Science Buddies: "Ask an Expert"

We have build the solar room heater but the temperature between the output and input vents stay almost the same or maybe 2 degrees difference at most. Is that what is expected.

Should I be closing out the bottom vents with duct tape. The photo in science buddies site seems that way. We haven't closed the bottom vents but wanted to know if that is the problem.. Ther eis the plastic flap on the black side (outside) output side and there is plastic flap on the inside (non black) (input) side.

The indoor/outdoor thermometers are much bigger than body temperature checkers. Not sure if that is the issue. I am pointing the lower side of the thermometer in the vent.

Thanks.

Hi sciencepk,

Based on the procedure, the vents shouldn't be taped completely shut; otherwise the heated air won't have a way to get out. The plastic wrap should drape over the vents. To get the best results, it will be critical to have all of the edges of the cardboard tightly sealed to the window so that air can only get in and out through the vents.

The temperature increase will depend on many factors, so there isn't one "right" or "expected" increase. The heater will work best on a sunny day in a window that gets a lot of direct sunlight. If the window doesn't get direct sunlight, then the temperature of the room will not increase as much as it might otherwise. A two degree increase in the temperature of air between the intake and outflow vents sounds reasonable to me. If you are worried that the size of the thermometer is affecting your results, you could leave the thermometer in the vent for a longer period of time (perhaps 5 minutes). That might make a difference, or it might not. If you do change how long the thermometer is in the vent, make sure to be consistent in your measurements.