Solar Space Heaters

[Somdin]

Ive seen lots of different designs for Solar Space Heaters
Lots of things that could keep me busy in my shop for hours and give me some heat on sunny days in the fall/winter

But all of them seem to have one thing missing and Im wondering if anyone has seen this problem solved

What do you do in the summer when you dont want the heat in your house? Simple answer seems to be close the intake and exhaust vents but I would think it would overheat the collector with no where for the heat to go

Has anyone seen a design for a solar space heater with a vent for the outside?
Any Information would be Great
Thanks

[jaskiainen]

Hi Somdin!

Easiest way might be covering your collector during summertime.

[Somdin]

I supppose a good set of shutters would be a good way to cover it up so that the sun cant heat it up

But I wonder whatto do about on the inside for when the sun doesnt shine
would a simple baffle in the duct be enough to keep cold air from coming in or would you need something that sealed better

[Bruce S]

Somdin;
Depending on how much your setup uses fans to distribute the heated air. A small flap acting as a baffle may only be what you need.
Some of the DIY units have used a baffle/flap on both sides
 1) So the hot air comeing in doesn't back flow at night and 2) So the cooled A/C air doesn't get warmed up in the summer.
The weight of the baffle/flap will be determined by the force of the air coming out/in.
Hope this helps
Bruce S

[rossw]

The weight of the baffle/flap will be determined by the force of the air coming out/in.

I don't know if they're still readily available or not, but years ago we had exhaust fans that mounted in walls or windows. There was a decent size fan, but it also had a set of louvers that snapped shut to almost completely seal the thing off. When power was applied to operate the fan, a small solenoid operated the louvers which then swung about 90 degrees to be inline with the airflow.

They were not very expensive either, as I recall. Around $50 for the whole thing.

[Somdin]

Im more concerned with the unit overheating on the outside durring summer months
covering it is low tech but would perform well I think
i also wondered about a vent of some sort that could be opened in the summer

[birdhouse]

have you thought about putting the heater under a deep eave.  this way it would be naturally shaded when the sun is high in the sky (summer) and get full sunlight when the sun is lower in the sky (spring/fall/winter).  you could also mount a solar panel hooked to fans in the same location.  thus it would only turn on the fans when the sun is low enough to hit the whole rig during the cold month.  just an idea i've pondered.  kind of like passive solar heating with purposefully placed windows. 

adam

[TomW]

have you thought about putting the heater under a deep eave.  this way it would be naturally shaded when the sun is high in the sky (summer) and get full sunlight when the sun is lower in the sky (spring/fall/winter). 

adam

You could accomplish the shading with a simple awning, too if the eves are impractical.

Just tossing that on the pile.

Tom

[GaryGary]

Hi,
If the collector is vertical and mounted on a wall, it won't overheat.

The sun is so high in the summer that the radiation on a vertical collector is by a factor of about 2.5 compared to mid winter. 

This is the vertical collector I use:
http://www.builditsolar.com/Projects/SpaceHeating/solar_barn_project.htm
mounted on a south facing wall.
It never goes above 185F, which is fine.

I actually included provisions for venting the collector in the summer (holes in the top and bottom sills that could be uncovered for the summer to let a little air flow through the collector), but I've never used them.

If you do put the collector under an eave, be careful to not overdo it.  The eave may provide more shading than you want in the spring and fall.  There are a couple good tools here: http://www.builditsolar.com/References/SunChartRS.htm#Overhangs  that allow you to see what a given size overhang will do.  If you heat only in mid winter, then you can have a pretty good eave without hurting heat production, but if you have a LONGGGG heating season like we do, you have to be careful about not overdoing the eave.

Gary

[HenryVG]

My collector is vertical, mounted to the wall. The 'house' air flows behind the center surface. In this house air space I put a vent (pvc pipe) on the top of the side and on the bottom (these correspond to the intake and outlet areas going through the house wall) with screens on the inside to keep out insects. During hot months I take off the caps and let the hot air vent out. Then plugs of insulation go in and the caps go on in the fall. Not sure if it's necessary, but then no heat comes in during the summer.