February 7,1998

Insulation, Heat Retention, and Freeze Damage


I often get letters and questions from people about this subject. One of the most important question for most people is; "How much is it going to cost me?".

There are two answers to that question. One is the selling price of the spa, and the other is the cost to operate and repair the spa over time. You can save as much as $2500 or more over a period of ten years by buying a spa that costs $500 to $1000 more than other brands, simply because it is made better. However, not all higher priced spas are better. Price is not the only determining factor is spa choice. How the spa is made is!!

I have found that people really want a spa that doesn't cause problems. When our service customers have a spa that is less than 5 years old, and the repair bill is over $1000,00, I feel bad for them. The spa company that built that piece of trash IS THE PROBLEM!. It is a real dilemma for me, because now our company is involved. I usually recommend they get rid of the spa, and buy one of ours. If that isn't possible, then we will fix it. The three common repair problems are (1) leaking full foam spas, (2) burned out poorly designed equipment and (3) cracks and blisters on the surface of the spa shell or discoloration on the spa shell. Sometimes a spa will have all three problems.

There is one other really bad problem, freeze damage. If severe, it is the worst problem a spa owner can have.

There is a difference between a "manufacturing defect" and defective manufacturing! If a manufacturer is using good sound engineering and manufacturing methods and an individual spa has a warranty problem, that is one thing. If the manufacturing methods are developed only to insure a high profit, and the manufacturer knows that the spa will not last for more than the length of the warranty without major problems, that is something altogether different!

Some spa builders have determined that by filling the spa cabinet full of foam, they can make a really cheap shell and support it by foam. The sales people will tell you it is for heat retention, but that is not the reason for all that foam. It simply saves manufacturing costs. One person with a spray gun and about a half an hour, and the spa support is built.

Isn't it ironic that two of the most popular spas made today are also using the cheapest manufacturing methods available! But the real irony is, they sell them at premium prices. Some of the most expensive spas available today use the cheapest shell manufacturing methods possible!

To a lay person, it sounds reasonable when salespeople say that a spa cabinet which is full of foam "gives the best thermal insulation", but that is far from the truth.

Independant tests from Colorado State and Arizona State Universities, and my own test have shown that to be false. The best insulation is done in layers and is called thermal pane or thermo-loc. In thermal pane insulation most of the electrical energy is conserved.

There is one "catch" to thermal pane insulation. The spa shell has to be made strong and self supporting. It costs more to make a strong shell!
CLICK HERE See our shell cutaway page

I always ask people this question when the subject of insulations comes up: "When two inches to four inches is the thickness of the stoutest foam spa cover, where the heat loss is the greatest (heat rises),why do we need so much foam on the bottom and sides where the heat loss is so small?"

If a person holds a styrofoam cup in one hand and pours some boiling hot coffee in it, then places a finger in the coffee, in less than a minute, second degree burns occur. (A million dollar law suit happened this way!)

When less than 1/16 inch of foam can keep the cup so cool on the outside, how is it that you need 10 to 34 inches of foam in your hot tub???

Almost all of the insulation value in a full foam spa is wasted. It is used as a low cost way to support the spa and that is all.

Freeze damage is much more likely to occur in a full foam spa. If the entire cabinet is full of foam, the equipment compartment has to be vented to the outside air. (The compartment is too small for warm the air to circulate and be transferred into the spa water, so heat is lost.) When the equipment stops for any reason, the cold air in winter enters the compartment and freezes the water inside the equipment and exposed pipes. One of the most assured laws of chemistry is that water expands when it freezes. As it expands, it breaks things, namely, full foam spas' pump housings, heater housings, and any exposed pipes. If you think that full foam spa was a deal, just wait until you have to replace those items. Freeze damage is not covered by any warranty!

One of my favorite things to do is to ask full foam spa sales people this question: "What will happen if the spa is left unattended for two days at zero degrees, while the electric power is off?"

I have gotten some rather unusual responses, red faces, and just plain BS. One spa salesman told me that they "have self sacrificing parts that break to save the rest of the spa". I thought to myself: How noble of those parts, the heater manifold, the pump housing, and the other most expensive parts in the spa.