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Solar Thermal Capture Tubes - Frequently Asked Questions


How many tubes are necessary for the average home (let's say 2000 square feet, for the purpose of discussion)?

The Number of tubes needed for heating depends on the heat loss v heat gain of the structure far more than Square Feet. Factors like the insulation R-value, the window sizes and type how tightly sealed or drafty ETC mean far more than size alone. Lighting and solar gain windows with night insulation can add a lot of heat gain. That needs to be balanced against heat loss through the insulation, and due to drafts, windows, and doors, especially at night.

http://www.ornl.gov/sci/roofs+walls/insulation/ins_03.html
http://www.ornl.gov/sci/roofs+walls/
http://www.eere.energy.gov/buildings/tech/hvac/
http://www.eere.energy.gov/buildings/tech/lighting/
http://www.eere.energy.gov/buildings/tech/windows.html
http://www.eere.energy.gov/buildings/tech/enveloperd.html


Solar can usually be integrated with the free thermal resource of the deep ground to create an alternative energy strategy that allows for the development, implementation, and deployment of true, zero-fuel energy building designs that require no fossil fuels at all.

The deep ground resource in VA varies between 55°F and 63°F so you want to use as much of that free resource as possible for heating and cooling your buildings. Then, only a small amount of added solar gain is needed to heat and store enough hot space heating water (for around the clock heating from a 8 hour solar day) to add about 20°F to the free ground resource temperature. To extract all that free heat from the ground beneath us we use a closed loop U-tube that requires no pumping power ad that removes no groundwater from any aquifers.



How many tubes would I need for my house?

For Domestic Hot Water (DHW) typically 10-25 tubes will suffice depending on how many people use the system and the size of the storage tank (Many people install a 50-60 gallon solar pre-heat tank in addition to the existing DHW tank)
It would also depend on use. Is the solar system used just for hot water for bathing, etc…..? or also to heat the house (radiator system)?



I'm also unclear about what is involved in the installation, and exactly where the tubes come in. Is that something I can do myself, or do I need to hire a plumber?

If you can sweat solder copper pipe and do the work yourself, you can save the instillation expense.

http://www.easy2diy.com/cm/easy/diy_ht_3d_index.asp?page_id=35749917
http://www.umass.edu/classes/eng351/examples/pipe.htm
http://www.misterfixit.com/nosweat.htm
http://www.doityourself.com/stry/cutjoincopperpipe
http://www.copper.org/applications/plumbing/techref/cth/cth_main.htm (Copper Tube Handbook) PDF, chapter VI)


Fossil Freedom can provide some plans for do-it-your-selfers.


It is pretty straightforward……

http://www1.eere.energy.gov/solar/solar_heating.html
http://www1.eere.energy.gov/solar/sh_basics_water.html
http://www1.eere.energy.gov /solar/sh_basics_collectors.html
http://www1.eere.energy.gov/solar/sh_basics_collectors.html#evacuatedtube

The quickest return would be to install solar Domestic Hot water, because after heat, the hot water and cloths dryer are the most energy intensive. Hot water is used year round and quickly saves a lot of money.

 

 

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