Thermosiphon Wall?

[Griff]

I'm going to add a sun room to the walk-in basement on the south face of my house, possibly as soon as this summer. I'd like to build a thermosiphon air collector into it to take advantage of clear cold days to heat the floor above. The linked page has a version very similar to designs I've seen elsewhere. I don't want to use up my whole wall since a sun room lets in well... the sun. So I thought I'd throw it to the Dwellars for design/material refinements. I'll be placing a pellet stove along this wall for zone heat. I intend to build with fieldstone for the first couple feet but haven't worked out the height of the front wall yet. IDEAS?

[xoxoxoBruce]

Hire 3foot.

[Griff]

He's too slow!

[footfootfoot]

ouch

[Griff]

he he... you may want to compare your progress to mine, I've been on my project a looooooong time.

[BigV]

Idea/question.

I read the article and I agree that capturing the radiation can heat the surrounding air. But if you wish to maximize the effect of the heating, why would you heat cold outside air instead of warmer inside air? Also, I would be very leery of chopping holes in the wall, *especially* to the tune of "...50% of the area of the collector is optimal..." Yikes.

So, I have a suggestion. Just as you can alter the airflow in your car from fresh to recirculate, why not consider making this design recirculate instead of fresh? Imagine this design viewed from the side. The letter S describes the path of the air where the intake is at the lower left hand corner, rising as it's heated to exit at the upper right and corner of my micro-ascii diagram. Imagine the new design following the path of the letter C instead. Now the house, still on the right hand side of the letter feeds the collector from the inside at the lower right hand corner, rises and reenters at the upper right hand corner.

I can see one potential problem here. Since the temperature difference between the air at the bottom of the room and the top of the room is likely to be less than the temperature difference between the bottom outside air and the top of the room, the vigor of the siphon could be less. I wonder though, if that would be offset by not having to heat the much colder air much more to make it "room temperature".

Another thought. With this program, you still have to chop holes in the wall. Yippee.

For that matter, what is the whole reason for this collector/project (the one the guy wrote up and yours, for that matter)? To make a passively powered air circulation system? If so, bravo. Very elegant. Or is it to heat the room? For that, why not just make a stinkin window? Wouldn't that collect the same amount of solar radiation? And give you a view to boot? You'd effectively be living in the collection space where he hung the black screens... where the air is warm.

What are you seeking, Griff?

[Griff]

I'll go look at his design again. The design from Mother Earth News that I looked at uses recirculated air. My basic goals are to warm the floor upstairs and make a nice sit down space/solarium. I may just use darker heat absorbing materials in the sunspace but the thermosiphon has a simplicity that is just attractive. Heat losses through windows are higher but I could add insulated window shades for nights. The idea is probably better for heating water and workshops. Thanks for the input.

[BigV]

How can there be heat losses through windows but heat gains through thermosiphons? I think there's some apple/orange hybridization going on here...

What about double/triple paned windows? We have those and I love them. No condensation, and lower heat bills.

[Griff]

I'm assuming that the thermosiphon being in front of an intact stud wall would radiate less heat out. Triple pane is probably the best answer though.

[xoxoxoBruce]

Originally Posted by BigV

I can see one potential problem here. Since the temperature difference between the air at the bottom of the room and the top of the room is likely to be less than the temperature difference between the bottom outside air and the top of the room, the vigor of the siphon could be less. I wonder though, if that would be offset by not having to heat the much colder air much more to make it "room temperature".

The "vigor" is governed by the amount of heat the system adds to the air in it. The bottom "suck", will be the same whether it's sucking inside or outside, so yes, sucking from the inside is much better unless you need fresh air.