Thoughts on solar space heating
 

I just recently found this site while researching solar space heating, and would like to thank you guys for such a great resource! I am planning on building a solar hot water heating system, and would like to incorporate space heating along with it. I have read on builditsolar where folks have used radiant floor heating, but I would like to get ideas on other ways to transfer the heat. I don't really have the ability to do radiant floors because I am trying to heat my basement on a slab. I like the idea of a radiant wall, but my walls are already finished. I have considered hydronic baseboard, but would like to stay on the diy side to keep costs down. Anyone else have any ideas?

Welcome to the site Austin.

The reason that solar hot water works so well with radiant floors is because of the huge surface area and the wonders of radiant heat. Solar will work with other forms of distributing the heat, but it just won't work as good because other methods require higher water temperatures. If you want a different form of using that heat you'll need something with a lot of surface area to try to make up for the difference.

Hi Austin,
Some possibilities for efficient ways to distribute solar heat here:
Solar space heating -- active and passive solar projects for space heating
Another option is to go to solar air heaters for the space heating part -- this makes the distribution of the heat easy -- you just blow the solar heated air into the room(s) you want to heat.

Gary

You could use a automotive style radiator with a fan, it will give you a lot of surface area from a small space, there are devices like this that you can install in the duct work of the house as well, I've also seen them in the toe kick of cabinetry.

In most cases, the amount of energy used to heat a house is several times greater than the energy required to heat water. So, usually you would be looking at solar space heating, with solar water heat as a side benefit. So you would size your solar components appropriately, in particular the number of collectors. For instance, if a home could get by with two 4 x 8 foot solar panels to heating domestic water, you might want eight to twenty panels to heat your house... then there's the other two to heat your water.

In your case, since you live in NC, space heating is not as large a burden as it might be in areas with much higher Heating Degree Days, like Minnesota, for instance.

Then there is the matter of soil temperature...


In your case, depending on where you live, the soil temp, at 20 feet and deeper is probably in the mid-60's. It will be somewhat lower than that at basement depth in the winter, but the heating load in your basement is not going to be so terribly high.

One heating idea you haven't rejected yet is radiant ceiling heat. Here's a photo of how it is done in an upstairs room:


You'd want to use aluminum spreader plates for efficiency.

-AC_Hacker

Thanks for all of the replies guys! I have a drop ceiling in the basement, so the radiant ceiling may not work well (or will it??).

Gary, I have looked at the link you posted and really like the idea of a pex radiator, but do you have any feedback on how well that works?

Ryland, I like the idea of a auto radiator or a water to air heat exchanger with a fan blowing across it. Does anyone have any feedback on this?

Again, thanks for the replies guys! Can't wait to get stated!

Storage tank?
 

All right, I am in the process of hunting deals on parts and I have a question about the storage tank. Would a tank like this work for the storage tank?

Link

They are made of Linear Low Density Polyethylene (LLDPE) and are suitable for potable water. My concern is the high temperature. I have sent the company an email but haven't heard back yet.

I like this tank because I found a used 275 gallon tank for $100. They are already plumbed for the inlet and outlet, and have a threaded lid to allow fitting the heat exchanger inside.

What do you guys think?

I'm not certain but I'm pretty sure those tanks can't handle high enough temps to be storage tanks.

I never did hear back from the company. Anyone have any experience with these? After doing some research, it seems there are some applications with LLDPE material exceeding 140 degrees. I'm torn on whether to give it a shot or just suck it up and build a tank. $100 is tempting, but I'd hate to flood the basement:)

low-profile
 

Hi Austin,
The basement heating system that really impressed me was this one..
Low Profile Solar Hot Air Project 1
I loved the low-profile system and it does get some heat down into a finished basement.
I think the visual impact, price and performance is pretty dang good..
You just need some outdoor wall space facing the south.

We have a forced hotwater baseboard downstairs now. Uses too much oil to run.
Recently, I was thinking of adding some one of those radian floor setups to the finished side basement floor,
But, not for radian heating, but to scavenge the 60F slab heat. It's free geothermal heat!
I would cover it over, with an insulated floor. I know that sucking all the heat out of the slab would be pretty quick,
but I think it might recover in a few hours.
It might be good for getting a bust of heat, while I was down there working.
And it might warm back up to 60 overnight.. :)
I have an old 18,000 BTU AC that I'm about to un-install..
It's in good shape, and might be recyclable..

Cheers,
Rich