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that all spas are comparatively efficient with the cover on
Mom always said, "wear a hat, you lose most of your body heat through your head."
There is an assumption in that old saying that you've already bundled up with an approprite coat and merely need to be reminded about the head!! Mom would have had a fit if you didn't have a heavy coat on as well.
Awfully extreme wording, to me. All??? Some, most, many, may have been better qualifying words to use.But what do I know? Just an observation on the statement!!!
No Steve I do not buy that statement.IMHO,While a good insulating cover is important, the vessel (The Hot Tub) itself acts like a huge heat sink, pulling heat right through it. Fiberglass and acrylic are very poor insulators of heat. If you have ever owned an uninsulated fiberglass truck canopy you will find that it sweats because fiberglass is a very poor insulator. The same thing happens with boats. That is why the inside walls of a fiberglass boats are insulated with a very fiborous carpet to insulate it and increase its evaporative qualities to prohibit sweating caused by the conductive qualities of fiberglas transfering the cold temperature of the outside water.So the more foam insulation on the underside of a spa the better to stop this transfer of heat loss and the more efficiently the tub operates.In very cold climates, like the northern part of the US and all of Canada this is a very important factor to consider.Of course because of the evaporative properties of hot water, the surface presents the greatest heat loss of all, so a good quality thermal cover and an insulating blanket are your best defense from loosing surface heat energy.Beyond the heater, there is only one other factor in operating costs and that is the size and number of electric pumps. The fewer pumps the less it costs to operate.Regards, Zz