A heavy, waterlogged hot tub cover is one of the most common and frustrating ownership problems. Traditional foam covers absorb moisture over time, become difficult to lift, lose insulating performance, and often need replacement every few years.
AIRCAP 1™ by thrml. takes a very different approach. Rather than using a foam core, AIRCAP uses an inflatable, drop-stitch construction intended to create a rigid but lightweight replacement hot tub cover. Its goal is straightforward: eliminate foam saturation, simplify replacement-cover shopping, and give hot tub owners a longer-lasting option that is easier to manage day after day.
What is the AIRCAP 1?
The AIRCAP 1 is a semi-custom, inflatable replacement cover for portable hot tubs. It uses the company’s patent-pending AirLoc™ drop-stitch technology, the same general construction concept used in high-quality inflatable paddle boards. Thousands of internal threads connect the material layers and once inflated, the cover becomes firm and structured rather than soft like a typical inflatable product.
The company’s core claim is that this design provides a strong, durable, water-resistant alternative to conventional foam-core spa covers. Because there is no foam core to absorb water, AIRCAP is designed to stay much lighter over its usable life.
AIRCAP 1 sizes and fit
One of AIRCAP’s biggest selling points is that it avoids a traditional custom-cover ordering process. Instead of measuring every contour and waiting weeks for a custom-built foam cover, customers select one of six available AIRCAP sizes, then use the included skirt system to refine the fit around the spa cabinet.
Thrml. says its four cover sizes are designed to fit over 90% of hot tubs on the market. The cover comes with three skirt lengths, allowing the buyer to select the skirt that best matches the drop from the cover edge to the spa cabinet.
The company’s SureFit™ / Spa Fitter™ process lets buyers choose a size using either:
- The length and width of the spa.
- The measurements of an existing properly fitting cover.
- The hot tub’s make and model, when supported by the Spa Fitter tool.
The corners use a standard 6-inch radius configuration, intended to work across many popular spa brands and models.
AIRCAP 1 price
AIRCAP 1 pricing is typically in the $1,000–$1,245 range, depending on retailer, configuration, and location. Hot Tub Insider reports a consumer pricing range of approximately $1,000 to $1,195, while one retailer lists AIRCAP at $1,245.
That puts AIRCAP well above a standard foam replacement cover. Basic foam spa covers commonly start around $400–$500+ upgrades, though heavier-duty foam covers and custom shapes can cost more.
| Cover type | Typical price | Primary tradeoff |
|---|---|---|
| Basic foam replacement cover | $400–$500+Upgrades | Lower initial cost; can absorb water and become heavier |
| Premium/custom foam cover | Often higher, varies by size and options | Better fit and insulation options; still foam-core |
| AIRCAP 1™ | About $1,000–$1,245 | Higher initial investment; intended to avoid foam saturation and frequent replacement |
The question is not whether AIRCAP is the least expensive cover upfront—it isn’t. The real value proposition is whether a buyer prefers a lighter, potentially longer-lasting cover over paying less initially for a traditional foam design.
Installation and included components
AIRCAP is designed to be a quicker alternative to ordering and installing a custom foam cover. The cover ships to the customer, and the installation process is described as:
- Inflate the two cover halves with the included dual-action pump.
- Select the appropriate skirt length.
- Attach the skirt using the ZipTech™ waterproof zipper system.
- Secure the cover with the included locking tie-down straps.
Thrml. says this can be done in 10–15 minutes. The company also describes the skirt as replaceable, which could be useful for cosmetic wear, UV exposure, or pet damage without replacing the entire cover.thrmltech+1
The standard package reportedly includes:
- AIRCAP 1 cover halves.
- Dual-action pump.
- Three skirt lengths.
- Four keyed locking tie-down straps.
- Repair kit.
Key Features Worth Noting:
No foam to absorb water
Foam saturation is the Achilles’ heel of many conventional spa covers. Once moisture gets into the foam core, the cover becomes much heavier and its insulation performance can decline. AIRCAP’s welded, polyurethane-coated drop-stitch fabric is intended to be waterproof and avoid that water-absorption cycle
Lightweight handling
A traditional cover can become difficult to open after years of water absorption. AIRCAP is designed to remain lightweight because it does not contain a foam core. That may be especially appealing for older owners, solo users, or anyone tired of wrestling a heavy cover several times a week.thrmltech+1
Semi-custom sizing
Instead of an 8–10 week custom-cover order, AIRCAP uses six core sizes and a modular skirt system. That can make replacement faster and easier for many standard square and rectangular spas.thrmltech+1
Replaceable skirt system
The patent-pending ZipTech™ skirt system is more than a fit feature. Because the skirt is separate from the main cover body, it can be replaced if it gets torn, chewed, faded, or otherwise damaged.
Safety certification claim
A retailer product listing states that AIRCAP 1 is designed to comply with ASTM F1346-23, the ASTM performance standard for safety covers and labeling requirements for pools, spas, and hot tubs. Buyers should still follow all manufacturer installation instructions, use the locking straps as intended, and confirm current certification documentation with the retailer or manufacturer before purchase.
Is AIRCAP 1 worth the money?
AIRCAP 1 makes the most sense for hot tub owners who are replacing a heavy, failing foam cover and want to spend more upfront for convenience, water resistance, and a modern design.
It could be a particularly strong fit if:
- Your existing foam cover is waterlogged or difficult to lift.
- You want a lightweight replacement that will not gain weight from water absorption.
- You do not want to wait for a made-to-order foam cover.
- Your spa fits one of AIRCAP’s six standard size categories.
- You value a replaceable skirt and a modular design.
- You plan to keep your hot tub long enough to justify a premium replacement cover.
A conventional foam cover may still be the better option for someone prioritizing the lowest upfront price, needing an unusual shape or exact custom radius, or wanting a specific foam-density and taper configuration for extreme climate conditions.
The AIRCAP 1 is one of the more interesting innovations in the replacement hot tub cover category. It is not trying to be a cheaper foam cover but rather it is trying to solve the traditional foam cover’s most frustrating issues: water absorption, added weight, and recurring replacement. Not to mention it’s more environmentally friendly.
At roughly $1,000 to $1,245, it is clearly a premium purchase. But for the buyer who wants a lightweight, semi-custom, water-resistant replacement cover that can be installed in minutes, AIRCAP 1 offers a compelling alternative to the standard foam-core approach. Its four-size fit system, included adjustable skirts, drop-stitch construction, and three-year manufacturing-defect warranty make it worth considering before ordering another traditional cover
Hot Tub Insider receives regular promo codes and discounts from Thrml Covers. Please complete our contact form to inquire about current promo codes or specials.
For more information on how to shop and compare hot tubs before purchasing please visit our hot tub buyer’s guide pages. You can also click on the pink boxes at the top right of every page to get a free local quotes from dealers in your area. Or, click our “Spa Buyer’s Consult” link above to get one-on-one expert advice on how to shop around for the best hot tubs available in your area.
