDgzJ7

 

My plan is to pump the water from the solar heater with a dedicated pressure pump rated at 90 degrees C. Another identical pump will draw water from the 1000 liter cold water storage tank and the water under pump pressure will mix with a thermostatic mixing valve to reduce the temperature from hopefully 85 degrees to 50 degrees C. I have already bought the pumps, thermostat and the fittings so I am pretty committed to the solar idea. I have used PP-R piping for the whole hot water piping system. I am using a special grade of 1" PP-R pipe rated at maximum 95 degrees going through it from the solar heater to the pump inlet. Then on the discharge side galvanized steel to the mixing valve. After the mixing valve the pipe reduces to 3/4" rated at 60 degrees C. and feeds the kitchen, the two showers, the bathtub and under the concrete driveway to the small bungalow by the pond for a hot shower there. I am hoping to get the water in the tank up to about 85 degrees by the end of the afternoon and my guess is that I will be able to add another 100 liters of cold water through the mixing valve to get the temperature down to 50 degrees.  This should give me enough hot water to fill the bath tub on a sunny day. The main reason I went with solar is because I have only a 15 (45) amp single phase meter and I have 3 x 12,000 btu double inverter aircons in the house, 1x 10,000 btu standard aircon in the garage and a 9000 btu double inverter aircon in the bungalow. There is a 3 Kw submersible deep well pump and the two 750 watt water pumps as shown in the photo. I think there is not enough reserve amps to power a 10 Kw water heater as required in the Chiang Khan winters. I have a 3.5 Kw single use water heater in one shower now and can get only a trickle of hot water out of it now that the well water is getting cold and it is only the first day of December! So solar water heater it is out of necessity! Please comment good or bad, I will listen and heed the good advice given. 42425721_hotandcoldwaterpumpsetup.jpg.01b694978ba5b9b78b5f2ef6cf4d8722.jpg

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Not here but in Turkey most houses have a large solar panel and 200 litre tank on the roof from memory it's a simple setup without pumps gravity fed with a ballcock in the tank I remember it also had a blow off valve when the tank reached boiling and often went off in summer something you wish to consider in your system as it's even hotter here also in the tank was an immersion element for winter use though temps never get low enough for that here good luck 🤔  

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7 hours ago, thaisail said:

Please comment good or bad, I will listen and heed the good advice given.

The solar unit, if it is well made with good QC, is designed for countries with generally lower temperatures than usual in the majority of Thailand, it’s likely to function well enough.


So your biggest problems will be getting your water too hot, so as long as you have engineered your system to allow for that and can flow sufficient water through to avoid boiling the water and so getting a pressure explosion as the water to steam  expansion ratio is 1,700 X so unless your expansion strategy can cope with that you have to be certain you are  never ever going to boil the water.

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7 hours ago, sometimewoodworker said:

The solar unit, if it is well made with good QC, is designed for countries with generally lower temperatures than usual in the majority of Thailand, it’s likely to function well enough.


So your biggest problems will be getting your water too hot, so as long as you have engineered your system to allow for that and can flow sufficient water through to avoid boiling the water and so getting a pressure explosion as the water to steam  expansion ratio is 1,700 X so unless your expansion strategy can cope with that you have to be certain you are  never ever going to boil the water.

The tank is vented so there is no risk of steam pressure building up. There are some of these units installed in Phuket and in the late afternoon steam can be seen coming from the vents. The big issue for me is the 1" PP-R pipe that supplies that hot water around 10 meters from the heater to the pressure pump. This pipe is rated for maximum 95 degrees C. I hope the pipe manufacturer has built in a factor of safety but it will be better to find a safety system that will release a spring loaded cover in the event of too high temperature to block the sun from reaching the tubes. The pump is rated for maximum 90 degrees but I feel confident that the water will cool in the underground pipe enough to protect the pump. I am still working on the design for the spring loaded safety cover so if there are any other steam engineers out their with ideas, I am ready to listen!

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21 hours ago, sammieuk1 said:

Not here but in Turkey most houses have a large solar panel and 200 litre tank on the roof from memory it's a simple setup without pumps gravity fed with a ballcock in the tank I remember it also had a blow off valve when the tank reached boiling and often went off in summer something you wish to consider in your system as it's even hotter here also in the tank was an immersion element for winter use though temps never get low enough for that here good luck 🤔  

My original design was similar to what you describe in Turkey. My plan was to install the solar heater with the 150 liter tank on the roof above the bathroom. I would have filled the solar heater with a modern version of a ball cock from the cold water pressurized well pump. But the same small tank with the ball cock would also supply cold water by gravity to mixing valve at the shower. This way the hot water head pressure would be identical to the cold water pressure making it very easy to mix the hot and cold water to create an steady comfortable water temperature.  However, my building contractor informed me that there was too much weight in the solar heater system and the roof he built would not support the weight of the solar heater when full of water. So. I decided to go with plan B and mount the water heater about 2 meters above the ground and use two identical automatic pressure pumps that kick in at 1. 3 bar and dropout at 2 bar. I am hoping that the two pumps will not fight each other and create an alternating hot and cold water shower. Everything will depend on how quick acting the thermostatic mixing valve will function. I hope it will regulate the  hot water water at a stable temperature, otherwise it is back to the drawing board! As for the steam situation, I am still working on a design that will put shade on the water heater before the water in the tank starts to boil. 

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58 minutes ago, worgeordie said:

We have had a SolaHart system installed on our roof for the last

30 years, I am sure it has paid for itself, and just having hot water

to all the sinks,showers and bath it's well worth it.

 

It does not have any pump supplying water to it,just fills by water pressure

or auxiliary heating ,the water reaches scalding in summer,there is usually

about 3-5 days not consecutive,in the winter where it does not get hot.

 

Anyone building a new house i would advise installing a system.

regards worgeordie

 

I checked out the Solahart website and if the ones shown on that site are the same as the 30 year old model, it looks really good. But I fear the price of a system like that for me would be prohibitive. Please can you give me some idea of your cost to buy the system 30 years ago and how much maintenance and cleaning was required since then? 

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1 hour ago, worgeordie said:

We have had a SolaHart system installed on our roof for the last

30 years, I am sure it has paid for itself, and just having hot water

to all the sinks,showers and bath it's well worth it.

 

It does not have any pump supplying water to it,just fills by water pressure

or auxiliary heating ,the water reaches scalding in summer,there is usually

about 3-5 days not consecutive,in the winter where it does not get hot.

 

Anyone building a new house i would advise installing a system.

regards worgeordie

 

Yes Australian designed I had one for donkey ages I don't know the cost in Thailand

but in Australia they are dirt cheap and so are the solar panels

  • Haha 1
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7 hours ago, thaisail said:

I checked out the Solahart website and if the ones shown on that site are the same as the 30 year old model, it looks really good. But I fear the price of a system like that for me would be prohibitive. Please can you give me some idea of your cost to buy the system 30 years ago and how much maintenance and cleaning was required since then? 

I cannot remember how much it was ,either 25K or 50K*, at the time it did seem

expensive, but turned out to be well worth it ,hot water throughout the house,

no risk of electric shock,we have rental properties and over the years have had

to change quite a few hot water shower units.Solahart only came once,only

thing they changed was a pressure valve.

*lot more expensive now obviously, but with returns in the banks,better to invest

your money in a solar water heater,if you are here for the long term.

regards Worgeordie

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16 hours ago, worgeordie said:

I cannot remember how much it was ,either 25K or 50K*, at the time it did seem

expensive, but turned out to be well worth it ,hot water throughout the house,

no risk of electric shock,we have rental properties and over the years have had

to change quite a few hot water shower units.Solahart only came once,only

thing they changed was a pressure valve.

*lot more expensive now obviously, but with returns in the banks,better to invest

your money in a solar water heater,if you are here for the long term.

regards Worgeordie

After spending what we did to build this house in Chiang Khan, we just don't have enough funds left over for that much of an investment. How ever, there are some newer technologies coming out along with some much lower prices from China. I am still researching to find an affordable solution. Right now the best option I have found as been this one.

 

SFD结构图

 

SFD.jpg

 

热水器特点图

SFVA.jpg

 

 

 

I really like the simplicity and the idea of passing pressurized cold water through the coil of copper piping inside the tank so that the cold water pressure and the hot water pressure will be identical. I think the cost of this system landed in Bangkok could be less than 10,000 baht and this will give me a good project to keep my engineering skills sharpened to assemble and do the installation. 

 

 

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Yes, I would go with anything that could provide the hot water to your

house,basically for free, If you are handy and can fix things,there is

not much to go wrong with them anyway. Good luck

regards Worgeordie

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Another alternative would be to run a ground mounted storage hot water system and run the internal thermostat controlled element direct from 3 or 4 solar panels.

I'd tend towards a 250 litre just for the not-so-sunny days.

Of couse you could always incorporate a changeover switch for manual heating off the mains should you think it necessary.

I'd tend to get a lecky to do that part though as you don't want mains supply backfeeding into your panels.

Seems to be done in a few places over here in Aus.

No pumps, no piping from the roof to the unit etc. etc.

Just a run of 4 sq mm cable.

Life span of the system would depend on your water quality.

As an example, the water on my brother's side of town is not so good and he has a replacement every 8 to 10 years.

If he checked the anode a bit more regularly he might squeeze a few more out of it though.

Whereas my systems tend to last anything up to 20 years.

I've seen one Rheemglass on tank water on a farm go for over 40 years.

Edited by bluejets
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4 minutes ago, bluejets said:

Another alternative would be to run a ground mounted storage hot water system and run the internal thermostat controlled element direct from 3 or 4 solar panels.

Seems to be done in a few places over here in Aus.

No pumps, no piping from the roof to the unit etc. etc.

Just a run of 4 sq mm cable.

 

I am toying with the idea of using solar panels to power a heat-pump water heater and use the cold air is generates to cool the top floor...

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Yes, I've seen those and there were quite a few installed maybe 10 years back. Part of all the greenies hike.

Never liked them from the beginning and most have since been ripped out and reverted to standard storage systems.

One downside was if it ever failed. (Or if you lived anywhere where the temperature dropped below 5 degrees C.......Just don't work then at all)

First one would naturally call a lecky.......he would come out, test for power and then leave after handing over a bill for a call (maybe $80 to $100)

Then a plumber was called in to check any valves etc....... same outcome and another bill for usually a lot more as plumbers here really sting.

So then a refrigeration mechanic would be called and he would check basic things and as the system manufacturers would not release any service details, he also would leave a bill.

Final approach was to a manufacturer recommended service person who would usually have a two day travel bill waiting before he even looked at the system

Usual conclusion was for a quote closely resembling the cost of the original system ( and the weren't cheap by any means)

Basically I wouldn't touch one with a forty foot pole. 😝  

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When working in Namibia, in Bushmanland, a few years back we would get an 8 x 4 piece of plywood, paint it black and lay it flat in the garden close to the outside shower.  On the plywood we would coil black plastic pipe, about 40 metres perhaps of 1/2 inch dia.  Connect incoming cold water to one end and after a day in the sun out came hot water from the other end.  Connected to a mixer tap at the shower head we had enough hot water for showers for my wife and I.  Water pressure came from a water tank 30 ft above ground filled from an artesian well through a solar powered pump.  Brings back good memories.

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