From the HS website:
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"W INTERIZING YOUR SPA
Your Hot Spring spa has been designed for year-round use in any climate. Here are some steps you may want to take this time of year to ensure maximum energy efficiency.
If you live in an area which has freezing temperatures, you should purchase a Winter Blanket which is available at your local Hot Spring spa dealer. This vinyl-covered, fiberglass insulated blanket, which installs inside the equipment compartment door, provides an additional precaution against partial freezing of some of the components and maximizes the spa's energy efficiency"
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http://www.hotspring.com/Hot_Tub_Customers/spa_care.htmlShould this not apply then to Caldera and Hot Spot spas?
Also, HS dealers: are there warranty issues with a DYI approach, or does one have to buy the insulation from a HS dealer?