Confessions of a ThermoSpas Employee

Everything You Always Wanted to Know About Hot Tub Covers — Part I

At ThermoSpas we are frequently asked about hot tub covers: what they’re for, how to choose one, and how to care for them. Hopefully we can address some of these questions today to help you make the most of your leisure time by taking the worry out of your cover choices!

What is an ASTM Cover?

ASTM stands for American Society of Testing Materials, and they have developed a standard for testing hot tub covers (ASTM F 1346-91). An ASTM cover is tested to hold up to 275 lbs. in weight and is primarily intended to protect children five years of age and under, and pets; however, adult supervision is the only real way to prevent accidents. The benefits of an ASTM cover are safety, better heat retention (which leads to cost savings) and longer life.

What do I look for in a foam core?

The foam used in our covers meets the strictest Air Quality Standards and can be recycled. Given the critical environmental issues we now face, ThermoSpas feels strongly that we should do everything we can to minimize waste and pollution. The foam cores provide rigidity, strength, and insulation for the hot tub cover. The taper of the foam from 3.5 inches at the center of the cover to 2.5 inches at the edges of the cover allows the rain to run off quickly. Most hot tub covers use a 1lb. density foam, which has a one year warranty, is lighter in weight, and has less of an insulating value. ThermoSpas hot tub covers use 1.5 pound density foam with a 3 year warranty. The foam doubles the efficiency of the cover in retaining heat. With a ThermoSpas hot tub cover, a hot tub with the heater turned off and an outside temperature of 32 degrees will lose less than 9 degrees in thirty hours.

Why is my cover so heavy?

Water absorption by foam cores is the result of holes in the plastic surrounding the foam. The foam acts like a sponge, absorbing water vapors and making the cover very heavy. ThermoSpas new hot tub covers are manufactured with a superior heat sealing system that increases the resistance to water vapor absorption four times better than covers manufactured by competitors. This seal improves the life of the hot tub cover and provides the best protection against water absorption.

What makes one vinyl better than the other?

The vinyl covering of a hot tub cover is commonly called the “skin,” and is sewn together to encase the foam core. It protects the foam core and supports the handles, tie down straps and hardware. The stitching is very important to the life of a cover. Lesser grade vinyl only allows for single stitching (common on most hot tub covers). ThermoSpas covers are now manufactured with a high grade marine vinyl, which not only allows for double stitching, but contains mildew and ultraviolet (UV) inhibitors which prevent the color from fading. The actual stitching now used on ThermoSpas ASTM covers is extremely strong. We use a “carriage” stitch that, even when cut, will not come undone for more than a couple of stitch lengths.  In fact, it won’t come undone unless it is put under extreme pressure!

So bottom line, because the cover should always be on when the hot tub is not in use, the vinyl cover is very critical to the appearance of the hot tub.

Stay Tuned, we’ll be posting more great tips and answers to your questions in Part II of Everything You Always Wanted to Know About Hot Tub Covers soon!