Hi,
Probably the best way to use water heated by solar collectors for space heating is with a radiant floor (ie slab with embedded PEX tubing). This allows you to heat with water that is relatively cool (say compared to radiators) -- solar panels are more efficient (produce more heat) when used at low temperatures.
These are some good links on designing and building a solar radiant floor:
http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm#Active
The very first article by Guy Marsden is a very detailed description of his solar radiant floor system. The HouseNeeds site has a variety of radiant floor solar heating diagrams with various kinds of backup heat.
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It sounds like you are thinking of mounting the collectors on the south wall?
The vertical wall mount is good for winter space heating, because the sun is low. If your climate is such that there is frequently snow on the ground, then you get an extra bonus with the wall mount from the reflection off the snow. For year round heating of water for showers etc., mounting the collectors at an tilt angle about equal to your latitude provides the best year round performance. But, with that much collector area, you would still get a lot of hot water in the summer with the panels mounted vertially -- just make sure the roof overhang does not shade the panels in the summer.
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You have lots and lots of square footage, and unless you live in a mild climate the 8 collectors are not likely to be enough to provide a large fraction of your heat. Have you thought about using some of that south wall for some simple thermosyphon air collectors? These are cheap (as little as $2 persqft), and provide a lot of heat.
This is the one I built for my shop:
http://www.builditsolar.com/Projects/SpaceHeating/solar_barn_project.htm
You can also incoroporate direct gain windows in the south wall. These would be just as effective in collecting solar energy as commercial collectors are. But, they should have some form of insulation at night, or the losses are large. The nice thing about the windows is that you get lots of light. There are a few on my space heating page:
http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm
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If you want to check out those panels before you install them, here are some things to look for:
http://www.builditsolar.com/Projects/WaterHeating/UsedCollectors.htm
Gary