Dear Jim: I would like to use some free solar heating in a south-facing kitchen. What type of simple solar heater can I build for one room? – Quinn N.
Dear Quinn: Try building a simple solar window heater for a kitchen. With a stove, dishwasher, refrigerator and other appliances that also generate heat, a solar window heater may provide enough extra heat so your kitchen actually becomes a net energy producer for your house.
A solar window heater works on the principle of hot air naturally rising. This draws room air in the solar window heater chambers to be warmed without the use of an electric fan. If you can afford a solar cell panel, a 12-volt fan could be attached to the heater.
The basic design of a solar window heater is a shallow insulated wooden box with a clear top. It is mounted in a window and tilts downward so the lower end rests on the ground. It should be about the width of the window. If you have an old glass storm door or windowpanes available for the top, make the box that width.
A longer one has more clear top area exposed to the sun so it captures more solar heat. For any do-it-yourself projects like this, it is usually best to select dimensions in multiples of 4 feet to better use standard 8-foot lumber, insulation and clear sheeting.
There is a horizontal divider inside the box to create an upper and a lower chamber. The divider is slightly shorter than the box, creating a gap at the bottom that connects the upper and lower chambers. The divider also functions as the solar collector panel.
When this box is mounted in the window, the sun shines through the clear top onto the divider/collector panel. This panel and the air in the upper chamber get hot and less dense. The solar-heated air rises and flows up the top chamber to the window and into the kitchen.
This upward airflow draws cool room air into the lower chamber at the window. This air flows down to the gap at the bottom of the divider/collector and up to the top chamber to be heated and sent back into the kitchen. Install deflector panels on the open window end to keep the already solar-heated air from being drawn back into the heater.
To improve effectiveness and heat output, line the inside of the box with rigid, foil-faced foam insulation. This reduces heat loss as the room air flows in the lower chamber. To absorb more solar heat, face the foil toward the interior and paint it flat-black.
Install tight-sealing doors on the open end in the kitchen window, because you must close off the chambers at night. If you do not, the airflow will run in reverse and actually cool your kitchen at night.
Dear Jim: Our son keeps his computer on 24/7 because he says it will make it last longer and that doing so costs only a couple cents per month. Does a computer use much electricity and is he right? – Sandi R.
Dear Sandi: The amount of electricity a computer uses depends upon its type, age and number of peripheral components. Newer ones go to sleep if left on 24/7, to draw less electricity, but they still draw some. The moving parts in a hard drive and fan will wear out sooner the longer they run. Also, the longer it is on, the greater the risk that power surges may harm it.