Solar water heater

[thaisail]

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. 

[sammieuk1]

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 ????  

[sometimewoodworker]

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.

[thaisail]

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!

[thaisail]

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. 

[worgeordie]

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

 

[thaisail]

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? 

[Meat Pie 47]

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

[worgeordie]

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

[thaisail]

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.

 

 

 

 

 

 

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. 

 

 

[worgeordie]

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

[bluejets]

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.

[Yellowtail]

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...

[bluejets]

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. ????  

[Geoffreyt]

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.

[Yellowtail]

34 minutes ago, Geoffreyt said:

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.

 

The hose must have been a lot bigger than 1/2", that's not much water...

[keithkarmann]

On 12/1/2020 at 12:18 AM, 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 ????  

In Greece we had some German solar systems with vacuum tubes and when they got too hot the panels had to be covered up.

[khunPer]

I put a solar water heater on my roof, with a hot water tank tank on the attic. This means that the water needs to circulate from tank to the top of the heating tubes, which is done by a Grundfos central heating-system circulation pump, designed to circulate up to boiling hot water, and use only up to 35 Watt for the models available in Thailand for around 6.5k baht (the new Danish models use little less power); however you might be able to find cheaper 100 W Grundfos circulation pumps online in for example Lazada.

 

The system cost was 40k baht 11 years ago and came with a useless cheap 350 Watt pump, the storage tank included an electric heater, which I don't use.

 

 

My circulation pump works with a daylight switch that switches the pump on when there is enough light, i.e. mainly usable Sun.

 

In hot periods the solar heated water is very hot and can last all night for showers – 4 bedrooms en suite – in not so sunny periods the system needs electric help.

 

I don't use the electric heater in the central hot water storage tank, as I designed my house with the normal small 3.5 kW electric instant shower-heaters, and the solar water heater as a pre-heater. For two reasons; so that there is instant hot water not to waste water running; and so that there will be hot water in cold/cloudy/rainy periods. The heaters run on 1/3 of heating power, 1/2 power in long periods without Sun, and can be switched off in summer months.

 

Heating up 200 liters of water in a central tank with electric power could be waste of energy, if you don't use a lot of hot water; when we don't have guests, we are only three people.

 

I've been very satisfied with the solar water heater system...????

 

 

[xtrnuno41]

The system is used to heat with solar heat by natural circulation. Cold water leaves to the pipes and warm water goes up again, all in same tank. On top of the tank you have the outlet for hot water and on bottom cold in.

You need solar time for heating, you cant go too fast by pumps and force a bigger flow.

As there is also an electrical  heater present, you need a pressure relieve valve for the pressure built up, on inlet water pressure, normally the  cold water from city, but in this case your pump from cold water tank?

Which is also with general electrical heaters, they have a pressure relieve valve  in the inlet.

Ok was reading again, but it doesnt say where the water, inlet solar heater is coming from.

 

 

I dont know now where you get the water from to feed the solar panel. You want to drain the water tank on the solar system by a pump and then mix it with cold water for 50 degree water instantly? 

You say pumps are 750 W, though that doesnt say capacity, how much flow, m3/h or ltr/h. Though i already think they are big.

How much is the flow? You only have a tank of 150 liters or 300 depending on which you buy.

When you are draining warm water, cold water will come in at the inlet and mix some with the warm water as wel.

If you have a pump doing  60 l/m, it is gone in minutes, of course restricted by piping.

Which again can cause oscillating of the pumps if they have pressure switches on them?

Be aware, what you take out , you must put in. Otherwise you can have vacuum in system and all implode.

System is not built for vacuum

  

 

You have hailstorms, well ask seller if it can take it. About thermal shocks, you can have hot day and then it starts to rain hard, then you have thermal shock as wel. The "glastubes" are not in contact with the water to heat, but  around the pipes to heat. 

Another thing is Ph of the water. In Thailand Ph can be low, acid. The plastic pipes can stand it, but metal cant in longer or shorter time, especially with higher temperatures. It gets more aggressive. Your pipes will solve and finally leaks by holes made by the acid substances in the water. Good to know if heater can stand the Ph.

7 is neutral, no problem, some higher no problem then it is base, but lower then acid which can corrode your metal pipes. Also your pumps.

Also important how much calcium is there in the water? If the water is hard, you can have scaling in your pipes, which will effect efficiency. Also other, solid, particles can cause scaling. Maybe a filter in inlet water?   

[KhaoYai]

A little different to what the OP is asking but I am more than happy with my airsource heat pump. At 50K baht it was far from cheap and I don't have solar. The hardest job I encountered was installing the pipework in an existing property (none showing anywhere) but even that wasn't too bad as I was doing a full refurb - except for in the suspended ceiling, that was a pain. No extra pump required (as long as you have a decent one already) and the unit incorporates its own pressure vessel. Simply provide a water supply and a normal electric socket.

 

I love these units - 1.3kw in, 4kw out, magic!

 

New house being built before too long will definitely use one of these units but the house will also be solar powered.  Quite where I'll buy another airsource heatpump from, I know not at the moment as the supplier of the one I have has retired and closed the factory. They are available in Europe but at 3 -4 times the price. I'll find one when I'm ready.

[KhaoYai]

7 hours ago, xtrnuno41 said:

The plastic pipes can stand it, but metal cant in longer or shorter time, especially with higher temperatures.

Use PPR - the green stuff available at many DIY outlets. The 'welder' is bit of a pain in tight spaces and you need 3 hands - I burned my arms to hell in the suspended ceilings ????.  I think using PPR on a new build would be much easier but if I was doing the job again, I'd probably import a quality pushfit system and a few spare joints.

[thaisail]

7 hours ago, xtrnuno41 said:

The system is used to heat with solar heat by natural circulation. Cold water leaves to the pipes and warm water goes up again, all in same tank. On top of the tank you have the outlet for hot water and on bottom cold in.

You need solar time for heating, you cant go too fast by pumps and force a bigger flow.

As there is also an electrical  heater present, you need a pressure relieve valve for the pressure built up, on inlet water pressure, normally the  cold water from city, but in this case your pump from cold water tank?

Which is also with general electrical heaters, they have a pressure relieve valve  in the inlet.

Ok was reading again, but it doesnt say where the water, inlet solar heater is coming from.

 

 

I dont know now where you get the water from to feed the solar panel. You want to drain the water tank on the solar system by a pump and then mix it with cold water for 50 degree water instantly? 

You say pumps are 750 W, though that doesnt say capacity, how much flow, m3/h or ltr/h. Though i already think they are big.

How much is the flow? You only have a tank of 150 liters or 300 depending on which you buy.

When you are draining warm water, cold water will come in at the inlet and mix some with the warm water as wel.

If you have a pump doing  60 l/m, it is gone in minutes, of course restricted by piping.

Which again can cause oscillating of the pumps if they have pressure switches on them?

Be aware, what you take out , you must put in. Otherwise you can have vacuum in system and all implode.

System is not built for vacuum

  

 

You have hailstorms, well ask seller if it can take it. About thermal shocks, you can have hot day and then it starts to rain hard, then you have thermal shock as wel. The "glastubes" are not in contact with the water to heat, but  around the pipes to heat. 

Another thing is Ph of the water. In Thailand Ph can be low, acid. The plastic pipes can stand it, but metal cant in longer or shorter time, especially with higher temperatures. It gets more aggressive. Your pipes will solve and finally leaks by holes made by the acid substances in the water. Good to know if heater can stand the Ph.

7 is neutral, no problem, some higher no problem then it is base, but lower then acid which can corrode your metal pipes. Also your pumps.

Also important how much calcium is there in the water? If the water is hard, you can have scaling in your pipes, which will effect efficiency. Also other, solid, particles can cause scaling. Maybe a filter in inlet water?   

The tank is vented so it is impossible to build up pressure. The pumps are automatic pumps that cut in at 1.3 bar and cut out at 2 bar. They will only run when you open a faucet. The newer design tank is full of copper coils and the same water that feeds the tank to fill it through an automatic filling system will also run water into the copper coil inside the tank. It will enter the coil cold and pick up heat from the tank water and come out of the coil with a temperature about 2° colder than the hot water in the tank. This water will be at the same pressure as the cold water system. The second pump shown in the photo will not be used in this case but can be kept as a spare. 

 

My cold water is first supplied by a submersible well pump that is inside a 40 meter deep well. That water is pumped into a 1000 liter tank using a mechanical float switch that will stop the pump when the tank is full and when the tank level drops to 200 liters, the submersible pump will turn on again and fill the tank. I imagine that pump will only run once or twice a day for about 5-10 minutes each time.

 

Cold water will feed into the copper coil in the solar tank only when you open a hot water tap in the house. As the cold water passes through the copper coil surrounded by water heated by the sun, it will absorb the heat from the 150 liter tank and the water will cool down a bit. But remember that there is a thermostatic controlled mixing valve that will add cold water after the water leaves the solar heater and should cool the water that could be as hot as 90° down to 50°. So on a hot sunny day I should be able to get more than 200 liters of 50° water which will be enough to fill my bathtub in the evening. I don't plan to buy the electrical immersion heater as I don't think I will need it but if I do buy from this Chinese solar factory the cost is only $12 US for 1500 watt with built in thermostat. At the latitude of Chiang Khan this heater may not be needed except for about 10 days out of the year and in this case I have one bathroom fitted with a 3.5 Kw single use water heater for those days without sunshine or during maintenance of the solar water heater.

 

The vacuum tubes are strong enough to handle hail up to a certain diameter. In the event of hail storms, I will try to cover the tubes with a sheet of hard plastic or ply wood to protect the glass. This 15 tube unit comes with 5 spare tubes as a precaution. As for heat transfer, since these double wall glass tubes are in a vacuum, there is almost no heat transfer when there is no sun, rain or at night. The water is heated in a way that allows heat to be absorbed but cannot pass through outward through the vacuum to escape the heater through the glass.

 

As for the water quality, since the water in the well can be either acid or basic, I can treat the portion of water that surrounds the copper coil with chemicals as needed. The water under pressure through the copper pipe will not be treated but if scaling occurs, I can take the heating coils out of sevice and circulate de-scaler through the copper pipe as needed. That water circulating through the glass vacuum tubes will be stagnant water and will only need to be replaced in the event of steam when it will boil in the 45° summer in March and April. Since my heater will be mounted only 2 meters above the ground, all of the service and maintenance will be easy to perform.

 

As for metal pipes getting corroded, the system I put in has only copper pipe and stainless steel tank. There will be a maganisium anode to protect the tank against electrolysis from dissimilar metals. There is normally a 15-20 year service life if the anodes are maintained. The only thing fragile on this system are the glass tubes and they are not expensive and normally last for 15 years minimum unless there is a horrific hail storm.

 

I have already bought a 30 micron water filter to clean the well water as it fills the 1000 liter water storage tank and the solar heater comes with a small secondary filter at the water inlet. If the water turns out to be too hard, I will have to fit an ion exchange water softener but I am told that the water in my area is good quality and my wife is happy with the laundry!

 

[thaisail]

1 hour ago, KhaoYai said:

Use PPR - the green stuff available at many DIY outlets. The 'welder' is bit of a pain in tight spaces and you need 3 hands - I burned my arms to hell in the suspended ceilings ????.  I think using PPR on a new build would be much easier but if I was doing the job again, I'd probably import a quality pushfit system and a few spare joints.

I know what you mean about 3 hands to operate the welding machine. My 600 baht Chinese heater from Lazada had an explosion in the wire going to the plug and the cable caught fire. The liquid burning metal from the burning wire burned a hole on my shorts and left we with a tiny burn scar on my leg! I recommend everyone to spend a bit more money on the heater and the PP-R pipe cutting tool. I agree with you about PP-R being the best option for constructing a new house but the Thai workers here in Chiang Khan don't want to work with the welding and I had to make all the welds.

[KhaoYai]

19 minutes ago, thaisail said:

My 600 baht Chinese heater from Lazada had an explosion in the wire going to the plug and the cable caught fire.

I believe mine cost 3000 baht - bought from the same place I bought the pipe from. But yes, I bought a Chinese soldering iron (150 baht - thought it was too good to be true), the gun shaped type - metal electrical parts, encased in plastic.  The first time I used it and applied a tiny amount of pressure to the item I was soldering via the tip - the tip slowly disappeared into the plastic casing - really good idea that ????.

 

On the serious side, these bloody things are dangerous, there's no way they'd get away with selling such rubbish in the UK

[brianthainess]

A 100 mtr coiled length of 32mm black poly water pipe would be the way to go for me 1,200 baht. and obviously  mixer taps. lived on a farm in OZ once they just ran the pipe around inside the gutter, ''she'll be right mate'' and it was.

[thaisail]

5 hours ago, brianthainess said:

A 100 mtr coiled length of 32mm black poly water pipe would be the way to go for me 1,200 baht. and obviously  mixer taps. lived on a farm in OZ once they just ran the pipe around inside the gutter, ''she'll be right mate'' and it was.

The average shower uses 60 liters of water. By my calculations our black hose will contain 80 liters of water. If this water reaches 80° C, you will have mix about another 80 liters of cold 20° water to get the temperature down to around 50°C. That will give you roughly 160 liters of hot water. Not bad if you take your showers at 3 PM. But by 5 PM, the water in your black hose will start cooling down and one hour after sunset the water will be almost at ambient temperature. This means no hot water for showers from 8 PM until around 10 AM the following day. Of course if the afternoon is cloudy or rainy, there will be very little hot water for use after dark. 

 

The system I propose will drop less than 5° C during the night if no water is used. But remember the solar tank has a threaded hole that can fit a 1500 watt immersion heater. This may not be needed depending on how much hot water is consumed at night. 

[brianthainess]

18 hours ago, thaisail said:

The average shower uses 60 liters of water. By my calculations our black hose will contain 80 liters of water. If this water reaches 80° C, you will have mix about another 80 liters of cold 20° water to get the temperature down to around 50°C. That will give you roughly 160 liters of hot water. Not bad if you take your showers at 3 PM. But by 5 PM, the water in your black hose will start cooling down and one hour after sunset the water will be almost at ambient temperature. This means no hot water for showers from 8 PM until around 10 AM the following day. Of course if the afternoon is cloudy or rainy, there will be very little hot water for use after dark. 

 

The system I propose will drop less than 5° C during the night if no water is used. But remember the solar tank has a threaded hole that can fit a 1500 watt immersion heater. This may not be needed depending on how much hot water is consumed at night. 

In that case you may as well have an electric shower.

[Yellowtail]

2 hours ago, brianthainess said:

In that case you may as well have an electric shower.

 

Having a heating element that kicks in at night or on cloudy days is not the same as having an electric shower. That is like saying tying your solar powered home to the grid in the event your panels do not generate enough electricity is the same as a home that gets all of it's electricity from the grid. 

[thaisail]

7 hours ago, Yellowtail said:

 

Having a heating element that kicks in at night or on cloudy days is not the same as having an electric shower. That is like saying tying your solar powered home to the grid in the event your panels do not generate enough electricity is the same as a home that gets all of it's electricity from the grid. 

I agree! I do not think I will need the electric heating element but it is a nice option and only 1500 watt instead of 3500 watt. But my garage bathroom has one 3500 watt shower already. We are all showering in the garage for the moment!

 

But we have the main bathroom with a bathtub and a shower and no hot water yet. We also have the bungalow by the pond with no hot water yet. We did put a hot water PP-R pipe under the concrete driveway so when we get our solar water heater, we will be able to connect hot water to the bungalow also.