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:
Fully foamed spas are extremely difficult and expensive to service. Firstly, spas and swim spas can develop leaks. If the spa does develop a leak, it is often not noticed for months or even years because the foam can soak up and hold a large volume of water, nearly equal to the volume of the spa.
This large amount of water not only transfers the heat away from the spa much more rapidly but also weighs a large amount. This can have a catastrophic impact on spas installed on elevated decks and has been known to cause structural damage to decking. The source of leaks is very difficult to find because of the waterlogged foam.
When a leak is diagnosed, the foam needs to be chiselled away from a wide area before any repairs can be made. The foam needs to then be reapplied which is very costly.
It is worth noting that several brands of spas must use full-foam insulation as it also forms part of the structural support of the shell. Most reduce the costs of repairs and the lifetime cost of owning a spa.
Perimeter or cabinet insulation
This system is becoming very popular due to a number of advantages it has, with very few disadvantages.
The Plus Points:
Firstly, it's relatively low cost of manufacture means that mid-market brands can use this method. Because the insulation is on the inside of the cabinet, like full foam, both the water within the shell and also within the plumbing is insulated. Unlike full foam, if the spa requires repair, the insulation is removed when the cabinet is removed giving unobstructed access to plumbing and equipment. This significantly reduces the costs of repairs and the lifetime cost of owning a spa. One of the biggest benefits, however, is that the perimeter insulation is able to capture the waste heat from the pumps as they run and recycle it to assist in keeping the spa's water hot. It also helps to insulate against noise loss from the pumps making spas fitted with perimeter insulation very quiet.
The Minus Points:
Whilst most perimeter insulation will not quite meet the insulating performance of full foam, some manufacturers offer a very high-performance perimeter insulation option suitable for extremely cold climates such as Canada and Scandinavia. For other milder climates such as Australia and most parts of New Zealand, regular perimeter insulation is recommended as the pay off of full foam insulation is negated.
In summary
With this knowledge you can better understand the options available to you when speaking to a salesperson and, if in doubt, give Wyre Forest Spas a call today.
All the best with your research!