Spacap (foam Spa Cover Alternative.) Long

[Johnny D]

I am looking at getting a Spacap (air bladder filled flexible cover) 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 of 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. I am in SoCal so we don't have temperature extremes anyway but this subject may come up.

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. 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.

Your comments appreciated!

[Dr. Spa]

First of all, once the humidity of the small amount of air beneath a conventional cover reaches a humidity level of 100% ZERO additional evaporation takes place. The time to reach a 100% humidity level is, oh, about 5 seconds.

"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."

Eventually? As soon as put into service? Which is it? A contradiction so soon sounds like..... well, "someone" else we know. Eventually is the correct answer. Eventually the protective poly wrap around the foam breaks down and allows moisture to penetrate into the foam. How long this takes depends on a lot of things, from the quality of the cover, to your use of chemicals. My own cover is over 6 years old and weighs the same as it did when it was new (yes, I DO periodically weight it).

I seem to keep rather warm in my home during the winter, even though the air in my house is also heated. By the way, most energy companies evaluate the heat efficiency of a home by pointing a thermal camera at it.

The purpose and intention of insulation is to prevent heat from escaping into the atmosphere. Heat that escapes into the atmosphere is what is lost/wasted energy. A thermal camera will show beyond a doubt that amount of heat that's escaping into the atmosphere.

Air as an insulator........... Yes it woks well in animals fur, it doesn't work all that great in storm windows. The reason is what's called convection. An air space over 1/4" is diameter no longer efficiently insulates, instead it takes on currents (movement) that moves the heat form one side to another rather quickly. Glass have an R value of about R-1. Double glazed windows, about R-3. A fully insulated wall, over R-15.

Again, a better insulator prevents more heat from escaping into the atmosphere.

A comment form someone that actually owns one;

From D.S

AFTER 6 MONTHS OF TEMP. TESTING 2 TIMES A DAY WHEN THE AM TEMP IS in the 40s I will lose 5 degrees in 5 hours . Thats extreme. The cap with 3 bladders is a pain get on and off.

[Johnny D]

First of all, once the humidity of the small amount of air beneath a conventional cover reaches a humidity level of 100% ZERO additional evaporation takes place. The time to reach a 100% humidity level is, oh, about 5 seconds.

"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."

Eventually? As soon as put into service? Which is it? A contradiction so soon sounds like..... well, "someone" else we know. Eventually is the correct answer. Eventually the protective poly wrap around the foam breaks down and allows moisture to penetrate into the foam. How long this takes depends on a lot of things, from the quality of the cover, to your use of chemicals. My own cover is over 6 years old and weighs the same as it did when it was new (yes, I DO periodically weight it).

I seem to keep rather warm in my home during the winter, even though the air in my house is also heated. By the way, most energy companies evaluate the heat efficiency of a home by pointing a thermal camera at it.

The purpose and intention of insulation is to prevent heat from escaping into the atmosphere. Heat that escapes into the atmosphere is what is lost/wasted energy. A thermal camera will show beyond a doubt that amount of heat that's escaping into the atmosphere.

Air as an insulator........... Yes it woks well in animals fur, it doesn't work all that great in storm windows. The reason is what's called convection. An air space over 1/4" is diameter no longer efficiently insulates, instead it takes on currents (movement) that moves the heat form one side to another rather quickly. Glass have an R value of about R-1. Double glazed windows, about R-3. A fully insulated wall, over R-15.

Again, a better insulator prevents more heat from escaping into the atmosphere.

A comment form someone that actually owns one;

From D.S

AFTER 6 MONTHS OF TEMP. TESTING 2 TIMES A DAY WHEN THE AM TEMP IS in the 40s I will lose 5 degrees in 5 hours . Thats extreme. The cap with 3 bladders is a pain get on and off.

Thanks for taking the time on your well thought out response. Not sure what to do since a regular cover does not seem to work due to space limitations. I did not realize that your last comment, "The cap with 3 bladders is a pain get on and off." was true. The videos I saw made it look easy including this one where the guy has a broken arm.

[104 Degrees]

The videos I saw made it look easy including this one where the guy has a broken arm.

Why didnt they show the one armed person putting it back on?? it looks like it would lose some steam in a good wind"the corners". It also looks like its going to work better in a warmer climate then in a colder one.

Good luck John 104 degrees

[Dr. Spa]

The only part shown putting it back on was with 2 people. How is it with 1 person?

And what about safety??? The ASTM standards for a spa cover are intended to prevent a child under the age of 5 from gaining access to the spa with the cover on. One of the tests is to see if a 5" diameter ball (representing a childs head) can pass under the cover with the cover attached to the spa.

[mxypltrk]

Spa covers of thick rigid foam gradually get waterlogged and cave in, like mine did. So when I saw an ad for an innovative design at SpaCap.com, I got interested. The Spa Cap is essentially a large air bladder enclosed in a couple of layers of heavy-duty marine vinyl, so it sounds like a promising product.

It is not. Its insulation qualities are close to nil, and worse, the company's got the worst customer service this side of Attila the Hun.

I bought a Spa Cap, and after watching the company's online instructional video, I installed the cover appropriately. From that day, our electric bill skyrocketed. During the previous year, when we used a foam cover, our electric bill averaged $100 per month. With the SpaCap in place, our first month bill was $177, the second was $362, and the third, $571!

Of course, I turned off the tub and phoned SpaCap. I left several messages and then e-mails, and never got a response. I finally reached a woman in SpaCap's office, having possibly caught her off guard. She listened to me and asked me to send them a photo of the installation. I did that the same day, waited a week, and then began calling and e-mailing once again. Finally I reached the same woman. She told me the company's president had concluded I hadn't tacked the cover down with enough fasteners, and he'd already shipped me more fasteners. I'm glad I didn't wait by my mailbox.

I returned the cover to SpaCap, enclosing a request for a refund under the warranty, which covers workmanship and materials for three years. Since it didn't insulate worth a fig, it wasn't a genuine spa cover, so was completely defective. As you might guess, I heard nothing further from them.

If you go to SpaCap's website, a subpage, "R-Factor Testing Results," offers data on the product's insulation capability. The study, done by Dr. H.F.Poppendiek of Geoscience Ltd. of San Diego, CA, seems to suggest that the SpaCap provides about ten times more insulation capability than a rigid foam cover. But if you read it carefully, it’s actually incomprehensible.

So I wrote to Dr. Poppendiek, asking what the story was. He replied that something was radically wrong with the information on SpaCap's website. It was not in conformance, he said, with the technical data Geoscience Ltd. supplied. Dr. Poppendiek wrote, "I'm not sure whether someone at SpaCap doesn't understand the data or whether my findings are being misrepresented."

Why did that not surprise me?

The Better Business Bureau (http://www.bbb.org/western-washington/business-reviews/spas-and-hot-tubs-supplies-and-parts/spacapcom-in-lynden-wa-13025291#ratingdetails) gives SpaCap.com the grade of F, their lowest rating. The BBB says there were 41 complaints filed against the company, which failed to resolve or even respond to a significant number of the complaints.

If you Google "spa cap," you'll find websites such as www.doityourself.com, which feature numerous other extremely negative reviews such as mine.

In sum, SpaCap's product is lousy and may actually be fraudulent, and their customer skills are even worse.

[Roger]

Spa covers of thick rigid foam gradually get waterlogged and cave in, like mine did. So when I saw an ad for an innovative design at SpaCap.com, I got interested. The Spa Cap is essentially a large air bladder enclosed in a couple of layers of heavy-duty marine vinyl, so it sounds like a promising product.

It is not. Its insulation qualities are close to nil, and worse, the company's got the worst customer service this side of Attila the Hun.

I bought a Spa Cap, and after watching the company's online instructional video, I installed the cover appropriately. From that day, our electric bill skyrocketed. During the previous year, when we used a foam cover, our electric bill averaged $100 per month. With the SpaCap in place, our first month bill was $177, the second was $362, and the third, $571!

Of course, I turned off the tub and phoned SpaCap. I left several messages and then e-mails, and never got a response. I finally reached a woman in SpaCap's office, having possibly caught her off guard. She listened to me and asked me to send them a photo of the installation. I did that the same day, waited a week, and then began calling and e-mailing once again. Finally I reached the same woman. She told me the company's president had concluded I hadn't tacked the cover down with enough fasteners, and he'd already shipped me more fasteners. I'm glad I didn't wait by my mailbox.

I returned the cover to SpaCap, enclosing a request for a refund under the warranty, which covers workmanship and materials for three years. Since it didn't insulate worth a fig, it wasn't a genuine spa cover, so was completely defective. As you might guess, I heard nothing further from them.

If you go to SpaCap's website, a subpage, "R-Factor Testing Results," offers data on the product's insulation capability. The study, done by Dr. H.F.Poppendiek of Geoscience Ltd. of San Diego, CA, seems to suggest that the SpaCap provides about ten times more insulation capability than a rigid foam cover. But if you read it carefully, it’s actually incomprehensible.

So I wrote to Dr. Poppendiek, asking what the story was. He replied that something was radically wrong with the information on SpaCap's website. It was not in conformance, he said, with the technical data Geoscience Ltd. supplied. Dr. Poppendiek wrote, "I'm not sure whether someone at SpaCap doesn't understand the data or whether my findings are being misrepresented."

Why did that not surprise me?

The Better Business Bureau (http://www.bbb.org/western-washington/business-reviews/spas-and-hot-tubs-supplies-and-parts/spacapcom-in-lynden-wa-13025291#ratingdetails) gives SpaCap.com the grade of F, their lowest rating. The BBB says there were 41 complaints filed against the company, which failed to resolve or even respond to a significant number of the complaints.

If you Google "spa cap," you'll find websites such as www.doityourself.com, which feature numerous other extremely negative reviews such as mine.

In sum, SpaCap's product is lousy and may actually be fraudulent, and their customer skills are even worse.

How any advertising could convince anyone how air (the absolute worst insulator in the world) could do any insulating is behond me.

[bart6453]

Spa covers of thick rigid foam gradually get waterlogged and cave in, like mine did. So when I saw an ad for an innovative design at SpaCap.com, I got interested. The Spa Cap is essentially a large air bladder enclosed in a couple of layers of heavy-duty marine vinyl, so it sounds like a promising product.

It is not. Its insulation qualities are close to nil, and worse, the company's got the worst customer service this side of Attila the Hun.

I bought a Spa Cap, and after watching the company's online instructional video, I installed the cover appropriately. From that day, our electric bill skyrocketed. During the previous year, when we used a foam cover, our electric bill averaged $100 per month. With the SpaCap in place, our first month bill was $177, the second was $362, and the third, $571!

Of course, I turned off the tub and phoned SpaCap. I left several messages and then e-mails, and never got a response. I finally reached a woman in SpaCap's office, having possibly caught her off guard. She listened to me and asked me to send them a photo of the installation. I did that the same day, waited a week, and then began calling and e-mailing once again. Finally I reached the same woman. She told me the company's president had concluded I hadn't tacked the cover down with enough fasteners, and he'd already shipped me more fasteners. I'm glad I didn't wait by my mailbox.

I returned the cover to SpaCap, enclosing a request for a refund under the warranty, which covers workmanship and materials for three years. Since it didn't insulate worth a fig, it wasn't a genuine spa cover, so was completely defective. As you might guess, I heard nothing further from them.

If you go to SpaCap's website, a subpage, "R-Factor Testing Results," offers data on the product's insulation capability. The study, done by Dr. H.F.Poppendiek of Geoscience Ltd. of San Diego, CA, seems to suggest that the SpaCap provides about ten times more insulation capability than a rigid foam cover. But if you read it carefully, it’s actually incomprehensible.

So I wrote to Dr. Poppendiek, asking what the story was. He replied that something was radically wrong with the information on SpaCap's website. It was not in conformance, he said, with the technical data Geoscience Ltd. supplied. Dr. Poppendiek wrote, "I'm not sure whether someone at SpaCap doesn't understand the data or whether my findings are being misrepresented."

Why did that not surprise me?

The Better Business Bureau (http://www.bbb.org/western-washington/business-reviews/spas-and-hot-tubs-supplies-and-parts/spacapcom-in-lynden-wa-13025291#ratingdetails) gives SpaCap.com the grade of F, their lowest rating. The BBB says there were 41 complaints filed against the company, which failed to resolve or even respond to a significant number of the complaints.

If you Google "spa cap," you'll find websites such as www.doityourself.com, which feature numerous other extremely negative reviews such as mine.

In sum, SpaCap's product is lousy and may actually be fraudulent, and their customer skills are even worse.

How any advertising could convince anyone how air (the absolute worst insulator in the world) could do any insulating is behond me.

While I agree it's a crappy product....Air is by far not the worst insulator in the world.

Silver is about the worst...air is well....about the best.....argon is a little better.

For the record air is about 17,825 times better at insulating than silver.

For air to be an effective insulator one needs to keep it confined to an area where convection and currents cannot occur. Typically about the size of a pea. Large air chambers will begin to have convection currents and this will cause heat loss.

[hot_water]

Spa covers of thick rigid foam gradually get waterlogged and cave in, like mine did. So when I saw an ad for an innovative design at SpaCap.com, I got interested. The Spa Cap is essentially a large air bladder enclosed in a couple of layers of heavy-duty marine vinyl, so it sounds like a promising product.

It is not. Its insulation qualities are close to nil, and worse, the company's got the worst customer service this side of Attila the Hun.

I bought a Spa Cap, and after watching the company's online instructional video, I installed the cover appropriately. From that day, our electric bill skyrocketed. During the previous year, when we used a foam cover, our electric bill averaged $100 per month. With the SpaCap in place, our first month bill was $177, the second was $362, and the third, $571!

Of course, I turned off the tub and phoned SpaCap. I left several messages and then e-mails, and never got a response. I finally reached a woman in SpaCap's office, having possibly caught her off guard. She listened to me and asked me to send them a photo of the installation. I did that the same day, waited a week, and then began calling and e-mailing once again. Finally I reached the same woman. She told me the company's president had concluded I hadn't tacked the cover down with enough fasteners, and he'd already shipped me more fasteners. I'm glad I didn't wait by my mailbox.

I returned the cover to SpaCap, enclosing a request for a refund under the warranty, which covers workmanship and materials for three years. Since it didn't insulate worth a fig, it wasn't a genuine spa cover, so was completely defective. As you might guess, I heard nothing further from them.

If you go to SpaCap's website, a subpage, "R-Factor Testing Results," offers data on the product's insulation capability. The study, done by Dr. H.F.Poppendiek of Geoscience Ltd. of San Diego, CA, seems to suggest that the SpaCap provides about ten times more insulation capability than a rigid foam cover. But if you read it carefully, it’s actually incomprehensible.

So I wrote to Dr. Poppendiek, asking what the story was. He replied that something was radically wrong with the information on SpaCap's website. It was not in conformance, he said, with the technical data Geoscience Ltd. supplied. Dr. Poppendiek wrote, "I'm not sure whether someone at SpaCap doesn't understand the data or whether my findings are being misrepresented."

Why did that not surprise me?

The Better Business Bureau (http://www.bbb.org/western-washington/business-reviews/spas-and-hot-tubs-supplies-and-parts/spacapcom-in-lynden-wa-13025291#ratingdetails) gives SpaCap.com the grade of F, their lowest rating. The BBB says there were 41 complaints filed against the company, which failed to resolve or even respond to a significant number of the complaints.

If you Google "spa cap," you'll find websites such as www.doityourself.com, which feature numerous other extremely negative reviews such as mine.

In sum, SpaCap's product is lousy and may actually be fraudulent, and their customer skills are even worse.

How any advertising could convince anyone how air (the absolute worst insulator in the world) could do any insulating is behond me.

While I agree it's a crappy product....Air is by far not the worst insulator in the world.

Silver is about the worst...air is well....about the best.....argon is a little better.

For the record air is about 17,825 times better at insulating than silver.

For air to be an effective insulator one needs to keep it confined to an area where convection and currents cannot occur. Typically about the size of a pea. Large air chambers will begin to have convection currents and this will cause heat loss.

Silver is the worst insulating metal (highest thermal conductivity). But actually, diamond is by far the worst thermal insulator, having the highest thermal conductivity of any material occuring in nature. Diamond is one of a relatively few materials that is an electrical insulator and a thermal conductor. Not really relevent to spas... but an interesting factoid nonetheless.

But as Bart says, the problem with this spacap deal is that the chambers are large relative to the boundary layer that forms due to the convection currents.

I had to laugh at the argument that conventional covers lose heat due to evaporation. Spas are kind of amazing because so little water is actually lost (i.e., you don't add water very often) as long as the cover is in good shape and making a decent seal with the lid. The only really significant evaporative loss happens when the cover is off and you're in the tub.... all that steamy vapor.

[bart6453]

Spa covers of thick rigid foam gradually get waterlogged and cave in, like mine did. So when I saw an ad for an innovative design at SpaCap.com, I got interested. The Spa Cap is essentially a large air bladder enclosed in a couple of layers of heavy-duty marine vinyl, so it sounds like a promising product.

It is not. Its insulation qualities are close to nil, and worse, the company's got the worst customer service this side of Attila the Hun.

I bought a Spa Cap, and after watching the company's online instructional video, I installed the cover appropriately. From that day, our electric bill skyrocketed. During the previous year, when we used a foam cover, our electric bill averaged $100 per month. With the SpaCap in place, our first month bill was $177, the second was $362, and the third, $571!

Of course, I turned off the tub and phoned SpaCap. I left several messages and then e-mails, and never got a response. I finally reached a woman in SpaCap's office, having possibly caught her off guard. She listened to me and asked me to send them a photo of the installation. I did that the same day, waited a week, and then began calling and e-mailing once again. Finally I reached the same woman. She told me the company's president had concluded I hadn't tacked the cover down with enough fasteners, and he'd already shipped me more fasteners. I'm glad I didn't wait by my mailbox.

I returned the cover to SpaCap, enclosing a request for a refund under the warranty, which covers workmanship and materials for three years. Since it didn't insulate worth a fig, it wasn't a genuine spa cover, so was completely defective. As you might guess, I heard nothing further from them.

If you go to SpaCap's website, a subpage, "R-Factor Testing Results," offers data on the product's insulation capability. The study, done by Dr. H.F.Poppendiek of Geoscience Ltd. of San Diego, CA, seems to suggest that the SpaCap provides about ten times more insulation capability than a rigid foam cover. But if you read it carefully, it’s actually incomprehensible.

So I wrote to Dr. Poppendiek, asking what the story was. He replied that something was radically wrong with the information on SpaCap's website. It was not in conformance, he said, with the technical data Geoscience Ltd. supplied. Dr. Poppendiek wrote, "I'm not sure whether someone at SpaCap doesn't understand the data or whether my findings are being misrepresented."

Why did that not surprise me?

The Better Business Bureau (http://www.bbb.org/western-washington/business-reviews/spas-and-hot-tubs-supplies-and-parts/spacapcom-in-lynden-wa-13025291#ratingdetails) gives SpaCap.com the grade of F, their lowest rating. The BBB says there were 41 complaints filed against the company, which failed to resolve or even respond to a significant number of the complaints.

If you Google "spa cap," you'll find websites such as www.doityourself.com, which feature numerous other extremely negative reviews such as mine.

In sum, SpaCap's product is lousy and may actually be fraudulent, and their customer skills are even worse.

How any advertising could convince anyone how air (the absolute worst insulator in the world) could do any insulating is behond me.

While I agree it's a crappy product....Air is by far not the worst insulator in the world.

Silver is about the worst...air is well....about the best.....argon is a little better.

For the record air is about 17,825 times better at insulating than silver.

For air to be an effective insulator one needs to keep it confined to an area where convection and currents cannot occur. Typically about the size of a pea. Large air chambers will begin to have convection currents and this will cause heat loss.

Silver is the worst insulating metal (highest thermal conductivity). But actually, diamond is by far the worst thermal insulator, having the highest thermal conductivity of any material occuring in nature. Diamond is one of a relatively few materials that is an electrical insulator and a thermal conductor. Not really relevent to spas... but an interesting factoid nonetheless.

But as Bart says, the problem with this spacap deal is that the chambers are large relative to the boundary layer that forms due to the convection currents.

I had to laugh at the argument that conventional covers lose heat due to evaporation. Spas are kind of amazing because so little water is actually lost (i.e., you don't add water very often) as long as the cover is in good shape and making a decent seal with the lid. The only really significant evaporative loss happens when the cover is off and you're in the tub.... all that steamy vapor.

That is interesting about diamonds, I never knew that. I bet that is why they feel so cold when you hold them in your hands....hmmm....very good factoids.

[salp]

How any advertising could convince anyone how air (the absolute worst insulator in the world) could do any insulating is behond me.

It is a misconception... air is the best insulator if it is a vaccuum state.

[Dr. Spa]

??? If there's air, it's not a vacuum.

[hot_water]

That is interesting about diamonds, I never knew that. I bet that is why they feel so cold when you hold them in your hands....hmmm....very good factoids.

Yes, that'e exactly why.

Lots of work going on for quite some time now on using vacuum deposition diamond films as thermal control elements in microchips -- mucho heat to get rid of in very small volumes. Other interesting techniques also that using phase change materials, super efficient heat pipes, etc. Even tiny refrigeration compressors that can mount on a circuit board. It's fun stuff, I worked in that area for several years.

[spatech (the unreal one)]

This is an interesting thread that will help me in my spa cover design experiments. I have concluded that I will abandon my plans for high end covers made of silver or covered in diamonds (wish I hadn't started the prototypes). I will instead work on a cover with an air chamber but will modify it to draw a vacuum in the chamber so the air can insulate better.

[bart6453]

well...now we are talking about two different things.

Air is a very good insulator...but if there is nothing at all...well then there is nothing to transfer the heat.

So yes...a vacuum is much better than air as an insulator.

However...it is extremely difficult to get a vacuum in larger spaces.

The reason why your old stanley or aladdin vacuum bottle works so well even though it has a relatively large chamber is because there is very little in the chamber.

so little in fact that currents and convection are of no consequence because there is nearly nothing to convect or to flow in currents.

Do a fun experiement (i just did as I had two vacuum bottles, one which performed well, the other did not at all, and they were identical units.) Take your nice shiny vacuum bottle, and put some hot water in it. Take the temp and set it outside (in minnesota right now that means cold) for an hour and check the temp. Then drive a nail through the side and let air in...now do the experiement over again.

In 1 hour I had a 24 degree temperature difference.

So there is a significant difference from a vacuum to air. But in most cases...air is what we have to work with. (think fiberglass matting)

[pauldee]

I'm kind of surprised that with so many posts, no one has yet mentioned using a Spa Blanket, so I'll mention it. Theoretically at least, it seems to me that a combination of insulating the surface of the water from the air space under the cover would at the very least reduce condensation. Of course, that's just my uneducated opinion. I've never tried to mount a refrigerator on to a circuit board. Which, by the way, also sounds (theoretically speaking) like a good idea too.

[spatech (the unreal one)]

I'm kind of surprised that with so many posts, no one has yet mentioned using a Spa Blanket, so I'll mention it. Theoretically at least, it seems to me that a combination of insulating the surface of the water from the air space under the cover would at the very least reduce condensation. Of course, that's just my uneducated opinion. I've never tried to mount a refrigerator on to a circuit board. Which, by the way, also sounds (theoretically speaking) like a good idea too.

Spa blankets on the water surface can work very well but many find them to be a PIA relative to using the spa so they'll always have a limited appeal. I think they're a great idea, I just know that people won't want to deal with them, especially when its cold out and they want to hop in/out of the spa and run to and from the spa.

[hot_water]

I'm kind of surprised that with so many posts, no one has yet mentioned using a Spa Blanket, so I'll mention it. Theoretically at least, it seems to me that a combination of insulating the surface of the water from the air space under the cover would at the very least reduce condensation. Of course, that's just my uneducated opinion. I've never tried to mount a refrigerator on to a circuit board. Which, by the way, also sounds (theoretically speaking) like a good idea too.

I can't comment from experience on a spa blanket, since I don't have one. It seems to me that it might help, and that it would help more if your cover was not too good or made a relatively poor seal against the lip of the shell. Some users have posted here on those, though, in the past.

One thing that I've heard is that if you get a thinner or lighter duty model, it tends to bunch up. If it does this, it's probably worthless. Users of the better/heavier models don't seem to be making this complaint. Assuming the good ones are ok, the blanket might be a pain to deal with, but depending on your cover lifter you might just be able to fold it up over the cover and get it off and on without too much additional hassle.

The miniature refrigeration systems are promising, but not a slam dunk. One problem is that high end electronics (I'm not talking about stuff you might have at your home) needs to be in an environment with a controlled humidity level. If it's too dry, the static kills the CMOS devices. So.... because the humidity is maintained in the electronics room or data center, you can't run your active refrigeration unit too cold. If anything in the system goes below the local dew point, or you get condensation. Water on the circuit boards -- not a good thing. There's other issues too, like reliability, power consumption, size (density of the electronics is a big driver, even a small refrigeration system takes up volume) but people are working on them. I think they are good for hot spots -- there are high end microprocessors out there today that dissipate well over 300 watts in a single chip, so the need is real. But personally I think that some of the alternative thermal systems have more potential. It's an interesting field.

[pauldee]

Okay, now that I know I'm not going to get flamed, I'll 'fess up and admit that I have a blanket, and I love it. I really don't know if it helps hold the heat in the water, but I sure think so. Regarding taking it off, it's cake, because being made of closed-cell foam, it is extremely light, yet fairly rigid. Once I have the cover open with the lift, I can grab the end of the blanket opposite the cover, and with one hand lift it and flip it and drop it right on top of the cover. When I go to put it back on, I just flip it off the cover and drop it on the water. It is so light and rigid, that once it's floating on the water, I can slide it around with one hand to fit it perfectly back in place. When it's cold, I'll open just one half of the cover, then lift the corner of the blanket, and actually slide in and sit under the blanket. It's like tucking yourself into bed.

[Dr. Spa]

Spa blankets on the water surface can work very well but many find them to be a PIA relative to using the spa so they'll always have a limited appeal. I think they're a great idea, I just know that people won't want to deal with them, especially when its cold out and they want to hop in/out of the spa and run to and from the spa.

One spa manufacture is going to begin including a custom, cut-to-fit, 1/4" thick, floating blanket on their higher end spas very soon. Hopefully this will lead to other spa manufacturers following suit (GAWD I hope so...gotta pay for a $51k CnC machine, to cut the things, some how).

[Roger]

Silver is about the worst...air is well....about the best.....argon is a little better.

Wait a minute now!! Use some air for insulation and see how good it works!!!! I'm not talking about air inside a sealed chamber or air between two panes of glass or small air pockets in foam insulation...I'm talking AIR all by itself no matter what it consists of will not insulate. Here, take a garbage bag and fill it with air and measure the temp of the air inside the garbage bag. Then measure the air outside the garbage bag and tell me what your findings are!! Put your remote sensor inside the bag, tie off the top and place it outside. wait an hour. Now just put the sensor outside the bag and tell me what the difference is. You may be suprised that the insulating value of air is R-0. Argon slows convection between hot on one side and cold on the other but does not insulate. Put it outside and it will instantly become as cold as the outside air. It WILL NOT retain any heat.

Read my statement carefully and maybe it will become clearer.

[Dr. Spa]

Here, take a garbage bag and fill it with air and measure the temp of the air inside the garbage bag. Then measure the air outside the garbage bag and tell me what your findings are!!

My findings are the insulation value of the garbage bag

About R-0.85

[hot_water]

Silver is about the worst...air is well....about the best.....argon is a little better.

Wait a minute now!! Use some air for insulation and see how good it works!!!! I'm not talking about air inside a sealed chamber or air between two panes of glass or small air pockets in foam insulation...I'm talking AIR all by itself no matter what it consists of will not insulate. Here, take a garbage bag and fill it with air and measure the temp of the air inside the garbage bag. Then measure the air outside the garbage bag and tell me what your findings are!! Put your remote sensor inside the bag, tie off the top and place it outside. wait an hour. Now just put the sensor outside the bag and tell me what the difference is. You may be suprised that the insulating value of air is R-0. Argon slows convection between hot on one side and cold on the other but does not insulate. Put it outside and it will instantly become as cold as the outside air. It WILL NOT retain any heat.

Read my statement carefully and maybe it will become clearer.

Roger, a material's value as an insulator is determined by a property called thermal conductivity. Bart is just quoting the facts. Air has a very low thermal conductivity, which makes it an excellent insulator. It is better than most common solid materials, it is better than most liquids, it is even better than most other gasses. Bart pointed that out, and he is right.

You are right in that a mass of air is not as effective and a well designed insulation system such as foam. You however should not be comparing a single material, be it air, argon, water or whatever, to a system such as a piece of foam, which exploits the excellent thermal properties of air and uses the foam matrix to defeat the convection currents. Different animals - and that was, I think, Bart's point. You might want to think about the effectiveness of a foam cover that becomes saturated with water. Water is actually a very much worse thermal insulator than air (better thermal conductor) so when water replaces air in the cover, the performance becomes unacceptable. Get the point? You said air was the worst thermal insulator, but in fact it IS one of the best.

Your example is not really relevant to demonstrate air as a poor insulator. What your thought experiment demonstrates is a different property, namely, the low heat capacity of air. It is true that it doesn't take a lot of thermal energy to bring air up to temperature. That particular property is very important in some designs such as the perimeter insulation spas, since as cabinet air gets close in temp to the shell, very little heat flow takes place. So, you are really demonstrating a property of air that can be taken advantage of to make an even better insulting system, not demonstrating at all that air is a poor insulator. Your suggested experiment points out a big reason why those designs - using air as one element of the insulation system in concert with the perimeter foam - can work very well. This and your comments on argon indicate that you're not fully understanding the concepts of heat conduction, insulation and heat capacity, all of which are different.

In other words, don't jump on Bart... he's right.

[bart6453]

Silver is about the worst...air is well....about the best.....argon is a little better.

Wait a minute now!! Use some air for insulation and see how good it works!!!! I'm not talking about air inside a sealed chamber or air between two panes of glass or small air pockets in foam insulation...I'm talking AIR all by itself no matter what it consists of will not insulate. Here, take a garbage bag and fill it with air and measure the temp of the air inside the garbage bag. Then measure the air outside the garbage bag and tell me what your findings are!! Put your remote sensor inside the bag, tie off the top and place it outside. wait an hour. Now just put the sensor outside the bag and tell me what the difference is. You may be suprised that the insulating value of air is R-0. Argon slows convection between hot on one side and cold on the other but does not insulate. Put it outside and it will instantly become as cold as the outside air. It WILL NOT retain any heat.

Read my statement carefully and maybe it will become clearer.

Roger, a material's value as an insulator is determined by a property called thermal conductivity. Bart is just quoting the facts. Air has a very low thermal conductivity, which makes it an excellent insulator. It is better than most common solid materials, it is better than most liquids, it is even better than most other gasses. Bart pointed that out, and he is right.

You are right in that a mass of air is not as effective and a well designed insulation system such as foam. You however should not be comparing a single material, be it air, argon, water or whatever, to a system such as a piece of foam, which exploits the excellent thermal properties of air and uses the foam matrix to defeat the convection currents. Different animals - and that was, I think, Bart's point. You might want to think about the effectiveness of a foam cover that becomes saturated with water. Water is actually a very much worse thermal insulator than air (better thermal conductor) so when water replaces air in the cover, the performance becomes unacceptable. Get the point? You said air was the worst thermal insulator, but in fact it IS one of the best.

Your example is not really relevant to demonstrate air as a poor insulator. What your thought experiment demonstrates is a different property, namely, the low heat capacity of air. It is true that it doesn't take a lot of thermal energy to bring air up to temperature. That particular property is very important in some designs such as the perimeter insulation spas, since as cabinet air gets close in temp to the shell, very little heat flow takes place. So, you are really demonstrating a property of air that can be taken advantage of to make an even better insulting system, not demonstrating at all that air is a poor insulator. Your suggested experiment points out a big reason why those designs - using air as one element of the insulation system in concert with the perimeter foam - can work very well. This and your comments on argon indicate that you're not fully understanding the concepts of heat conduction, insulation and heat capacity, all of which are different.

In other words, don't jump on Bart... he's right.

+1

You are getting specific heat confused with thermal conductivity.

You can wiki both.

Lets not beat this dead horse any more.....we all know that damn cover is not going to work.

Now that we all agree....lets put it to bed.

[hot_water]

+1

You are getting specific heat confused with thermal conductivity.

You can wiki both.

Lets not beat this dead horse any more.....we all know that damn cover is not going to work.

Now that we all agree....lets put it to bed.

Just for those that may not be fully familiar with such things....

My reference to "heat capacity" and Bart's to "specific heat" refer to the same physical property... just different ways of expressing the property numerically.

Bart.... I agree. But it is fun to bust Roger's chops once in a while.