Full foam vs thermolock and a guide to helping you decide.
Are you shopping for a hot tub? Does one salesperson make a very compelling argument one way and the other salesperson make an equally compelling argument? Hot tubs are fun so try and keep your shopping experience fun too. To me this topic is the most fought over so I am hoping this saves confusion. We can do this honestly because Everything Hot Tubz sells both full and thermolocking spas and let our customers make the decision that best fits them.
Foam pros: As long as the entire cabinet is full and not a cheap partial fill it should be energy efficient. To ensure this is the case; ask to look inside cabinet of tub you are considering buying, not just equipment side but the insulated side as well. Don’t let them only show you their highest end hot tub unless that’s what you’re buying. The tub should be energy efficient.
Companies that are insulating completely should maintain very close efficiency so if you are looking at a Marquis, Sundance, Cal Spa, Jacuzzi, Hot Spring, BullFrog, Caldera or maybe couple other brands I’m missing should be within dollars of each other.
The foam supports the plumbing, this is important against SOME thermo-locking brands (I’ll specify later). This will help reduce chances of future leaks.
Companies that do offer a full-foam insulation generally do care about quality and are not normally spas that are made only to hit price points. You should be able to keep these spas and be happy with them for years.
Foam cons: If/when the tub leaks it can be very expensive to fix. Also the leaking will really hurt the insulation value of the tub as it moistens the insulation, and unless you pull all the insulation and respray (very expensive and not a wise investment for monthly savings) your tub will no longer be affordable. Also leaks can go unnoticed and keep insulation wet which can deteriorate the wood framing. These tubs can be slightly noisier. Pumps are pushed against the front panel especially as they age, which makes them noisier still. I recommend if you go with a full foam spa ensure it has a solid plastic PAN bottom. This will ensure moisture doesn’t soak into insulation from bottom. (ie:Jacuzzi 300/400 series, Marquis (not their cheap stuff), BullFrog, and a few others.) Hot Springs does not offer a PAN bottom but they seal the bottom fairly well, Sundance uses a stapled sheet that is less effective and the lower end of Jacuzzi, Marquis and all Cal Spas seem to have the most troubles with this.
Thermolock: This is a little trickier then foam fill because thermolock insulation is not created equally. Honestly I only like 2 different brands of thermolock insulators: Maax and Arctic. Both use 4″ insulation and maintain high-energy efficiency. It’s not a coincidence that Arctic is made in Canada and Maax is a Canadian company only made in the USA. Companies that offer thermolock to a lesser-stand point (IMO) are Clearwater, Master Spa, and Premium Leisure (if upgraded). These companies use thinner wall insulation and would have a harder time in colder climates than foam fill or the two above mentioned thermolock spas. Regardless, be careful about the brand, if a company is showing you an inch of insulation or less that WILL NOT BE EFFICIENT. Most online sellers use these forms of insulation, I would strongly advise staying clear of online vendors, they have no motivation to add additional quality to the spa. Thermolock pros: The pros of thermolock are they can be as efficient as foam, in some cases even more efficient. They are roughly a million times easier to repair, and because of this you see their owners keeping the spa longer and find less of them on Craigslist. As far as supporting the plumbing, that was an issue and is an issue with some brands, Maax plumbs all their manifolds and plumbing to the floor, this eliminates pulling and reduces chances of leaking. If it does leak it won’t hurt anything, which is nice. Arctic uses a unique way of plumbing which keeps glue-joints on the inside, they also make the plumbing bigger, and they have larger surface area of glue, which not seeing many leaks on their product it appears to work well!
This article was written by Ed Konarske of Everything Hot Tubz, these are all things I’ve seen and observed during my 14 years in the industry. Having been a service professional, worked with manufacturers, and now running a large service and refurbished hot tub company I really don’t have a single horse in any race. Good luck, happy hunting and if you have questions toss me an email! Even if your 1000 miles away I really enjoy helping people and answering questions…you’ll be in hot water in no time!