House near Rattanaburi, surin

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Re: House near Rattanaburi, surin

Postby tertim » Mon Aug 21, 2017 10:12 pm

qwerty wrote:Tertim, could I possibly ask some questions and advice based on your solar water heater experience?

1. What is the diameter of your collector pipework? I have seen some different diameter & size coils of black LDPE in Global House: 2”x50m, 1½”x100m, 1”x200m.
Is there a size you might suggest using, based on your experience?

2. From your photos, your collector looks perhaps two metres high? I initially envisaged putting the collector plate on the roof, three metres high.

3. You used a 200 litre water tank, is it an easily available type, did you buy it from a national DIY outlet for example?
There was some correspondence about the height of the return connection on the tank. I’m under the impression the tank has the same water in that’s circulated from the collector, and they aren’t two separate systems (i.e. a coil inside the water tank to the collector, separate from the domestic hot water)?

4. I assume you didn’t alter the height of the return, as you added a solar powered pump instead?
I saw recently Tool Pro had solar cell array on wheels, with water pump (but no batteries) for 16,000B. That seemed expensive to me, but perhaps it’s the going rate?
It looked like you had a battery and controller for yours. Is that necessary, as the pump only needs to run during daylight hours?

5. You fitted a differential thermometer to control the pump. Any details of the spec of that one, and the price and availability?



Hi qwerty
Thank you for your interest I will try and answer your queries as fully as possible but first of all some background info on my design and an update on the past 7 months of running my solar water heater.

As you are probably aware from my previous post I started off with a system some guys in Nepal were using but i failed to get it working(I will come back to this later) so then I went with a pumped system which after 7 months of operation has been an unqualified success producing an abundance of hot water (60c) with no breakdowns or any issues whatsoever.
In these 7 months we had a 4 day period of continuous rain and overcast conditions and on the 4th night we used our back up electric water heater for one night only, it's only 3KW and is plumbed into the hot water circuit to supply the 2 bathrooms and kitchen it plugs into a standard power socket.


OK your queries:-
1 I used 20mm LDPE x 100M there are two thicknesses available I used the thinner one but would have preferred the thicker wall one but it was out of stock at the time

2 My collector is mounted on an adjustable swivel so it can be adjusted to give the optimum angle to the sun, in retrospect I don't think this is necessary as we have more than enough hot water, for the future I would just site the collector to decline 15deg south(for my location)

3 The tank I used is standard 200L plastic barrel used in the transportation of various liquids around the world, its immensely strong and is made of two types of plastic bonded together, I bought it second hand from a car wash place(B600) you would need to make sure it didn't harbour any nasty chemicals, mine was used for detergent so after a thorough wash it was OK. You are correct the water in the hot water storage tank(200L barrel) is pumped through the solar collector and returned to the barrel, both of these pipes enter the barrel at the top the pumped one going to the bottom and the return about 20cm below the water level(this important as the pump only has to provide a flow as against having to produce a head)
In the hot water storage tank the flow pipe(cold) to the collector needs to be at the bottom of the tank and the return pipe(hot) from the collector needs to be at the top of tank, this applies to a pumped or syphonic system, I think the guy who raised this omitted to do his research and seemed a little confused about it.

5 The differential thermostat I bought on ebay for about $30 including postage I will try and find a link for you. I decided to fit a battery and controller to even out the voltage supply to the pump, you could just wire up the pump directly to the solar panel but I was concerned that the pump motor would burn out prematurely when the solar panel was not supplying enough charge.

https://www.ebay.co.uk/sch/i.html?_from ... r&_sacat=0

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Re: House near Rattanaburi, surin

Postby unclezillion » Tue Aug 22, 2017 10:53 am

I skimmed through the last few pages, however, my post is concerning soil erosion around your pond.
i built a 10 rai lake in Rayong. at one end we had a 5M mound of sandy soil about 100M x 50 M. to stop it eroding we used what was called called Brazillian grass
down there. another of the late King's ideas! it is in fact Vetivert and is renowned for its extensive root system.
The long and short of it was we planted in the dry season and watered weekly. we hardly lost any soil to erosion during the wet season but did a little.
all erosion was arrested after 2 years.
May be worth a look :) Image
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Re: House near Rattanaburi, surin

Postby qwerty » Tue Aug 22, 2017 10:59 am

Thanks to everyone who took the time to reply, putting me right on the most aspects of the solar pump and controller, having absolutely no experience of solar cells.
Schulmmpge, you offered a lot of detail for a solar pump installation and what to look for. Thanks.

Tertim, Thanks for answering my points, and the details of the tank and the differential thermostat. It seems you used the 1” pipe (from my list).
Why would you have preferred the thick wall version? I would have thought the thinner one would absorb the heat into the pipe water faster?
You said you used 100m. Does that refer to the length of pipe you bought, or the actual length in the collector?

Looking at the blue plastic tank, it seems to have a lid fitted on the top. Did you have seal this somehow, to prevent water leaking out?

My domestic cold water installation consists of two 800 litre storage tanks, fed via a float valve from city water, filled using just the city water pressure.
The feed out from the two tanks goes to a pump, which supplies everything around the house. So my domestic water is pressurised, which would feed into any hot water storage tank I fitted. Hence my question about sealing the lid of your tank.

Initially I’m just going to feed a collector to one tap and do some testing that way first. Therefore the volume of hot water can only be the volume of the collector pipework. If for example I had a collector with 1” pipework of 100m, that would give me about 50 litres of water in the collector.
I want to take it steady to see how it pans out.
Assuming I get positive results, I would progress to a hot water storage tank.
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Re: House near Rattanaburi, surin

Postby tertim » Tue Aug 22, 2017 4:28 pm

unclezillion wrote:I skimmed through the last few pages, however, my post is concerning soil erosion around your pond.
i built a 10 rai lake in Rayong. at one end we had a 5M mound of sandy soil about 100M x 50 M. to stop it eroding we used what was called called Brazillian grass
down there. another of the late King's ideas! it is in fact Vetivert and is renowned for its extensive root system.
The long and short of it was we planted in the dry season and watered weekly. we hardly lost any soil to erosion during the wet season but did a little.
all erosion was arrested after 2 years.


Hi unclezillion
I ended up building a wall of sandbags almost 3 Metres high and 2M wide and backfilling everything covering over the sandbags, we then planted loads of vetiver grass which has now taken hold also I managed to divert 95% of the water that was causing the problem. So all looks good now but shall be keeping an eye on it for the next few seasons.

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Re: House near Rattanaburi, surin

Postby tertim » Tue Aug 22, 2017 5:09 pm

qwerty wrote:Thanks to everyone who took the time to reply, putting me right on the most aspects of the solar pump and controller, having absolutely no experience of solar cells.
Schulmmpge, you offered a lot of detail for a solar pump installation and what to look for. Thanks.

Tertim, Thanks for answering my points, and the details of the tank and the differential thermostat. It seems you used the 1” pipe (from my list).
Why would you have preferred the thick wall version? I would have thought the thinner one would absorb the heat into the pipe water faster?
You said you used 100m. Does that refer to the length of pipe you bought, or the actual length in the collector?

Looking at the blue plastic tank, it seems to have a lid fitted on the top. Did you have seal this somehow, to prevent water leaking out?

My domestic cold water installation consists of two 800 litre storage tanks, fed via a float valve from city water, filled using just the city water pressure.
The feed out from the two tanks goes to a pump, which supplies everything around the house. So my domestic water is pressurised, which would feed into any hot water storage tank I fitted. Hence my question about sealing the lid of your tank.

Initially I’m just going to feed a collector to one tap and do some testing that way first. Therefore the volume of hot water can only be the volume of the collector pipework. If for example I had a collector with 1” pipework of 100m, that would give me about 50 litres of water in the collector.
I want to take it steady to see how it pans out.
Assuming I get positive results, I would progress to a hot water storage tank.


hi qwerty

The pipe I used was definitely 20mm I wanted the thicker pipe for reasons of longevity hopefully the pipe will last a good few years before it needs replacing, I used 90M in the solar collector and about 10M to connect to the hot water tank.

The hot water tank is not pressurised it is open vented to the atmosphere it has a lid but it is certainly not watertight, cold water is fed in from the main water pipe and the level is controlled with a simple float valve this water is directed to the bottom of the tank so as not to cool the hot water at the top of the tank.
Hot water is pumped from the tank approximately 30cm below the water level( to make sure no air enters the pipe ) via a small pressure regulated pump into the domestic hot water plumbing.
It would seem that you are describing a pressurised hot water tank which would be a very good system albeit quite expensive.

When I set out to build my system cost was a consideration as I wasn't sure how it would perform also KISS, I've spent about B5000 on the materials but most of this went on the controls (Solar panel,controller, differential thermostat, battery and pump) so you can see if you build a thermosyphon system the cost is negligible and is very simple with zero maintenance costs.

Next year I want to build a thermosyphon system to try out. Here's a link to a good site for solar heaters http://www.builditsolar.com/

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Re: House near Rattanaburi, surin

Postby qwerty » Wed Aug 23, 2017 7:17 pm

Hi tertim,

It was a bit of a downer when I realised your tank was open-vented. It didn’t enter my mind to query it before.
I can see two ways forward for me to go ahead. Either add a new unpressurised system for hot water using a tank similar to what you have. Or, keep it all pressurised and pay for a sealed tank (I think it would be too difficult to try and seal a manually-adapted tank.)

I’ve been looking around for the past couple of days, and have seen a steel tank in DoHome. There’s a 200 litre size available and has four tapped connections to it.
At the side - top and bottom could be use for flow & return from the collector. On the domed top is a tapped connection which could be the domestic hot water out. On the underside of the tank, on the domed base is another connection which could be the cold water inlet.

The drawback is the price at 5,500 Baht. That will make the cost of the project around 10,000 Baht, more than I had hoped.
I don’t if anyone might have any comments on my idea of using this tank?
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Re: House near Rattanaburi, surin

Postby Sometimewoodworker » Wed Aug 23, 2017 8:13 pm

qwerty wrote:Hi tertim,

It was a bit of a downer when I realised your tank was open-vented. It didn’t enter my mind to query it before.
I can see two ways forward for me to go ahead. Either add a new unpressurised system for hot water using a tank similar to what you have. Or, keep it all pressurised and pay for a sealed tank (I think it would be too difficult to try and seal a manually-adapted tank.)

I’ve been looking around for the past couple of days, and have seen a steel tank in DoHome. There’s a 200 litre size available and has four tapped connections to it.
At the side - top and bottom could be use for flow & return from the collector. On the domed top is a tapped connection which could be the domestic hot water out. On the underside of the tank, on the domed base is another connection which could be the cold water inlet.

The drawback is the price at 5,500 Baht. That will make the cost of the project around 10,000 Baht, more than I had hoped.
I don’t if anyone might have any comments on my idea of using this tank?

Unless you are buying a commercial system then a pressurised one raise all sorts of problems, just one is that AFIK the LDPE pipe isn't pressure rated neither are the fittings and that's just one.

Your house water supply certainly isn't a pressured one.
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Re: House near Rattanaburi, surin

Postby qwerty » Wed Aug 23, 2017 8:22 pm

OK, wrong choice of words, I was following how tertim described it, I think we understood each other. How about a fully pumped system. Is that better?
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Re: House near Rattanaburi, surin

Postby Sometimewoodworker » Wed Aug 23, 2017 8:57 pm

qwerty wrote:OK, wrong choice of words, I was following how tertim described it, I think we understood each other. How about a fully pumped system. Is that better?

More accurate I would think. I would also think there would be no need for the kind of tank you show, a regular tank with a float valve would do. You might want to pump the hot water to the taps depending on its location and the kind of taps you use.
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Re: House near Rattanaburi, surin

Postby tertim » Thu Aug 24, 2017 9:52 am

qwerty wrote:Hi tertim,

It was a bit of a downer when I realised your tank was open-vented. It didn’t enter my mind to query it before.
I can see two ways forward for me to go ahead. Either add a new unpressurised system for hot water using a tank similar to what you have. Or, keep it all pressurised and pay for a sealed tank (I think it would be too difficult to try and seal a manually-adapted tank.)

I’ve been looking around for the past couple of days, and have seen a steel tank in DoHome. There’s a 200 litre size available and has four tapped connections to it.
At the side - top and bottom could be use for flow & return from the collector. On the domed top is a tapped connection which could be the domestic hot water out. On the underside of the tank, on the domed base is another connection which could be the cold water inlet.

The drawback is the price at 5,500 Baht. That will make the cost of the project around 10,000 Baht, more than I had hoped.
I don’t if anyone might have any comments on my idea of using this tank?



Hi qwerty
When I bought my LDPE pipe at TW they had a chart for the pressure rating of the various pipe sizes the larger sizes being up 10 Bar ( if I remember correctly ) the smaller sizes were considerably less, when you consider that your collector will be operating at temperatures in excess 70c the pressure rating would drop drastically so a pressurized system would be unsuitable using LDPE pipe, your best option would be an unpressurised system.

When choosing a tank to store the hot water you must make sure that it is rated to at least 70c or you may have problems with the tank melting!!!! the plastic tanks available in the stores are made from quite thin plastic that is why I chose my 2nd hand barrel which is very substantial and so far shows no sign of deterioration.

No sure why SW thinks you don't have a pressurised cold water system, if you have a pump from your water tanks to supply water to you faucets then that is a pressurized system!! You will of course need a pump to draw water from your hot water tank into your plumbing pipework, they are not too expensive B1300 at your local hardware shop.

IMG_20170824_085325.jpg
Pump on the left is for cold water and on the right hot water they are both set to kick in at 1.5 BAR and out at 2 BAR


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Re: House near Rattanaburi, surin

Postby qwerty » Thu Aug 24, 2017 11:28 am

Thanks again for all the responses to my questions/comments.

“Pressurised” vs “pumped” I’m sure we could argue about this until the cows come home.
Yes, I suppose anything that is pumped is under pressure. In the UK we tend to refer to a pressurised central heating system as one which is completely sealed. IIRC they tend to run at anything from 0.5–2 bar depending on the installation. To top up the pressure (one the ones I saw) you had to add a mains water link pipe via a valve, to increase it the required level.

Tertim, although your system and mine is pumped and therefore under some pressure, it’s not sealed. I’m guessing now, that’s what SW is referring to?

When I looked at that stainless steel tank, the spec said it was resistant to a maximum of 90 degrees C. It had occurred to me your plastic tank may become soft under excessive heat?
I don’t know if a steel tank might not be as effective regarding keeping the water hot, any more than a plastic tank might, as long as they’re both lagged. However, I’m willing to be corrected on that one.

I’m still thinking of using the one cold water pump to feed the hot water around the system. So it will be pushing the hot water around, rather than pulling it with a hot water pump. I don’t imagine it would affect the solar powered pump circulating the collector water, any more than your system does with a vented tank and a separate hot water pump? It will all be interesting.

As I said before, I want to try and plan the complete system first. Then I’ll start by testing one tap directly from the collector coil, to see how that pans out, before buying a water tank.

I don’t know if a ‘clip on’ or ‘stick on’ thermometer is easily available, to measure the water temperature (before I buy a differential thermostat)? I saw some images of digital thermometers for fish tanks, so perhaps I should try an aquatic shop.
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Re: House near Rattanaburi, surin

Postby tertim » Thu Aug 24, 2017 1:13 pm

Hi qwerty
From your reply it seems that you have experience of plumbing and CH systems in the UK so you will be aware that the steel tank would need to be indirect (heat exchanger coil inside tank) this would then allow you to connect to your solar collector open vented, you would of course need a small tank to keep this circuit topped up.
Also don't forget to install an expansion vessel along with a blow off valve.

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Re: House near Rattanaburi, surin

Postby qwerty » Thu Aug 24, 2017 4:37 pm

Hi tertim,

Yes, I did do heating repairs for five years. The only thing is that was thirty years ago!

When you say I would need to make the tank indirect, with a coil inside, that is not really going to be an option in the stainless steel tank I looked at, as the only access is via the four tapped holes.
I was envisaging it as a direct cylinder, where the collector coils would feed in and out of the two tapped holes on the side of the tank, circulating with the domestic hot water.

Going back fifty plus years, that was a common setup in the UK, where coal-fired back boilers were popular. It meant the water in the heat exchanger used gravity to circulate upstairs to the hot water cylinder. (we hadn’t heard of the word thermosyphon then). The water that was in the back boiler would be the same water coming out of the hot tap, it wasn’t separated.
The copper hot water cylinder was called a direct cylinder, (as opposed to indirect with a coil). I see the phrase 'direct cylinder' now seems to refer to one with only an immersion heater element in it.

But I digress. As I have no experience of solar heating, do you have any opinion if it would be practical to have the collector coil being pumped around a ‘direct cylinder’ installation?
I take your point about a pressure relief valve and an expansion vessel, as it would be an unvented system. Thanks for mentioning it.
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Re: House near Rattanaburi, surin

Postby Sometimewoodworker » Thu Aug 24, 2017 4:44 pm

tertim wrote:Hi qwerty
From your reply it seems that you have experience of plumbing and CH systems in the UK so you will be aware that the steel tank would need to be indirect (heat exchanger coil inside tank) this would then allow you to connect to your solar collector open vented, you would of course need a small tank to keep this circuit topped up.
Also don't forget to install an expansion vessel along with a blow off valve.

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Assuming that you are just using the house pump, why would you need to use heat exchanger coils? I'm guessing that your system doesn't use them.
I'd be interested to understand the system you envision using the coils

I'm guessing that the system envisioned is

Cold water side; direct from house pump to the outlet.
Hot water side; basically a very long route from the house pump through the LDPE pipes to the outlets.

This would probably work OK.

If you are going to add in a storage tank then you would almost certainly need a second house pump, to pump the hot water.

The commercial systems available costing many thousands of baht (40,000~80,000) use indirect, heat exchanger coils, heating, vacuum sealed glass collection units, built in pumping of the glycol mix exchang medium etc. These are designed for cold weather conditions and while they certainty work and probably get high temperature water I think they are overkill for Thailand
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Re: House near Rattanaburi, surin

Postby tertim » Thu Aug 24, 2017 6:16 pm

qwerty wrote:Hi tertim,


But I digress. As I have no experience of solar heating, do you have any opinion if it would be practical to have the collector coil being pumped around a ‘direct cylinder’ installation?
I take your point about a pressure relief valve and an expansion vessel, as it would be an unvented system. Thanks for mentioning it.


Hi qwerty
The problem will be the LDPE pipe in the solar collector, I just don't think it will be able to withstand the 70c plus temperatures and a water pressure of say 2 BAR, this is only my opinion and is not based on any experience using LDPE under pressure and higher temperatures.
In your original posts you said you wanted to build a system for a reasonable budget and if this is still the case then I would go with something the same as I built, at least you know it works and performs well.

Pop kan mai

PS I can still remember our bath nights on a saturday in the early 50s, yes a bath once a week whether we needed it or not!! being the youngest of the brood I was last in line. Throw an extra bucket of coal on the fire and pull out the damper, my sons still can't believe I led such a primitive live and think i'm joking!!!!!
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