Hot Tub Cover Thicknes And Weight Question

[cnw]

My cover is about 5 years old and extremely heavy so I figure it's time for a new one, or at least a new core, since the cover is still in good shape. Just went to Home Depot and found R10 foam insulation that may work but upon looking at new covers online I see that the cheapest one I could buy is R15. Seems like now it's worth buying a new cover since I'll spend more heating it going the cheap route - I live in Albany NY. To make a long story short, what's more important - the thickness or weight of the core and what do I really need where I live. My original cover is 3.5 inches tapering to 2.5 inches. Thanks.

[Dr. Spa]

R value is based on a combination of the weight (density) of the foam, AND it's thickness.

"What is the R-value of your cover"? While this is the most common question asked when comparing covers, the answer can be the most deceptive. The following, though rather lengthy, explains insulation and R-value.

The insulating core of almost all spa covers is EPS (Expanded Polystyrene). The insulating value of this product is very specific, and is listed in the table below. Please note, the R-value shown is for 1 inch of thickness.

Foam Density -- R-Value/in.

1.0 -- 3.85

1.25 -- 4.0

1.5 -- 4.17

2.0 -- 4.35

Remember, all EPS foam of equal density has the same R-value!

R-value describes a material's resistance to the flow of heat. The higher the R-value, the slower heat will travel or conduct through a material. Better insulating materials tend to have better R-values.

Heat flows by three mechanisms: conduction, convection, and radiation;

Conduction

is the molecule-to-molecule transfer of kinetic energy (one molecule becomes energized and, in turn, energizes adjacent molecules). A cast-iron skillet handle heats up because of conduction through the metal.

Convection

is the transfer of heat by physically moving the molecules from one place to another. Hot air rises; heated water thermosiphons; forced-air heating systems work by moving hot air from one place to another.

Radiation

is the transfer of heat through space via electromagnetic waves (radiant energy). A campfire can warm you even if there is wind between you and the fire, because radiation is not affected by air.

R-values by definition, only measures an insulation's ability to resist heat loss by CONDUCTION.

The above's relationship to spas is this; heat from the spa water rises by convection and radiation. As it rises it heats the underside of the cover, then moves through the cover by conduction. Increasing the covers R-value reduces, or slows the rate of conduction.

R-value is a term coined by the FTC in response to a need for a way to compare the relative effectiveness of various forms of insulation. R-values are measured by testing laboratories (ASTM), usually in something called a guarded hot box. As air within the test hot box is heated, convection takes place, causing the heat to rise. As the heat rises it warms the underside of the foam where upon conduction of the heat through the foam begins. The R-value is the ability of the foam (or other material being tested) to slow this conduction. Heat flow through the foam is calculated by keeping one side of the material at a constant temperature, say 90°F (32°C), and measuring how much supplemental energy is required to keep the other side of the material at a different constant temperature, say 50°F (10°.C)--

Various industries are required to have their products R-value tested by ASTM under very exact testing perimeters. One of the parameters of this test is the temperature at which guarded hot box is heated to, AND the temperature the other side of the test material is kept at. Changing either of these temperatures will result in different R-value results. Once again, certain industries are required to use ASTM testing procedure and parameters. For these industries, when they list their products R-value (such as R-20) it's understood that the difference in temperatures of the testing procedure is 40 degrees (e.g. R-20 @ 40º). It's also acceptable to list another R-value AS LONG as the temperature difference is listed ALSO (i.e. R-40 @ 20º). Here's the relationship to spa covers. SPA COVERS ARE NOT IN AN INDUSTRY REQUIRED TO HAVE R-VALUES TESTED ACCORDING TO ASTM STANDARDS! Different spa cover sellers sometime can, and do, give different R value listings for similar covers. Remember covers of the SAME thickness and DENSITY will have the EXACT same R-value, REGARDLESS of what the seller may claim.

[cnw]

Thanks, saw a similar explanation at www.beyondnice.com, also sold on amazon, and may go with their 6" to 4" model. I do like and purchase from www.spadepot and plan to look at their lineup too. Comes down to 6" to 4" with a 1 lb. core vs 4" to 2.5" with a 2 lb. core.

[RickJ]

FYI - Dr. Spa is one of the most-knowledgeable and respected cover manufacturers around. He makes some of the best-quality covers out there, and offers excellent service. I would highly recommend checking out his site for a cover. www.rhtubs.com

[GSmith]

One thing to keep in mind is the taper from centre to outer edge. My Coyote spas came with flat covers 2" thick. I have replaced them slowly with covers that are 4" at the center tapering to 3" at outer edge.

This helps with shedding rain and melting snow and the thickness sure makes a dif in winter heating.

My cover is about 5 years old and extremely heavy so I figure it's time for a new one, or at least a new core, since the cover is still in good shape. Just went to Home Depot and found R10 foam insulation that may work but upon looking at new covers online I see that the cheapest one I could buy is R15. Seems like now it's worth buying a new cover since I'll spend more heating it going the cheap route - I live in Albany NY. To make a long story short, what's more important - the thickness or weight of the core and what do I really need where I live. My original cover is 3.5 inches tapering to 2.5 inches. Thanks.

[Shaamus]

For energy-efficiency, you get more bang for the buck with thicker foam. However, denser foam absorbs less water and you'll end up using the cover longer. A 4x2 2# foam cover has more foam (192 boardfeet per side) than a 6x4 1# foam cover (160 boardfeet per side) but the 6x4-1 is much almost 50% more energy-efficient. It's just going to take on a lot more water as it has more foam and more places in between the beads. Just depends on what you are shopping for.

[cnw]

I would think energy efficiency is the top priority since the money you save heating the tub in upstate NY would more than offset the life of the cover as long as I get a 5 year warranty? In that case I think a 5"/3" with 1.5 lb foam would be better than a 4"/2" with 2 lb foam right? Thanks.

[countspacula]

I would think energy efficiency is the top priority since the money you save heating the tub in upstate NY would more than offset the life of the cover as long as I get a 5 year warranty? In that case I think a 5"/3" with 1.5 lb foam would be better than a 4"/2" with 2 lb foam right? Thanks.

We manufacture covers, the thickness of the foam, past 2" makes no difference in efficiency, period. I have conducted numerous tests on this. Heavier foam adds structural integrity only, perhaps for limbs falling on it, dogs and kids on it etc....

[Dr. Spa]

I would think energy efficiency is the top priority since the money you save heating the tub in upstate NY would more than offset the life of the cover as long as I get a 5 year warranty? In that case I think a 5"/3" with 1.5 lb foam would be better than a 4"/2" with 2 lb foam right? Thanks.

What exactly do you expect the warranty to cover? And with what exclusions?

5x3 with 1.5 pound foam has an R value of R-18. 4x2 with 2 pound foam is R-15.

Strength wise, as far as the amount of weight they'll hold, the difference is less than 1%.

In terms of the actual weight of the cover, they both weigh the same.

[Dr. Spa]

We manufacture covers, the thickness of the foam, past 2" makes no difference in efficiency, period. I have conducted numerous tests on this. Heavier foam adds structural integrity only, perhaps for limbs falling on it, dogs and kids on it etc....

So R value has no meaning? Or are you saying that increasing the thickness of the cover doesn't increase the R value?

Building codes in my area require my home to have attic insulation of at least R-30. My house is only heated to about 70 degrees. My hot tub 34 degrees hotter.

[countspacula]

We manufacture covers, the thickness of the foam, past 2" makes no difference in efficiency, period. I have conducted numerous tests on this. Heavier foam adds structural integrity only, perhaps for limbs falling on it, dogs and kids on it etc....

So R value has no meaning? Or are you saying that increasing the thickness of the cover doesn't increase the R value?

Building codes in my area require my home to have attic insulation of at least R-30. My house is only heated to about 70 degrees. My hot tub 34 degrees hotter.

R values arent usually mentioned in regards to covers, but a 2# foamed cover is heavier in weight than a 1# one. Guaranteed, put a 1.5# cover on your tub, run it for a month and monitor cost, the cost will be the same if you had a 500# cover

[Dr. Spa]

R values arent usually mentioned in regards to covers

wtf?

[countspacula]

R values arent usually mentioned in regards to covers

wtf?

www.nashvillespacovers.com, www.thecoverguy.com, www.thespacap.com. Just a few major cover suppliers, R value not even mentioned. Basically a 4-2 1.5# has an R of 17 and a 5or6-3 2# has R of 19 plain and simple, that small an R difference is not much in savings, density is upgraded to tolerate weight, freeze cracking, etc.

[Dr. Spa]

Major? :lol: :lol: :lol:

[Roger]

R values arent usually mentioned in regards to covers

wtf?

Spa Cap are you kidding me?????? Air for insulation???? No wonder they don't mention R-Factor. There is none!!

[countspacula]

R values arent usually mentioned in regards to covers

wtf?

Spa Cap are you kidding me?????? Air for insulation???? No wonder they don't mention R-Factor. There is none!!

All spa covers use air as help in insulating, except floaters. foam core covers dont sit in contact with the water do they??

[countspacula]

laugh all you want to, but even your own website backs this up, im done with it.

[Dr. Spa]

ummmmmm, yeah

www.rhtubs.com/covers/insulate.htm

"Tapered for rain water run-off, low center deflection value, excellent strength while still light weight, and the best R value in the industry!"

:lol::lol:

[Dr. Spa]

Spa Cap are you kidding me?????? Air for insulation???? No wonder they don't mention R-Factor. There is none!!

Here's my favorite review of them;

From Tom G

I am a long time Spa owner and when it was time to replace yet another foam filled traditional hot tub cover I decided to take a look on the web for some new ideas or maybe a good deal on a cover. If you do a simple hot tub cover Google search you will surely come across the SPACAP by Another Company. The problem I had was that no other info was available about this product except what the maker had on his site. I read through his info and it sounded great. Supposedly more efficient than traditional covers and it will last longer. The theory made sense to me but I couldn't figure out if this was such a great idea why 25 other companies weren't offering the same thing. I tried to research and talked with as many knowledgeable people as I could with no definitive opinions anywhere. So I bit the hook and bought one.

I ordered it in the fall of 2004. I am writing this opinion in December of 05. I have owned it 18 months or so.

The cover came from the manufacturer quickly and was well constructed with a perfect fit. But the jury was still out as to wether an air bag works as well as foam insulation. The first thing I noticed was that snow (I am in Wisconsin) never accumulated on the Spacap. I used to have to sweep snow off the top of my traditional cover after every storm. But snow melted off the Spacap as fast as it fell.....HMMMMM.

Next I noticed my spa pump running more and my electric consumption never went down. Contrarily my power consumption went up.

I still needed more concrete evidence. A bit more scientific. Here is what I did......You be the judge.

I got a thermal imaging camera. This is used by energy annalists to check homes for heat loss and efficiency. It is also used by Fire Departments to check for hot spots in burning buildings. It uses infrared technology to get spot on accuracy. The camera allows you to point at any object and get a pinpoint temperature reading of the object.

I did the test on a day that the outside air temperature was 12 degrees. The thermal camera was reading ambient objects at around 14 degrees. It was reading the outside of houses at 19 degrees. Now the big moment...... lets point this puppy at the Spacap. It read 40 degrees. What? Yes 40 degrees. The hot tub water is at 100 degrees. Gad that doesn't seem good at all. One last test to do. I needed to compare it to a foam cover. So to the neighbors yard I went. I turned the camera on to a traditional foam cover with a 102 degree hot tub. The camera read 19 degrees.

Needless to say I am seriously bummed out that I got taken by a slick web site. I like to think I am smarter than the average bear. Anyway I felt I needed to post this info to the web so others can have a fair opinion before spending $400 or more on a Spacap.

[Roger]

R values arent usually mentioned in regards to covers

wtf?

Spa Cap are you kidding me?????? Air for insulation???? No wonder they don't mention R-Factor. There is none!!

All spa covers use air as help in insulating, except floaters. foam core covers dont sit in contact with the water do they??

Tiny air pockets in foam insulation are a completely different concept. If you need explanation on this and how it works I think maybe you are out of your league here.

[countspacula]

none better to get explanations from than the one that has an answer for everything and knows all about all.