You Solar Heating System Answare And Reviews

Question: Saran wrap on solar heating system?

(Posted by: Dave on 2009-06-16 14:18:15)

Will putting saran warp over a solar heating system (black pipes on top of a black plywood) work to increase the temperature of the pipes? Would 1/ 8th glass sheets be different?

Posted by: Lyssy on 2009-06-16, 14:30:37

The saran wrap could possibly melt, depending on the temperature of the pipes & plywood. Also, even if it doesn't melt, the higher temperature the saran wrap reaches, the less effective it's going to be in insulating the pipes. The glass would provide better insulation.

Posted by: Breath on the wind on 2009-06-17, 22:33:40

If you had a picture it would be better to diagnose your situation. Also it might make a difference where you are located and what you are heating, hot water or house heating. I would guess you live in a relatively warm environment with little or no freezing and you are heating hot water. Yours may be a Thermo-siphoning system (doesn't use pumps) and may work quite well on some days but not enough of the days for you so you are trying to make the system more efficient. There are 3 main types of solar thermal collectors. The latest are vacuum tube collectors. These produce high temperatures and work better in cold and cloudy conditions. The next would be flat panel collectors. These typically have a collector surface located in a box with glazing over the top of the box. The last would be some sort of open loop that may be placed on a roof. This last is the simplest and the least effective. The primary issue is heat gain vs heat lost. The considerations are the way heat is transferred by convection, conduction and radiation. You want your collector to heat up and then transfer heat to the medium you are using to move the heat to a useful place. But as the system heats up it will tend to lose more heat to the surrounding environment. A box collector makes several improvements over open tubes. A flat black collector area will absorb more of the sun's radiation. If the area is conductive like copper sheets painted black it can then conduct heat to the copper pipes it is in contact with. But as the collector area becomes hotter than the surrounding environment the heat loss also increases. Glazing changes this my making a little micro environment within the box. Glazing helps to hold the heat against convective losses. Some sunlight is also bounced off of glazing. In cold environments double glazing is important because the losses are greater and the heat gain may not be as much as a warmer environment. Glazing is like insulation as it prevents heat loss. In general it is better to insulate at night than to add a second layer of glazing. This is because glazing blocks some solar radiation. The difference between different forms of plastic as glazing and glass is slight. Glass may be more conductive for heat loss but it also allows more light to enter and is opaque to infra red radiation. But glazing is only going to work if their is a relatively air tight environment. There has to be a box. Just putting glazing on top of exposed pipes is not going to be as effective.