Full foam or not full foam; that is the question.
Insulation is one of the most important aspects of the manufacturing of spas and swim spas as it is the main factor in determining the heating cost of spas and swim spas. In colder climates, spas and swim spas lose heat from their water, requiring the heater to turn on to hold the spa at the preset temperature. The poorer the insulation, the quicker spas cool, the longer the heater stays on and the higher the power bill.
There are three main ways spas and swim spas are insulated and each method has positives and negatives:
Foam on shell
Under this method, the spa's shell is sprayed with foam, usually to a thickness of around 25mm or 1 inch.
This method has two advantages. Firstly, it's cheap. Therefore, it is usually found on entry-level spas and swim spas. Secondly, if the spa leaks, it's easy to see the leak and repair it as the spa's plumbing is not usually covered in foam.
The downside, of course, is that because the spa's plumbing runs outside of the insulation, it is exposed to the cold air and this cools spas very quickly.
For this reason, foam on shell insulation generally gives the lowest level of insulation and therefore these spas and swim spas cost the most to run.
Fully foamed spas have the entire cavity between the outside of the shell and the inside of the spa cabinet filled with foam.
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.
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.
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.
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.
With this knowledge you can better understand the options available to you when speaking to a salesperson. and if in doubt make sure the company you are purchasing from backs up their claims with a 60-day money back guarantee.
Make sure to read more from our spa buyers guide section.
Author: Andrew Pullen
Andrew Pullen is the CEO of Vortex Leisure, which owns Spa World - Australia's largest retailer of spas and swim spas. Spa World features more than 50 spa and swim spa models. Andrew has been in the spa and swim spa business for nearly two decades and has an in-depth knowledge of the international spa and swim spa business.