What you should look for when buying a replacement cover

The most important aspect to consider when looking for a spa cover replacement can be summed up in one syllable: foam. And this important feature can be analyzed using the following three criteria:

•    density  •    thickness•    taper Density

One to consider about the foam in your new spa cover is the density, which is calculated in pounds per square inch.  A typical foam density is 1 lb., with 1.5 lb. and 2lb as other options. There is one basic equation that explains foam density: the closer the cells of the foam, the higher the foam poundage and the more money you will spend. These extra dollars, however, invest in better performance of the three vital aspects to the operation of you spa cover: higher weight capacity, saturation points, and R-value, or the insulation value rating of a product .  Higher foam density means the cover can resist more weight.  Obviously the higher foam poundage is the best choice since in the long run your operations costs will be lower, and as far as saturation point is concerned, it will take longer for the cover to become waterlogged if for some reason the vapor barrier, the plastic wrap around the foam, gets punctured.  If you live in in a place with perpetual summer, then a 1 lb. density should do the trick, but if you live with lots of snow, the 1.5 lb. would add extra coverage for those days with two feet of snow piling up on your spa cover. Thickness

Another aspect closely linked to density to consider about the foam in your new spa cover is the thickness. In the Medieval days, hot tub covers were a couple inches thick and horizontal and level—no nonsense.  Lots of snow and rain, however, wreaked havoc on a simple system like this, causing the center to sag and the foam to soak up water, making it heavy and hard to move.   As with density, the thickness of the foam should reflect the conditions of your spa. A higher foam thickness will provide not only better insulation for extreme temperature shifts but will have a stronger load capacity, the most important aspect of foam thickness. The simple equation for thickness is that the cover can hold more weight as the thickness increases, but the cover also weighs more.  A tapered cover with a thickness of 6" to 4" can hold roughly 250 pounds—which is a good choice if you envision people walking on the cover, one tapered with a thickness of 5" to 3" half that weight—the most traditional all-season cover with a solid mix of load capacity and portability, and one tapered from 4" to 2" only about 50 pounds—which is usually sufficient for indoor tubs. Taper

One other aspect that goes hand in hand with density and thickness to consider about the foam in your new spa cover is the taper, which acts like a peaked roof to let snow and rain drain off the cover instead of collecting in puddles and causing mold. The highest part is the foam in the middle of the tub which then tapers down to the outside edge, acting as a run-off.  Just as with density and thickness, you should consider the needs of your spa when deciding on the taper.  Outdoor hot tubs in cold and rainy climates need thicker tapers while indoor tubs do not.  For this situation you may consider a heavy-duty taper like 6" to 4" or a 5" to 3".  A more typical taper, and less expensive, would either be a 4" to 2" or a 3" to 2" which would be sufficient for most hot tubs.

Source : articlesbase.com