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What type of insulation is best for hot tubs in 2023?

How well a hot tub has been insulated is one of the biggest factors in how much it costs to run and here at Wyre Forest Spas its always topic of conversation with our customers.

You’ll certainly pay a bit more upfront for a well-insulated hot tub, but the boost in energy efficiency is bound to bring the lifetime cost down once you take running costs into account.

So, if insulation is so important, then what’s the best insulation for hot tubs?

Here’s absolutely everything hot tub owners need to know to pick a hot tub that won’t give them a shock whenever they look at their smart meter.

Not all hot tub insulation is created equal. Here’s a rundown of each type of insulation you’ll find on the hot tubs on the market – as well as our advice on which is the best hot tub insulation.

No insulation

Some hot tubs don’t come with any insulation at all.

All inflatable hot tubs fall into this camp. As a result, they cost a lot to run and might need to be brought up to temperature before you can use them (especially in colder months).

One of the reasons we recommend that you never buy a hot tub sight unseen from an online store is that some permanent hot tubs made abroad come with no insulation at all between the shell and exterior.

A trick these unscrupulous hot tub manufacturers will often use is calling a hot tub “insulated” because it comes with a cover filled with a thin layer of insulation. While these spas are technically insulated, they’re not really going to retain any heat at all.

These hot tubs cost arm and a leg to run and take an age to heat up. Plus, the components will have to work harder to maintain the same temperature, shortening their life span.

Plus, you can bet your bottom dollar that any hot tub brands willing to sell spas without any insulation will be cutting plenty of other corners, too.

Be sure to follow the tips in our hot tub guying guide to make sure you never buy a hot tub that isn’t insulated, as it will cost you a pretty penny in electricity bills to run.

Thermal wrap

Some hot tubs at the bottom end of market will be insulated by nothing more than a thermal blanket – reflective material that’s wrapped around the shell to reflect some heat back into the tub.

This kind of insulation is only slightly more effective than having no insulation at all and really isn’t suitable for hot tubs. It’s certainly no replacement for foam insulation, as it provides a fraction of the heat retention.

However, it’s worth noting that thermal wraps are fine for the swim chamber of swim spas, which don’t need to reach as high temperatures as a hot tub. So, this kind of insulation isn’t as big of a red flag if you’re shopping for a swim spa as it is for a hot tub.

Partial foam insulation

Most hot tubs are partially insulated by a layer of foam insulation that’s sprayed to their shell. This helps a hot tub retain heat, but also provides it with structural support that prevents its shell from cracking and warping over time.

We’d recommend that you discount any hot tub from your search unless it’s at least been partially filled with spray foam insulation.

However, it’s worth noting that partially-insulated hot tubs are really better suited to warmer climates than here in the UK. So, while they’re certainly a step up from a thermal wrap, you’ll make significant savings on your annual hot tub running costs by opting for a fully-foamed model.

Full foam insulation

Fully foamed spas have the entire cavity between the outside of the shell and the inside of the spa cabinet filled with foam.

The Plus:

This not only insulates the water within the shell of the spa but also the plumbing and pipe-work of the spa or swim spa. This dramatically cuts heat loss and therefore fully foam spas and swim spas are usually some of the most efficient spas to run.

The Minus: