Alternative to Rigid Foam Cover, Air Cover,S

[Johnny D]

I am looking at getting a Spacap due to the reasons a rigid foam cover is too heavy for a one person operation, limited to space, <17" on the left, none on the right and don;t want to block the view out the back.  This is the only solution I have come up with for my planned purchase f the Maxxus

OK, I am requesting feedback from people who actually have experience with these, not necessarily your guesses. I read the posts about those who test the effectivness of the insulating effeciency and here is the response from the company that makes them.  

 Heat gun
July 13th, 2007
I have seen a posting on a competitors website regarding a comparison of outside temperature of a rigid foam spa cover verses the outside surface temperature of a SpaCap. The information given there is an opinion of how well the cover works based on pointing a heat sensing gun at both covers while in use. Although the person doing the test may have performed the test accurately and may have used a very sophisticated testing device, they did not actually address the function of a spa cover, keeping the water in the spa warm while using the least amount of energy doing so. Let me start with a brief description of the difference between the two methods of covering the hot tub. First the traditional foam spa cover. A rigid foam cover lays across the surface of the spa on top of the Acrylic, like a bridge over the spa water. In most cases this rigid piece of foam is several inches off the water it is supposed to be keeping warm. Ten to twelve inches of gap between the hot tub water surface and the bottom of the spa cover is not unusual.

The SpaCap hot tub cover by comparison lays right on the waters surface and uses closed air chambers to insulate the spa water, similar to how the layers of glass on your storm windows insulate your house. The big difference to note in these two styles is the gap between the spa water and the cover being used to insulate it. The dirty little secret behind rigid foam spa covers is they can Never effectively insulate the spa water. Instead it just covers the spa, reducing, but not eliminating the steam that would otherwise rise off the water’s surface into the atmosphere. A rigid foam cover twelve inches thick would still allow the warm spa water to evaporate into steam, rise up, cool, and condense on the bottom of the cover (if you own one you have seen the droplets on the bottom). The condensation then falls back into the spa cooling the water causing the spa to work harder to keep the water warm.

Another thing that happens in rigid foam covers is saturation. You may notice this, as it takes more muscle to lift your cover off your hot tub. Because of the spa environment the steam from the spa water eventually seeps into the foam and condenses in the little air spaces inside. This begins to happen almost as soon as you put it in service. Since those little air spaces in the foam represent insulation, the little value it might have is gone rapidly long before you notice the cover gaining weight. Once the ambient air temperature gets down to freezing the moisture trapped in the foam freezes so in fact you are now trying to insulate your spa with a block of ice. If you were to point a heat sensing device at that frozen block of ice would read the same temperature as the ambient air. Does that mean it is perfect insulation? Unfortunately, no.

Herein lies the problem in the heat gun test. Since no rigid foam cover is actually in contact with the water it is supposedly keeping warm and it is in fact in contact with the ambient air above the spa, it is only natural that it would be more relative to the outside temperature. By comparison the SpaCap laying right on the water surface insulates the water in two ways. First, it severely reduces the open water surface by coming in direct contact with it. The spa water consequently cannot evaporate as it does under the foam cover. A side benefit of the reduced evaporation is that the spa chemicals will also stay more consistent and you will be able to use less to get the same results which aside from saving frustration also saves you money. The second way the SpaCap insulates is by using closed air chambers stacked one on top of the other to create barriers of air between the outside ambient air and the water in the hot tub. Think of it like layering your clothes. If you have one layer of clothing on you stay slightly warmer than you would walking around naked. Two layers of clothing on you trap another layer of air around your body and stay warmer. More layers of air equal more insulation so you put on a coat over your shirt, over your underwear. The same is true in the animal kingdom. An animal that has to keep warm traps air around its body with feathers or fur. As long as that system is in good condition the animal stays warm. If the feathers or fur looses their ability to trap air, say it gets covered in oil, then the animal quickly looses heat and dies. Why? Because saturated fur, feathers or foam does not insulate. Trapped air insulates consistently. A twelve year old SpaCap still insulates as well as the first day it was put in service as long as it is still holding air. If you were to point a heat sensing device at the outside of a SpaCap while it is in use it would read some measure of heat, higher than the ambient air. Does that mean it is not insulating? No, it simply means that it is not perfect insulation. ...Continued next post

[Johnny D]

...Continued from last post...
  A better test would be to place the heat sensor in the water since after all, this is the focus of the insulation. Reading the temperature of the water and how fast it lost heat under a rigid foam cover verses how fast it lost heat while covered with a SpaCap would be a more useful test. This test we have done a number of times over the years. The SpaCap beats every foam cover ever made in this test. There is no other rigid foam filled cover that even comes close enough to call it competition. In fact a saturated foam filled cover tests the same as a piece of wet plywood.
The SpaCap is several times better at keeping spa water warm than its nearest competitor. If energy efficiency is what you want get yours with all the insulation options and your SpaCap will pay for itself with the energy you save.

[Vinny]

Why even waste your money on the SpaCap, just buy a closed cell foam blanket to lay over the water. You could save yourself a lot of money there as well.

A typical window filled with argon gas & low E glass has a R value of 3. Windows are extremely inefficient.

Most people who look for heat retention use a heat camera and one of the problems with uninsulated walls is the convection current inside the wall. Rigid foam is not the best insulator but it does have a R value that's greater than 3. How much heat on the outside of a structure is an indicator on how well the heat is being retained. As an ouside surface gets cold, the inside surface is trying to heat it up. A warm body trys to warm up a cold body - this is a law of thermodynamics. In winter months when it's cold outside, sitting by a window makes a person cold because your body is trying to heat the window. When you look at winter clothes it is either the layering of clothes that produces cells of trapped air or a filler that does it - at 20º 2 thin layer of nylon is not much protection.

As you can probably tell, I am not a fan of the SpaCap, it seems like a good idea but it definately falls short. As far as convection currents buy a foam blanket for under the spa cover and there eliminates that problem and you still have a higher R valued cover to insulate further.

Last year I did a test on my spa to see how much heat it would loose, I have a blanket and a rigid foam cover. All I had going was the circ pump and the temps were in the 20's & 30's, in 4 1/2 days I lost 18º total if I remember correctly. My cover was a year old and not waterlogged. My cover is a little over 2 years old and still not waterlogged. At the same time another member here with his spa did the same test except he kept his filtration cycles constant and his spa kept temp - mine is a Artesian and his is a Arctic

There's some definate marketing ploys being given by SpaCap.

Good luck in you decision!

[Johnny D]

Thank you for your well worded response.  I looked up spa blanket, closed cell smooth. http://www.spadepot.com/shop/Floating-Blankets-C637.aspx Seems reasonable.  

Here is what one owner said..."Spa blankets are a pain. When I open my tub, I flip the cover back half-way, then fold the spa blanket over the half-open cover, then raise the cover to the full open position. That’s the easy part. The hard part is trying to put the spa blanket back without submerging part of it and flooding the top surface with water. It’s very hard without a second person.

Sundance makes the spa blanket situation worse in two ways. First, the tub is highly sculptured and has a special area (they call the “bucket”) for the filter. If you have had a spa you know you get to cut out the blanket to follow the contours of the spa yourself. This is much harder when there are all those curves and turns involved. The second aggravation is that during daily filter cycles, the right-rear corner jets can blast the blanket into a scrunched up wad in the middle of the tub. Leaving the diverter valve in the single jet position and using a stiff blanket with lots of overlap at the edges helps a lot. "

Another comment about foam...""Because of the spa environment the steam from the spa water eventually seeps into the foam and condenses in the little air spaces inside. This begins to happen almost as soon as you put it in service."

     Seems like this has it's limitations as well.  

[Dr. Spa™ Ret.]

Another comment about foam...""Because of the spa environment the steam from the spa water eventually seeps into the foam and condenses in the little air spaces inside. This begins to happen almost as soon as you put it in service."

This is simply not true. Well, the first part is, "eventually".... The second half, "begins to happen almost as soon", isn't.

[txwillie]

Never seen these B4. Who knows, it might work, but jeeze, can you imagine having to deal with pulling that on and off every time? What a PITA! You might wanna think about all the dirt and such that will stick to the wet inner side of this thing and get dragged into the spa every time you put it back on. I have a Maxxus and yes the cover is big and heavy, but it takes on person 15 seconds to open or close it with a lifter.
I really suggest you think this one through a bit more.

txwillie

[hottubdan]

Johnny,

It appears no one here has experience with the Spacap.  You may be our reporter.

My feeling is that if Hot Spring (for whom energy efficiency is a key engineering feature), Sundance, Marquis, D1 and all other manufacturers do not offer it as an alternative, there must be a good reason for it.

Spacaps claim that dealers don't offer it because they want to sell a product that needs periodic replacing is unprovable and would not apply to spa manufacturers. Most do not make covers and are looking for satisfied spa owners for referals and repeat spa business.

[Johnny D]

Never seen these B4. Who knows, it might work, but jeeze, can you imagine having to deal with pulling that on and off every time? What a PITA! You might wanna think about all the dirt and such that will stick to the wet inner side of this thing and get dragged into the spa every time you put it back on. I have a Maxxus and yes the cover is big and heavy, but it takes on person 15 seconds to open or close it with a lifter.
I really suggest you think this one through a bit more.

txwillie

Good points.  I just don't have the room on either side of the spa to have a rigid foam cover with a lifter.  The max clearance between the tub and the wall will be is 17" on one side.  Because the Maxxus has a convex back and concave front, I've been told you can't mount a lifter to it. The backside will obscure the view.  

As far as dirt being dragged in, I'm planning to have decking about 2' off the ground on the side that has 17" and hoping it will slide into that space.  

[Dr. Spa™ Ret.]

Only need about 6" of clearance.

[Johnny D]

Only need about 6" of clearance.

True BUT, you can't mount the lifter on a concave or convex surface which the front and back of the maxxus has both.  

[txwillie]

I really think you need to look at your space and the tub. The cover on the Maxxus is hinged/opens to the back (the side opposite the control panel and equipment access). The Maxxus cover is 3-piece due to it's size. The lifter attaches to the sides, which are flat. As for dirt, there is always dirt, grass, leaves, and such on any surface outdoors, no matter how often you sweep it/blow it off. That stuff will stick to anything you put on it, especially if it is wet and then get dragged into the tub. The tub seems to magnify stuff, so even a little grit stands right out.

txwillie

[Chris_H]

You can use a Covermate III for the Maxxus.  They make one specifically for the Maxxus.

Edited to add:
Nevermind.  I did not understand what you wanted to do.  You want the cover to go to one of the sides not to the back.  

Have you considered getting a 4 piece cover?

[Dr. Spa™ Ret.]

A custom 2 piece, fold in half cover can be made, to be opened to the side.

The cover lifter CAN be made to work simply by a wooden shim, shaped to the curvature of the spa, to fit under the mounting bracket. Longer bolts may be necessary to go through the bracket, shim and into the spa framing.

[txwillie]

Nevermind.  I did not understand what you wanted to do.  You want the cover to go to one of the sides not to the back.  

Why not just choose a square spa like the Optima?

[txwillie]

Hmmmm... This thing got me curious. I did a G**gle on Spacap and came up with a review site for them. Not much positive to say on there. In a nutshell, energy use/electric bills seem to be higher, dirt & such seems to be able to get blown in, and (something I didn't think of) what happens to them when they are not strapped down and the wind blows, ie: when you are in the spa, or pulling it on or off? I'll let ya'll figure that one out. Then there is the whole Boyles Law thing....

As someone said, if they worked, everyone would be doing it.

txwillie