solar hot water size need

Putting in solar hot water in the house. Two bathrooms, two people looking at 160 liter system but wondering if it is enough hot water. The 240 liter is $350 us more than the 160 liter system. The larger unit would carry more hot water into the morning hours and the fuel is free. I wonder though is it needed. I would hate to waste $350 on over kill by getting too large a system. What are your experiences? Do you run out of hot water or is 160 liter enough?

Thanks Bill

I don't have solar hot water, but just looking at it by gallonage, what happens if you have guest or a few cloudy cool days? I think a qualified plumber should be able to answer your question. Personally, I would spend the extra 350 US.

I have a 160 liter system. With guests or more than two cloudy days in a row it's a stretch. I'd opt for the 240.

Bill, just curious, what is the total cost of both systems you are looking at?

$1250 us for 160 liter and $1600 us for 240 liter which includes installation

Not bad. Did you do a analysis to determine what your pay back time will be?

We use a 300 liter tank approx in 3 months or 240 to 250 liter depending what the gas guy leaves for gas vaporization. We use the gas only for cooking and hot water so it is basically for heating hot water. We also turn the water heater to pilot when not using for hot water. The hot water heater is a one year old high efficient 36 liter cal-o rex. I figure I will still use one tank a year for cloudy days,etc.. The pay back for me is a steadier source of hot water and 3 1/2 to 4 1/2 years in gas expense if the price stays at today's rates.

The cost break even for the unit is 3 1/2 to 4 1/2 year on the 160 liter unit.

Thanks Bill.

I suggest you get more bids, $1250 seems high to me.

I was told by E2 Energias that they two systems. One for gravity systems and one for pressure systems. The tank on the pressure system is much thicker walled and costs more. The tube system or the panel system were the same cost. The 160 gravity was approx $1000 us or $200 cheaper.
The hardware next to Guadalajara Pharmacy wanted approx $500 US for gravity feed with one year warrenty and $900 for pressure system solar water heaters with 10 year warrenty. The gravity unit was 160 liter with the tubes and the pressure system was 160 liter with solar panel.
I didn't check with ESun energy because I assumed they were electrical only and not hot water. I don't know if I assumed right or wrongly so it could be a place to check.
I am still in the research part of this project so if you have a suggestion of where else to check it would be most welcomed.
Thanks

The hardware was not installed and E2 Energias was installed at the price quoted.

I was recently told, by a local plumber, that the average shower uses 32 liters - hope that helps!

There are several important issues. First, do you really want to have a very large system installed that will take care of the cloudiest day when you have the most guests, or might it be smarter to buy a smaller system, one that has more than enough hot water 90 to 95% of the time, thereby allowing you to purchase a much smaller system taking up less roof space. That is the choice I made.

So what do you do when you have all kinds of guests and it's been cloudy for several days? Well you also have a small instant on gas fired hot water heater installed that uses electricity for ignition and therefore doesn't use gas to keep the pilot light lit.

Also try to place the hot water system as close to the largest hot water user you have, which is probably the shower/bath and/or Jacuzzi. Also remember to insolate the hot water pipes so that they wont loose heat to their surroundings.

I had my system installed 5 years ago and have almost never needed to use my instant on. And boy do the insolated pipes delivering the hot water make a big difference

Whom did I use to help design my system as my house was rebuilt? I read the forums learning the basics on line and then finally checked with my architect.

I would guess that the photo-voltaic offices could also recommend a good person to learn more from about sizing prices, etc.

Good luck.

Postman,

You can find answers about solar related topics at this sight: www.builditsolar.com. If you are a handy person (political correct term), you can build your own. I have been giving this subject a lot of thought as my wife and I plan to retire there in a few years. A simple, batch heater, should work very well down there as you do not have freezing weather in Lake Chapala

I believe those prices are a bit high as well, I was just at Ferreterias Calzada in Chapala and they quoted me 6650 for a 180 liter gravity fed system, and 7900 for one that can handle a pressurized system. – And the installation fee was not a lot, around 800 pesos for the labor, not including any supplies that may be needed. (they had a sale on the 120 liter system, only 4450 pesos.)

And I've heard that a normal shower takes around 40 litres of hot water, - about two 5 gallon water garafons. But the water in solar heaters usually comes out hotter than a gas water heater so the hot water stretches further as you have to add more cold water. Personally I think a 160 liter system is enough, or better yet a 180 liter system like this one.

And like Pete says it's important to insulate the pipes and locate it near the main bathroom. It also needs to be in a certain direction according to the sun, but a good installer should know that.

I think solar water heaters are well worth the investment, especially as they have gone down in price in recent years and the price of propane keeps going up.

Slightly off topic...
The house we are renting has solar hot water but I have never been up on the roof to see it.
Do these units need servicing on a regular basis? I am asking because the water is so hard here that I am assuming that there must be some kind of build up of scale. If it does need servicing, say once a year, who would you call to do it. TIA.

If it is a newer system that uses round tubes then as far as I know they are basically maintenance free, but it would be good to check with an expert.

And Ferreterias Calzadas uses a brand of solar water heaters called 'Solar Technology', they have a good website in both Spanish and English, on this page there are some 'tips': http://www.solartechnology.com.mx/tips.php?leng=EN

I thank all for the responses and realize I have more work to do.
The hard water question made me think of the E2 Energias answer to hard water. He recommended I put an ionized rod in the tank yearly and just leave the old rod in the tank. The rods attract calicum,etc.and take care of the hard water. I am planning to stay here for the long haul. Putting a rod in the tank every year with the old calcified rods still in the tank I will be back boiling water on the stove in no time.
Thanks Kiwifruit for the suggestion of Ferretrias Calzadas as another source for the water heater. I will also have to calculate the material cost to run a supply line to existing line suppling the present water heater to compare apples to apples. I have an older home and it shouldn't be too hard to figure. I also have to check on what is included in the E2 bid also. The pipe insulation on outside pipes is a excellent heat saver.
I like David P's suggestion of the larger unit. We come from near the northern end of US I-35 and have a lot of friends and family that are planning visits for the next year or two. Calculating between the water hardness and the novelity of visiting Mexico here fading; the hard water scale buildup on the interior of the tank will make it the smaller tank and just right for two people in a few years.
I thank all for the great suggestions and websites to check. It was a great help to me in my quest for a green source of hot water. Any more ideas would be apppreciated.
Bill

The Postman wrote: I thank all for the responses and realize I have more work to do.
The hard water question made me think of the E2 Energias answer to hard water. He recommended I put an ionized rod in the tank yearly and just leave the old rod in the tank. The rods attract calicum,etc.and take care of the hard water. I am planning to stay here for the long haul. Putting a rod in the tank every year with the old calcified rods still in the tank I will be back boiling water on the stove in no time.
Thanks Kiwifruit for the suggestion of Ferretrias Calzadas as another source for the water heater. I will also have to calculate the material cost to run a supply line to existing line suppling the present water heater to compare apples to apples. I have an older home and it shouldn't be too hard to figure. I also have to check on what is included in the E2 bid also. The pipe insulation on outside pipes is a excellent heat saver.
I like David P's suggestion of the larger unit. We come from near the northern end of US I-35 and have a lot of friends and family that are planning visits for the next year or two. Calculating between the water hardness and the novelity of visiting Mexico here fading; the hard water scale buildup on the interior of the tank will make it the smaller tank and just right for two people in a few years.
I thank all for the great suggestions and websites to check. It was a great help to me in my quest for a green source of hot water. Any more ideas would be apppreciated.
Bill

After living here for five years I would remove the excess minerals (water softener) rather than try to live with them. Folks here who do the cleaning
will tell you that you can probably pay for the system out of the bill for CLR down here. It will help your glassware and I do get tired of scrubbing down
the sinks here. Get rid of the minerals rather than leaving them in would be my suggestion. When you soap up you really can see the difference and
why put all those minerals into your pipes and tanks of your new system. I know the level of minerals vary here but in baja ajijic its pretty bad. Houses
with water softeners are pretty nice.
Z