Hot Air Solar Collector

[winter]

Your Solar Home

Solarsheat 1500G

Glazed Hot Air Solar Collector

Cost is $1,550 plus shipping at  altenergystore.com

Seems expensive. I can find only 2 sources here in USA to buy, (Question #1) are there discounters for Solarsheat items?

Also, other than build my own, (Question # 2) are there are less expensive sources for Hot Air Solar heating units with this high quality (Glass and forced air with internal power)?

[willib]

The lack of sellers for hot air systems is probably due to the ease of making such a system..and anyone going to the trouble to install such as system himself would probably go the extra step and fabricate it compleatly.

[dudevato]

Here's some 'solar heating' links that I've saved:

http://www.fieldlines.com/story/2004/9/20/165658/111  Good Luck

[Aelric]

Check this out:

http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

it is from an article in Home Power magazine about how a man built a solar air heater for his workshop, In my humble opinion it is a very good read :-)

[winter]

Thanks for all the pointers.

If all I want is to warm the house with solar, is the Hot Air Solar Collector (Vrs Water or Solar Cells), the easy/best way to do the job?

[wdyasq]

IMO best is direct heat through window.  Next direct solar heater as on 'build it solar'.  Solar to water requires two heat transfers, first to water, second to air.  Each transfer costs some efficiency.

Solar cells are inefficient for converting light to electricity and rediculous for light to heat.

Ron

[wdyasq]

should read ' Next direct solar TO AIR heater as on 'build it solar'.'

Ron

[Gordy]

Winter,

Most solar hot air collector plans are easy and cheap to build, with the fastest pay back. But will only supply heat to the house when the sun is shining (6-7 hours a day), unless you build a storage setup to pump the hot air thourgh for night use. In the early days they were building insulated rock boxs for heat storage. But some reported that when the system was not in use (summer) the rocks would draw moisture and start growing mold.

The water based collector's are much more expensive to build and install and complicated. But have advantages of multiple desin usages, infloor radiant, air ext. to forced air funace, base board radiant, heat ext. for domestic hot water, ect.

Some will argue against the point of useing windows as solar collectors. But I have 5 south facing windows that I use for collectors (TV room, puter room, unused bed room). The windows have those spring loaded rollup sun blocker shades, to cut glair on the tv & puter screens. In the fall I replace these with ones that I've replaced the white plastic with black plastic. The black plastic was shiney so I used a finish sander/250 grit to remove the shine. Testing showed 3-5 degree's warmer when sanded. "Work's for me to cut gas use during the day"

Now to mount my garage sale mirrors outside to the bottom of the windows, and get more light into the black plastic.

Gordy

[Catch66]

 Just a note to your idea of a solar air heater.Seems to me they are not useful in summer time when the actual heat is HOT and lots of Sunshine in the North country.

 I also have started a Heater of sorts 4'x10' collector which will incorporate a water system as well to take advantage of the summer sun.So will be useful all year not just in the winter.

The termal mass of adding the copper to the absorber plate will also help with winter collection.

 I have been considering this for a while and collecting various parts.Using all 12v blowers from computers 120mm high output cfm fans and will add 12v circulation pump for glycol water solution to circulate through heat exchanger.In time I will purchase a 20 watt pv panel to run all.

 I am considering taking pictures for step by step building.But that is away for some time yet.

 Later,Catch 66

[GaryGary]

Hi,

"Your Solar Home

Solarsheat 1500G

Glazed Hot Air Solar Collector

Cost is $1,550 plus shipping at  altenergystore.com

Seems expensive. I can find only 2 sources here in USA to buy, (Question #1) are there discounters for Solarsheat items?

Also, other than build my own, (Question # 2) are there are less expensive sources for Hot Air Solar heating units with this high quality (Glass and forced air with internal power)?"

-----------------------------

The panel seems well made.  It also seems very expensive to me.

Its around $50 per sqft -- this is very high.  

I'm the guy who built the BuildItSolar collector and wrote the HomePower article that is mentioned above.  The BuildItSolar collector is around 150 sqft (about 5 times larger than the Solarsheat) and cost $350 in materials (and about 3 days labor) to build -- a bit over $2 per sqft.   While the "Solarsheat" collector may put out a little more heat per sqft, the heat per dollar spent well under a tenth of the the BuildItSolar collector.  

The built in PV powered fan is a nice touch, but the thermosyphon design that does not require any fan or PV at all seems more simple and elegant to me.

I would guess that the life of the Solarsheat will be longer -- I don't expect the polycarbonate glazing on the BuildItSolar Collector to last much over 10 years (even though the material is garanteed for "life".  But, replacement of the glazing is not a large or expensive job.  You could also just do a DIY air collector with glass glazing.  

If you need a fan forced air collector, than I'd take a look here for ideas.

http://www.builditsolar.com/Projects/SpaceHeating/SolAirHtSysBook/SolAirHtingBk.htm

This book has tons of good detailed info on solar air collectors -- thanks to the authors (Steve and Andy) its a free download.

More info on DIY collectors here:

http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

Just to add my 2 cents worth on a couple things mentioned in the various good answers you got:

Windows as Collectors:

I'd agree with the person who suggested that windows make good solar collectors.  The collection efficiency of a window during sunny periods is as good a good collector.  The place where windows fall down is that they have high heat losses during the night -- this can offset a lot of the gain they made during the day.  This can be overcome with good insulating shades or shutters.  Windows also have the advantage of providing lots of natural light, which can be nice.

Air Collectors and Storage:

You can use the house thermal mass as storage to some degree.  Just provide some circulation of air such that the heat from the collector during the day can transfer some of its heat to the house mass (walls, floors, ...).  If you let the house get up to (say) 80 or 85F during the day, the thermal mass will then give up heat during the night and reduce the cool down rate of the house at night.

A very rough rule of thumb is that the collector are can be up to 20% of the house floor area with this scheme.  With more collector area than 20%, you need fancier storage systems (eg rock bins).

Water Collectors:

I'm currently working on a solar space heating system for my house that uses water collectors and a water tank for heat storage.  I have to say it is more complex, expensive, and time consuming than air collectors.   I went to water collectors because it was really the only way I could figure out to make the system work.  It seems to me that if you can make air collectors work in your situation, you will save both money and time.

Good Luck on your Project!

Gary

www.BuildItSolar.com

[Dan 04617]

I was in Home Despot yesterday and noticed that they have PV powered attic fans (~16" dia.) with a 10W panel for $180.  That seems about right for adding a forced draft to one of these hot air collectors.

I'm considering building some of these things onto the south side of my house.  The clapboards are shot there anyway, and I'd take it down to sheathing, or maybe further and re-do the insulation from the outside if necessary.  Then I'd build the colectors starting with their frames and an inch of foil faced foam attached to the sheathing boards.  I'm imagining the cheapest corrugated galvanized steel roofing metal painted flat black as the collector plate.

Questions:

What's the difference in efficiency between having the warming air pass behind the metal vs. in front of it, between metal and glass?  

Would it improve heat transfer to paint the back of the metal flat black as well as the front?

I see some 34x76 glass in the want ads, and I don't know if it's single or double glazed.  How badly do I want double glazed, especially if the circulating air stays behind the metal?

Beyond just closing the vents, has anyone thought of covering up the collectors in the summer?  Wouldn't this increase their lifespan?