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Practical solar hot water questions


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I have one for over 5 years now and love it. We always need to add cold water even in the winter and never run out of hot water except during long periods (4+days) of bad weather no matter how often we take a shower or wash clothes/dishes. But we do have a bigger size then advised. And that is what i would advise too, take a size which is considerably bigger then they advise. Otherwise you run out of hot water much more often. Even i would take an even bigger one then i have now (240liters for family of 4) if i would need to get a new one. With current one i ran out of hot water about 3 times in the past 5+ years we have the solar so that isn't bad anyway. And because of that we don't have a gastank anymore (cook is induction). To avoid cold water with shower we now don't use hot water for washing clothes/dishes during longer periods of bad weather and with that we survive the longer periods of bad weather just fine. Even with only one hour of little sun it heats up pretty much. 
But as said the size really matters much, i know others who have smaller ones and they run out of water much more often and need to switch back to gas often even after just one shower.

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Also your choice will depend on presurized or gravity water system. With presirized you have 2 choices.

One uses water in the solar tank, the other uses a copper tube inside the tank through which your water passes and heats by induction. With the heat induction tank you will have hot water longer as you are not limited to the water in the tank.

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We had a 160L Sharp solar hot water pressurized system in Chapala and had a bypass valve system at a convenient, ground level location, so that we could easily switch to the on-damand propane heater.  We never had to; not even when we had guests in the casita.   Go solar, for sure. It will really reduce your gas bill.  We cooked and dried clothes with propane, but discovered that the propane hot water heater was the real hog, using over half the propane until we went solar.

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About a year ago I read about a newer solar hot water technology, a tankless system with a much lower height profile. I recall it's about knee high. I believe some of these systems have been installed locally. Would like to compare systems but don't know of any installers of the new type. 

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For those with rooftop tinakos and gravity feed- I was going to try the following, which seems like a low cost, quick installation time alternative.

Big coil of black plastic tubing on the rooftop fed with water from the tinako. Tubing then connects to inlet pipe on normal gas water heater. Keep water heater turned off until cloudy days when tubing is not heating the water. On those days, light the water heater.

Anyone see any reason this wouldn't work?

If I get around to doing it (my to-do list is miles long) will let you all know how it works.

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I tried it once just to fill a kid's pool with water which was OK as it warmed it enough to don't get the kids too cold. But it won't work that well for things like getting a shower or washing clothes. First you need to get an insane amount of tube to get enough hot water and to heat it up fast enough to make it usable for showers and washing clothes. And if I remember correctly I think it loses pretty much pressure because of the length of the tubes.

During the months like April and May it might work but otherwise it is nowhere near practical. Besides that, the main problem is it will start losing all the heat already before sunset and you won't get hot water again until at least several hours after sunrise. So you will only get warmer temperatures a few hours during 12-5pm or so. Those aren't the hours I normally get a shower.

A good insulation is really important as you don't need to reheat the water from a low temperature each day. Each morning I still have way too hot water because the tank of my solar heater hardly loses any heat during nights and because of that after several days (like these past few days) without sun I still have hot water.

Just spend a bit more money in a good big solar heater and you will win the money back in no time anyway and you won't need to use gas heaters anymore with maybe a very few exceptions.

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Bought a Thermosol from John Rafferty of Chapala several years ago.   Got the largest size.  Hooked it with the gas heater should I need more.  Never did.  Propane consumption cut to less than a tank a year.   I' m sure a formula exists to ascertain your likely consumption of tank heaters just apply that finding to size of solar water tank.    About the only problem I had was too much hot water which is then discharged via the relief valve so you need to run a small hot water pipe to an area where pets or people won't inadvertantly get splashed.

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11 hours ago, mudgirl said:

For those with rooftop tinakos and gravity feed- I was going to try the following, which seems like a low cost, quick installation time alternative.

Big coil of black plastic tubing on the rooftop fed with water from the tinako. Tubing then connects to inlet pipe on normal gas water heater. Keep water heater turned off until cloudy days when tubing is not heating the water. On those days, light the water heater.

Anyone see any reason this wouldn't work?

If I get around to doing it (my to-do list is miles long) will let you all know how it works.

You would need hundreds of meters of black hose, and 20 minutes after sunset it would be cold. A solar heater uses UV radiation collected in gas filled glass tubes with a copper element to heat the water in the tank. The tank is stainless steel inside insulation and a tank outside painted or stainless depending on price. It is like a giant thermos bottle. The water in the tank is usually very close to or actually boiling. 

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On 11/12/2016 at 9:43 AM, Constance said:

This is such interesting information!  I am looking for a new hot water heater, but know nothing about solar heaters. Would one of you be kind and give info about different brands available here at lakeside?

 

thanks! 

You can check on Mercadolibre for calentadores solares change your search to Jalisco and there you can see many brands and prices. Remember with a tinaco it is gravity feed  feed and a lower price.. For a pressurized water system you need alta pression. For a 2Br house suggest minimum of 200 liters and 15 tubes.

Most of the GDL sellers will deliver lakeside for minimum cost, and many offer 12 months interest free if you have a Mexican ccard. Any good plumber here can install. 

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20 hours ago, Constance said:

Thank you, Mostlylost, for your advise. I will do my search to Jalisco and hope to find some name brands.

 I would love to hear from Ednet94, when he writes about getting a "good big solar heater", which one did you buy and have used for the past 5 years?

I'm not sure as the letters on the solar are already faded away but i think it is Solar Technology of 210 or 240 liters. http://www.solartechnology.com.mx But as said i would buy even a bigger one if i would need to get a new one. I bought mine at Ferreterias Calzada which are all over Guadalajara. Not sure if they still sell them though.

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Here's a link right to the (english) solar water heater page, to save you time:

http://www.solartechnology.com.mx/calentadores_solares_agua.php?sl=en

No need to go to Guad, or anywhere, the tech will visit your home to check it, and then you can have the system delivered & installed.   EZ-PZ.

24 tubes / 280 liters is  a great size, while more than most 2 pp h/h need on a daily basis, it has the extra capacity to handle houseguests, a couple of days without sun, and / or things like filling a tub on a regular basis.     The largest stand-alone system is 30 tubes, 340 liters.

 

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