BIG project Solar tubes to heat Pool And Garage

[mtmtntop]

also, this is an interesting website i found. i never did get answers to my questions to him but there is alot of data on this website. It shows a flat plate and evac tube array side by side on his roof in ny , i think it is.

http://cwc-das.com/wcsd//tabs.php?loggerids[]=485E700680A6C389

there are alot of variables that can affect these readings though. like how the controllers are set. given all the work he has gone through, i assumed everything was equal.

[armstrr]

Thanks for the reply and info. yes, the more i look into this, the more i see that each system is impacted by MANY environmental/setup factors that makes sizing very difficult.

I'm ok with that. my plan at this point is to make the system somewhat modular. Since my garage shop and pool technically do not NEED to be heated, any heat added is a bonus. Many sites that do make recommendations for pool heating suggest the square footage of solar collectors to be 40-50% of the pool surface. (in my case that would be 400sf!).

At this point, since there are diy methods of making good flat panel collectors using prefabed fin tubes, i'll likely order enough fin tubes to do 400sf or close to. i will probably start by building about 1/2 of that and see how it goes for both the pool and shop. if more is required...add more. if it is ok, sell the remaining fin tubes.

since my goal is not to have high temperature thermal storage, but rather to dump all available heat to the pool or cement pad, this should keep the collector inlet temps low...thus increasing the collectors efficiency.

that's where i'm at so far. City council has sent out letters to my neighbours regarding my requested height and squarefootage variance. I should find out in 2 weeks if i can move forward!

I have been walking my yard taking note of the sun's angles. i'm hoping to put the shop on the south side of my lot...but that puts me close to my neighbours 18' pine trees. they are crowed, so i do not believe they have much more height growth. my roof peak is 20 feet. i likely will either go with 6 foot long collectors or 8 foot that protrude past the roof peak...otherwise those pines are gonna rob me of winter sun. dang. i'll check the shadows the middle of dec, since that will be the worst case.

[armstrr]

i am also weighing the pros cons of a drainback system vs a closed system. domestic hot water is not involved, so that should make it a bit easier.

i was thinking that i could build an insulated storage tank approx 300gallons integrated into the floor. the collector pump could drain/pump into this. i could set up the circulator pump for the radiant floor to pull directly from this. in the summer, for the pool, i would think i could use coils of copper tubing placed into this sump for the pool heat exchanger??? or is copper compatible with pool water? is there another type of exchanger that i could places into a this tank that would work better/be more compatible with pool water?

thanks guys

[mtmtntop]

i am using only stainless steel heat exchangers. the thing with copper and pool water, or hot tub water, is that the ph can change alot based on the people using it. you need to check it all the time, especially if you use any copper. when we had a hot tub, we had certain friends that always made it go acidic. low ph water will quickly eat up copper plumbing. here is a trick to use if you want to go with copper plumbing involved with the pool water. put a penny where you can see it in the pool. if it is shiny, the ph is too low. i assume you will be using pvc to plumb the pool and just copper for a heat exchanger. everything for pools is either 1 1/2 or 2" so you will have to connect to pvc at some point. my heat exchanger is plumbed for 1 1/2" pipe for the pool loop and 3/4" from the panel/boiler loop. with this setup the pool will take 10-12 degrees from the water temp as it passes through the heat exchanger.

[armstrr]

are you using a commercially availavle stainless plate exchanger? or a tube in shell? what make/brand did you go with?

obviously i am not set on using anything yet...my thought on the copper was just that it is a good conductor, is readily available in coils and is easy to work with. thanks for the penny trick. that could be of great help if i do go the copper route. i am envisioning a copper header with multiple take offs each leading to a coil of copper. i imagine several coils would be required to minimize pressure drop. on the other hand, for efficiency sake i plan to use the absolute smallest horsepower pump to filter the pool. that will save on electricity and allow continuous filtering at low pressures during the daylight hours.

thanks! keep the ideas/suggestions coming!

[mountain]

We grappled with all of these same questions for our house. We are not wealthy & the system cost had to be affordable. Actually result in reasonable payback.
We elected to build a hot-box that heats air directly, which is then fed into our basement where energy harvested helps heat the entire house. There is no mechanical equipment for the house aside from a 4" 12VDC fan. It works well beyond our wildest dreams. Today (Dec1), was a cold clear Canadian bluebird day, and the thing harvested 6.6 kWh (fantastic for 2.2m2 window area). Efficiency is high because the box is very well insulated & there are minimal losses.

Come this summer, The hot-box will house water-heat collector, which will directly heat an above-ground pool. No need to complicate mechanical systems by sharing pool/house heating systems . One common multi-use collector structure does it all.

https://www.mountainelectric.ca/hotbox

[armstrr]

We grappled with all of these same questions for our house. We are not wealthy & the system cost had to be affordable. Actually result in reasonable payback.
We elected to build a hot-box that heats air directly, which is then fed into our basement where energy harvested helps heat the entire house. There is no mechanical equipment for the house aside from a 4" 12VDC fan. It works well beyond our wildest dreams. Today (Dec1), was a cold clear Canadian bluebird day, and the thing harvested 6.6 kWh (fantastic for 2.2m2 window area). Efficiency is high because the box is very well insulated & there are minimal losses.

Come this summer, The hot-box will house water-heat collector, which will directly heat an above-ground pool. No need to complicate mechanical systems by sharing pool/house heating systems . One common multi-use collector structure does it all.

www.mountainelectric.ca/hotbox

Yes, I read your write-up on that hot box last week. it looks excellent and sounds like it works even better.

so you will have an outdoor and indoor pool this summer?? what size pool are you planning on heating with it?

[mountain]

Just 1 small above-ground outdoor pool (sun-tub). Summer use only, once we won't need the heat from the hotbox for the house, may as well heat the sun-tub nice & warm.

I could tie-in to heat domestic water, but to be realistic, the $payback would be a thousand years. An end-of-day dip into the sun-tub will replace the otherwise needed shower.

[armstrr]

well, my city's "committee of adjustments" turned down my proposed 19'8" peak height and limited me to 16'4", so now i think my neighbour's evergreens to the south will partially block the panels during the winter.....unless i raise the panels above the roof....

what is the easiest way to determine if these shadows will interfere? i can measure the trees, and i know where the the building will sit, but just eyeballing it (before the building is up) seems difficult at best.

[mountain]

use the NOAA link solar calcultor

http://www.srrb.noaa.gov/highlights/sunrise/azel.html

create a table (I've attached the one I made for my home at latitude 50 DegN)

Use a builders level, one that has an altitude protractor built into it. Just sight along the set angle. Failing that, borrow a transit.

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or, just look where the shadows go on Dec 21

But, as my wife points out, it is my personality to first choose the most complicated method.