[black12rr]

The Diagram needs to be corrected i think . Hot water is tapped at the top the collector tank and clod water enters the tank from the bottom .

[sudev]

The diam gram was purely for the purpose of expansion chamber placement discussion. The tap for hot water is at bottom only as the heat exchanger-cum tank drains by gravity only. If it was forced circulation system then may be .....

And need to add that the maint. cost was NIL.

[deky]

I have gone thru the complete thread and have tried to understand the pros & cons of the solar heater. There seems to be more pros than cons for this system.

But since this thread has not been updated for about a year and I am sure since May'09 more members must have added solar geysers to their homes also new technology must have come in, so I would like to know any updates on the topic.

Also The Rajasthan Govt has come out with a notification that all industrial units, hospitals, hotels should have solar heating by March'10, which I think is a good move. To meet the requirements I also need to change from existing individual geysers to Solar geysers in the guest toilets. But I need people who have used it to answer me some of my querries.

1. Which type is better, the flat panel type or the vaccum tube type?
2. How much water should we take that every person consumes per shower to calculate the right size of the storage tank?
3. is scaling and deposits a problem where the water is hard?
4. Is pressurized pump a good idea or gravity is sufficient for water to circulate from over head storage tank to solar geyser and then to taps.
5. how much is the heat loss over night if the hot water is not drawn from the collector? I mean if at 1900 hrs the water temperature is 65 degress and no water is drawn (means no cold water will be added to the collector tank) what will be the water temp at 0900hrs next morning?
6. This is important. For a guest house like mine, where guests prefer having a bath at night, where do i get the hot water required for them for next day at 0700 hrs next morning. Do I use electricity back up? If I do that on a daily basis, how do I save on electricity?
7. for cold foggy winter mornings when the sun comes out at 1100hrs, how do I heat water when I require it for guests??

For a place like jaipur, 6 summer months out of 12 months, we do not require hot water, and also for the remaining 6 months if we using electric back up for the 3 months, do you guys think its practical and feasible to invest in solar geyser for 3 months.

Kindly let me know your inputs on these

Thanks and regards

[aaggoswami]

Originally Posted by deky

1. Which type is better, the flat panel type or the vaccum tube type?

2. How much water should we take that every person consumes per shower to calculate the right size of the storage tank?

3. is scaling and deposits a problem where the water is hard?

4. Is pressurized pump a good idea or gravity is sufficient for water to circulate from over head storage tank to solar geyser and then to taps.

5. how much is the heat loss over night if the hot water is not drawn from the collector? I mean if at 1900 hrs the water temperature is 65 degress and no water is drawn (means no cold water will be added to the collector tank) what will be the water temp at 0900hrs next morning?

6. This is important. For a guest house like mine, where guests prefer having a bath at night, where do i get the hot water required for them for next day at 0700 hrs next morning. Do I use electricity back up? If I do that on a daily basis, how do I save on electricity?

7. for cold foggy winter mornings when the sun comes out at 1100hrs, how do I heat water when I require it for guests??

For a place like jaipur, 6 summer months out of 12 months, we do not require hot water, and also for the remaining 6 months if we using electric back up for the 3 months, do you guys think its practical and feasible to invest in solar geyser for 3 months.

Kindly let me know your inputs on these

1) Earlier we had Flat panel type, now we have Vaccum tube. We realized that Flat panel had better performance. In flat panel, if one wants hot water at 2:00 am, its possible in winter also. If 4:00 am, still no problem.

We are a family of four. All have habit of taking bath twice. I take bath late at around 12:00 in night, and at 6:00 am next morning, still hot water was available.

Its that good. Second thing is that washing the panels is better and easier in case of flat panel. Cleaning the vaccum tubes is not an easy job, its more cumbersome.

Also watch out for any open pipes or central members from where the water enters those tubes. Here maximum heat loss from water will be there. If not insulated properly, you will not get hot water. If a person takes bath at 11:00 pm, then next morning 6:00 am, its cold water.

However, this can vary from design to design. Have a look at how water flows and all the pipes must be well insulated. This is critical.

2) Calculate 50 ltrs. per person. That is bare minimum. Also depends upon how the water will be used.

EG : Using water for washing clothes. Next varied timing of taking bath for different family members.

3) That wont hit very hard, but the various seals will need replacement.

4) Avoid pressurized pump. Install that pressurized pump only if you are not able to arrange for overhead tank. Less complications, the better.

5) Heat loss is less in case of Flat panel. But Vaccum type can also be efficient. Depends on how water flows and how much insulation is there.

6) Well, if you make electricity back up, you will end up losing more money. Its only for emergencies. Keep it only for backup. Flat panel is a good option IMO. Note that earlier we had that system and right now we have vaccum type which is almost meaning less except one bath.

7) In worst case, use electric back up. Otherwise, there will be sufficient storage in solar geyser tank.

Right now, I am really not in good health ( its like this for over 10 days now ). As soon as I find time, I will upload the images of our current system and will also show the place where we lose on maximum heat from water.

[deky]

Thanks for the prompt response, my questions are in bold!!

Originally Posted by aaggoswami

1) Earlier we had Flat panel type, now we have Vaccum tube. We realized that Flat panel had better performance. In flat panel, if one wants hot water at 2:00 am, its possible in winter also. If 4:00 am, still no problem.

I did some home work and called a few dealers. Vaccum type comes out to be 20% cheaper (initial cost) than the flat panel. And also since the flat panel uses copper tubes the scaling problem is much more. But as you say the efficiency is less in flat panel then I would really have to weigh the pros and cons of both and then take a decision.

We are a family of four. All have habit of taking bath twice. I take bath late at around 12:00 in night, and at 6:00 am next morning, still hot water was available.

Whats the size of your vaccum geyeser for the 4 of you?

Also its good to know that hot water is available even at 6:00 am after using it for a bath at midnight. But do you think, it will be different here as its much cooler in jaipur?

Second thing is that washing the panels is better and easier in case of flat panel. Cleaning the vaccum tubes is not an easy job, its more cumbersome.

By cleaning do you mean dusting the dust off the panels or opening or cleaning the tubes?

2) Calculate 50 ltrs. per person. That is bare minimum. Also depends upon how the water will be used.
EG : Using water for washing clothes. Next varied timing of taking bath for different family members.

I know, this will be even more erratic in a guest house type of a situation. Also I guess at home most of us would use half of the water what we might use for having a bath in a hotel. So I guess the calculations should be about 100ltrs per person??

4) Avoid pressurized pump. Install that pressurized pump only if you are not able to arrange for overhead tank. Less complications, the better.

I have an overhead tank 12 feet above the terrace, so I think pump wont be needed then.

6) Well, if you make electricity back up, you will end up losing more money. Its only for emergencies. Keep it only for backup. Flat panel is a good option IMO. Note that earlier we had that system and right now we have vaccum type which is almost meaning less except one bath.

7) In worst case, use electric back up. Otherwise, there will be sufficient storage in solar geyser tank.

Point noted!! Thanks

Right now, I am really not in good health ( its like this for over 10 days now ). As soon as I find time, I will upload the images of our current system and will also show the place where we lose on maximum heat from water.

Oh Please take care of yourself, the pics can come later. Thanks for the quick response and do get well soon.

[sudev]

@deky: Cleaning of solar heating elements due to scaling is the biggest worry. If the water in your area is hard water then it is better to check with other local users (ask the company who is selling to give references) as water varies from area to area. I used vaccum tube type heater as this has two circuits - one for heating fluid and one for water (heating fluid is also water but just for clarity i used this word). The heating fluid scaling can be reduced by using DM water for first time filling and regular top up (or soft water like the 20 ltr water bottle).

You can add units of panels and increase capacity.

Cool climate at Jaipur s not relevant - more relevant is intensity of sunlight when available. In summers you can reduce the heating by covering the panels partially.

[aaggoswami]

Originally Posted by deky

Thanks for the prompt response, my questions are in bold!!

1) I did some home work and called a few dealers. Vaccum type comes out to be 20% cheaper (initial cost) than the flat panel. And also since the flat panel uses copper tubes the scaling problem is much more. But as you say the efficiency is less in flat panel then I would really have to weigh the pros and cons of both and then take a decision.

2) Whats the size of your vaccum geyeser for the 4 of you?

Also its good to know that hot water is available even at 6:00 am after using it for a bath at midnight. But do you think, it will be different here as its much cooler in jaipur?

3) By cleaning do you mean dusting the dust off the panels or opening or cleaning the tubes?

4) I know, this will be even more erratic in a guest house type of a situation. Also I guess at home most of us would use half of the water what we might use for having a bath in a hotel. So I guess the calculations should be about 100ltrs per person??

5) I have an overhead tank 12 feet above the terrace, so I think pump wont be needed then.

6) Oh Please take care of yourself, the pics can come later. Thanks for the quick response and do get well soon.

1) Yes, scaling is an issue and later on there is chance of internal leak also. But its not at the cost of efficiency. Vaccum tubes will give less hot water than flat panel. And its possible to use mineral water also for the liquid that heats up the water.

2) 200 ltrs. It was 200 ltrs. for flat panel also and its 200 ltrs. for vaccum type geyser.
Its how much the water has heated and this is decided about intensity of sunlight. If sunlight is good for the whole afternoon, its not much of an issue. Lets say that the sun comes out properly by 11:00 am and stays till 5, then this is good enough.

3) In vaccum type, cleaning the tubes, which is not easy. And for flat panel, its just washing off the panel. This is relatively easy and can be done by most of the people. For vaccum tubes one has to be a little bit more careful.

Make sure that cleaning is done either in early morning or by night. Dont do it in sunlight. This can crack the glass panel in case of flat panel as the glass would be hot and cold water will suddenly fall on it.

4) Correct. Its good to have a higher capacity.

5) Then no issue. Make sure that the ventilator pipe for solar geyser is above the water tank.

6) Thanks. Will update with pics as soon as possible.

[aaggoswami]

@deky : Here are images that I have taken. The best camera I have is my mobile phone's.

1) There are many other designs available that can be more efficient. We bought the what we felt was the best VFM.

2) Installing Union and valve at every inlet and outlet to the geyser is good. Fact is, when you have to shift geyser or diconnect geyser, then union becomes useful. Valve for obvious reasons when we want to supply.

I know all this because the earlier valve and union was useful when we had to remove flat panel geyser. And all the installation and piping was done under my supervision including fitting of vacuum tubes.

I have tried my best to show everything, if you have any further doubt, then post here. I will later on PM you my contact number.

[deky]

Thank You Sudev & Aaggoswami for the inputs and the photographs.

I have been checking out a few systems installed around my house lately and the efficiency the provide. Mostly are installed in houses so I do not know if I can compare them with hotels. Anyways here are a few more points.

1. why is a ventilator pipe important? I havnt seen it anywhere here except in your kind of set up.
2. what happens if the over head tank drains out, is there a vacuum created in the solar heater, will it create any problems?
3. that unions and valve is a good point, will definately keep that in mind.
4. I see that the insulation you have used on the open pipes is rope, is that right. What in your opinion will be the best insulation? Rubber on the pipes?
5. SUDEV :what exactly is heating fluid, and where is it put?? I thought the only fluid that is used is the water from over head tank, that is heated via convection?
6. AGGOSWAMI:The evacuated tubes or the vaccum tubes in your system are horizontal where as I have only seen them vertical. The principal behind solar heating is hot water rising and cold water settling down. Could that be one of the reasons for less efficiency?
7. Here is a web site that states why evacuated types are better than flat panel type. Would you like to read here and let me know your comments.

Thanks, I am not doubting when you say that you were happier with flat panel type but just trying to understand.

Thanks again and regards

[aaggoswami]

Originally Posted by deky

1. why is a ventilator pipe important? I havnt seen it anywhere here except in your kind of set up.

2. what happens if the over head tank drains out, is there a vacuum created in the solar heater, will it create any problems?

4. I see that the insulation you have used on the open pipes is rope, is that right. What in your opinion will be the best insulation? Rubber on the pipes?

5. SUDEV :what exactly is heating fluid, and where is it put?? I thought the only fluid that is used is the water from over head tank, that is heated via convection?

6. AGGOSWAMI:The evacuated tubes or the vaccum tubes in your system are horizontal where as I have only seen them vertical. The principal behind solar heating is hot water rising and cold water settling down. Could that be one of the reasons for less efficiency?

7. Here is a web site that states why evacuated types are better than flat panel type. Would you like to read here and let me know your comments.

Thanks, I am not doubting when you say that you were happier with flat panel type but just trying to understand.

1) Not to take risks. You would have noticed that our tank ventilator ( earlier this was the only ventilator for both, normal cold water coming down into house and for cold water going in solar geyser ) was sufficient as the earlier flat panel system was just below the water tank. Currently, the solar geyser is quite far, so we never wanted to take any chance. And this was also recommended.

2) One of the reasons for the ventilator. If there is no water in overhead tank and if the ventilator pipe is far away, there are chances of crack. Normally, if the ventilator pipe is installed, then even if overhead tank does not have water, things wont go bad.

Note that the ventilator pipe in our vaccum geyser is present only because the water tank is far. Earlier in flat panel system just below water tank, it was not required ( I have indicated in one of the diagrams where the earlier flat panel system was there ).

4) No, ropes is not right. It actually wont help. I have seen rubber at one place and it was good enough. But not sure what would the best. The best insulation I have seen so far is rubber on hot water pipe and that whole pipe was kept inside a plastic pipe of bigger diameter. Over the time, rubber melt is an issue.

Foam pipe insulation is the best insulation.

5) Heating fluid : This is present in case of flat panel systems. In flat panel systems, water is not moving in panels. Its this liquid that moves in panels, and goes into water tank to heat the water.

That liquid required topping up on regular intervals. Now if you do not want to use that liquid, you can put in distilled water also. But distilled water will need topping up more often. Just before replacing our earlier flat panel system due to internal leaks, we had poured in mineral water. At our home we have RO system and took water from that, filled in solar geyser. It worked well, so well it made us think again whether to invest in another system or not.

Note that this is not possible in large systems that you want to install and you will need a large quantity of mineral water.

6) No. Thin chance. But we are losing on heat due to long pipe that runs almost open for a relatively long distance.

I am not very sure about vertical installation, but they are offered. We were told that its not very efficient and secondly we dont have high requirements. But after looking at inefficiency of this system, I gave vertical tube geyser a second thought.

If water channel is there at the end of the vertical piping, do ask if that requires insulation or not.

7) Although they claim it to be so good, my experience says other way round. The flat panel system, till it ran, was a luxury feature. Hot water running almost 24 hours. This vaccum system has reduced this to only one bath system between 5:00 pm to 10:00 am. In between 10:00 to 5:00 more than 3 baths are possible but only with some spacing in between.

This could be due to heat loss, but at the end of the day, we are not satisfied with vaccum tube system.

Do not go by what things say on paper. I think you have Aveo, that was never considered to be the best in its segment overall, but is good enough for you I suppose.

Check out latest designs in this. It will take time before you finalize, show them where you want to install. Sometimes they ( who sell geysers ) can give good advice.

I am not happy with vaccum type, but note that piping is without proper insulation and run quite a length.

EDIT :
Both of our systems were brought from :
http://www.nrgtechnologists.com/
They are quite honest and the people they employ ( i.e. those who come at your place to do installation, servicing, etc ) are general good.

[deky]

Thank you for the responses, I have invited a few dealers here next week to come and have a look and then suggest me the best option with the best price. Lets see what they have to say and then I shall revert back.

As of now I am open to both the evacuated type and the flat panel type and will only take a decision after consulting the technicians. Also I have decided not to convert all the 15 bathrooms to solar heating, but will be starting with 6 and then increase after checking out the performance.

Will keep on updating as decisions are mede

Thanks & regards

[sandeepmdas]

@aaggoswami, I think the first the foremost reason for the inefficiency you are experiencing in the system is the horizontal layout of the EVCs (evacuated vacuum tubes).

I am using a Sintex EVC system in my new house, since Aug 09. Although the climate is different here (in Kerala, near Trivandrum) I can say that the system is perfect. Mine is 100-liter system with 2000W power backup (never connected). I sourced it for Rs.18,500 with the installation, plumbing and a good quality non-return valve costing 1500 extra.

Some points:
1. the collectors should face South.
2. a high quality non-return valve is a must. If this valve fails, there will be a major problem with the hot water seeping thru cold water plumbing and possibly it can destroy normal grey PVC pipes and joints.
3. a 25-degree incline is minimal.
4. unlike flat panels, you can change individual EVCs. You can also run the system with a failed EVC removed, as a stopper is provided to fit in that slot.
5. the other 2 leading companies selling EVC in Kerala are V-Guard and Sudarsan Saur. Goodsun sells flatpanels.

Read more on EVC and installation here:
Types of Evacuated Tube Solar Collectors

[sudev]

@deky: others have covered most of the topics.

Ventilator pipe is to let out any air / steam. Even in a typical house hold you will see vent pipes in plumbing. This ensures that there are no "air locks" and water "hammering" is avoided. If air lock develops without any vent pipe it can cause water flow to stop.

It has to vent at higher level to feed tank simply because otherwise water will flow out due to fluid level equalisation!

I will post some detailed pictures but I see from pics of sanddepmdas that there is no cover glass on top of vacuum tubes. I think this can cause two problems:

One it exposes vacuum tubes to breakage risk
Two it results in decreased efficiency as tubes loose heat with air contact.

[richie4u]

hey all, I am a dealer and distributor for solar water heaters of many brands so if you got any questions please feel free to ask.

@sudev: Well in vacuum tubes or ETC type of solar water heaters there is a possibility of tubes to break but I suggest the customer to install a strong mesh structure (just like in aaggoswami's pictures) just above the tubes only for those areas where there is a possibility of tubes getting broken. Also regarding the efficiency I have personally tested the heating quality to be much higher as compared to flat panel water heaters.

[deep_bang]

hi guys,
I am going to install a Solar heater for my house, and need some help here.
The house is still being constructed, and as such i have a lot of flexibility now.

The root of the problem is as i explain now: We want to install a shower panel that has a few jets in it, and apparantly, this needs a pressurized pump for it to work well. The pressurized pump would be installed near the over head tank, so there is one pump, and all applications that need pressure would use the pressurized line and others would use the normal line.

Now, my plumber says that, since the shower panel would have cold water pressurized, it would also need the hot water to be pressurized. So, this would be done by connecting the pressurized line to the inlet of the solar heater - which in turn provides the pressure on the hot water line too.

Now, my plumber also says that to do this, a regular water heater will not do, but we need a specialized water heater that can take the extra pressure. Is anyone aware of this specal type? Is it available from reputed manufacturers like Anu solar etc?