Are you in the industry? You seem pretty knowledgeable for just your average hot tub owner?
All Spa Owners Should read this: Valuable Lesson Learned: ALWAYS Pull hot tub cover cores out and check them when you receive a new cover
- Thread starter DangerBoy
- Start date
Nope, not in the industry. I'm a professional engineer working in the environmental consulting industry. Being a geological engineer, I have an extensive background in hydrogeology which is the study of the movement of groundwater through porous rocks and soil. In other words, the movement of water through porous media. The same principles apply whether you're talking about the infiltration and movement of water through porous sandstone or styrofoam. To me, a low permeability clay layer sitting atop a porous and permeable sandstone or gravel layer and insulating/protecting it from the downward migration of a contaminant under the force of gravity is the exact same thing as a water resistant poly sheet being wrapped around a porous polystyrene board in order to slow down the rate at which water infiltrates the board in a high vapour pressure environment. It's pretty much the exact same thing happening in both cases, just different physical settings.
My engineering education also gave me a little background in electricity and circuit design and my own curiousity and fascination for figuring out how things work coupled with the diverse and well rounded education I got in engineering school has enabled me to understand how my hot tub's control systems work and since all hot tubs generally work the same way, I can apply this understanding to other hot tub control systems.
My engineering education also gave me a little background in electricity and circuit design and my own curiousity and fascination for figuring out how things work coupled with the diverse and well rounded education I got in engineering school has enabled me to understand how my hot tub's control systems work and since all hot tubs generally work the same way, I can apply this understanding to other hot tub control systems.
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Good info @DangerBoy, thanks for enlightening and educating us on these covers.
Funny thing is, they DO openly admit that the covers only last at best 4 years. I’ve been shopping for a hot tub, and this has been the info pretty much across the board.
Funny thing is, they DO openly admit that the covers only last at best 4 years. I’ve been shopping for a hot tub, and this has been the info pretty much across the board.
@ArizonaBob There are 2 or 3 companies making covers that don't use styrofoam cores and will last 10+ years but they cost 4 - 6 times more than a standard cover. I didn't even consider them as they're US based companies and shipping costs to Canada would've been enormous. Might be worth considering if you're located in the lower 48.
I never realized that having your cover get waterlogged was a thing. How does one know when it needs to be replaced? Mine tub is almost 3 years old.
When the covers are new they are very light. You can flip a side open with just a couple of fingers. Then, they very gradually get heavier as they absorb more and more water. The weight gain is so gradual you might not even notice it's happening. Then, after 4 or 5 years, they are usually quite heavy. My tub is fairly large (99" x 92") so the cover is large too but the last cover I had was extremely heavy. I bet it weighed at least 60 lbs but it may have been quite a bit more than that. I should've replaced it long before it got that bad but I had no money so I just lived with it and made it work well beyond its useful life.
I'm not sure of this but I suspect that the rate at which covers get waterlogged may be highly dependent on the climate the cover "lives" in and whether the tub is kept sheltered or indoors or fully exposed to the elements, etc. I know the climate I live in is pretty tough on covers and they get waterlogged pretty fast here. A mild dry climate may help them last longer than they typically do here.
I'm not sure of this but I suspect that the rate at which covers get waterlogged may be highly dependent on the climate the cover "lives" in and whether the tub is kept sheltered or indoors or fully exposed to the elements, etc. I know the climate I live in is pretty tough on covers and they get waterlogged pretty fast here. A mild dry climate may help them last longer than they typically do here.
Usually the cores are zippered into the covers. The zippers run along the inside of the fold. You could try pulling them out, removing the LDPE wraps and letting them bake in your hot Arizona sun for a while! You might not get all of the water out but you'll definitely get some after a few days of drying in the hot sun. You could maybe speed the process a little and improve results by using fans to blow air across the surfaces of the cores as they bake. The more hot drying air you can get moving across the surfaces of the core to draw moisture out, the better.
If you cut the wrap with a sharp razor knife along the narrow end of the core, you can minimize the length of the cut needed to allow you to slide the core out of the wrap. You could then reuse the wrap by sealing it back up with a proper waterproof tape like Nashua waterproofing repair tape (Home Depot) which is a metalized polypropylene tape which should be at least as moisture resistant as the LDPE wrap if not more. This might help you get a few more years out of your cores.
If you cut the wrap with a sharp razor knife along the narrow end of the core, you can minimize the length of the cut needed to allow you to slide the core out of the wrap. You could then reuse the wrap by sealing it back up with a proper waterproof tape like Nashua waterproofing repair tape (Home Depot) which is a metalized polypropylene tape which should be at least as moisture resistant as the LDPE wrap if not more. This might help you get a few more years out of your cores.
@Pool_Medic I finally pushed my old hot tub cover off the tub and replaced it with the new one. The dimensions of the old cover were 99" x 92" so on the big side as spa covers go and appeared to have a 3.5" to 3" taper but maybe it was originally a 4" to 3" taper. I think the previous owner of the tub bought the cover from Watkins so I'm not sure what amount of taper they give their covers. Whatever the taper was, it wasn't enough as rain water used to pool on top of the cover and not run off. I had to push the water off it with a plastic bladed snow shovel. My new cover has a 5" to 3" taper so I shouldn't have that problem anymore.
The old cover was so saturated and heavy that I (5' 9" 180 lbs) and my friend (5' 11" 200 lbs) could barely lift it and carry it away from the hot tub. Neither of us are champion weight lifters by any means but we're not weak either. I'd say I have average strength for a man my size and my friend is a little stronger than average for his size. I brought out my bathroom scale and we struggled to get the cover set and balanced on it but when we did the scale read somewhere in the range of 195 - 200 lbs!! Astonishing!
We've started cutting the core up for gradual disposal in my city black bin. Each little chunk of styrofoam from the core I throw in the bin just oozes and drips water out of all its pores and literally weighs about as much as what you'd expect the chunk would weigh if it was 100% water and no styrofoam. Obviously, that's not the case but you'd be surprised how heavy the chunks are considering the matrix is just styrofoam.
The old cover was so saturated and heavy that I (5' 9" 180 lbs) and my friend (5' 11" 200 lbs) could barely lift it and carry it away from the hot tub. Neither of us are champion weight lifters by any means but we're not weak either. I'd say I have average strength for a man my size and my friend is a little stronger than average for his size. I brought out my bathroom scale and we struggled to get the cover set and balanced on it but when we did the scale read somewhere in the range of 195 - 200 lbs!! Astonishing!
We've started cutting the core up for gradual disposal in my city black bin. Each little chunk of styrofoam from the core I throw in the bin just oozes and drips water out of all its pores and literally weighs about as much as what you'd expect the chunk would weigh if it was 100% water and no styrofoam. Obviously, that's not the case but you'd be surprised how heavy the chunks are considering the matrix is just styrofoam.
Explain why styrofoam inserts for lights and skimmers do not absorb any water after being immersed under water for 6 plus months? Yes I use them on some pools for closings. Every piece of foam I’ve looked at would not retain water.
It all apparently depends on the density of the styrofoam plus possibly a sealant that Dow uses. Styrofoam is used as billets for floating docks, consequently it can be made virtually waterproof - somehow. I've tried for about half an hour to get some hard spec data but have been unsuccessful.
I'm a first time spa owner (due to arrive end of month) and have been considering methods of heat retention (we plan on using it year round) and cover life extension. If practical, I plan on getting a 1 or 2 in. sheet of rigid foam board (OC Foamular from Home Depot) with a R value of 5 per inch., cut to form and float it. My spa will have a 4 / 2 taper cover. Depending on foam density, these covers have R values of 12 to 15. A 2" sheet is about 40 bucks and would nearly double the system R value. My tub is full foam, so my heat loss will be vertical for all practical purposes.
I'm a first time spa owner (due to arrive end of month) and have been considering methods of heat retention (we plan on using it year round) and cover life extension. If practical, I plan on getting a 1 or 2 in. sheet of rigid foam board (OC Foamular from Home Depot) with a R value of 5 per inch., cut to form and float it. My spa will have a 4 / 2 taper cover. Depending on foam density, these covers have R values of 12 to 15. A 2" sheet is about 40 bucks and would nearly double the system R value. My tub is full foam, so my heat loss will be vertical for all practical purposes.
Interesting note. Check out the Cole-Palmer Chemical Compatibility Database. If you enter in LDPE (The material hot tub cover manufacturers use for a vapor barrier around cover cores) you can see that its compatibility with Bromine is poor and with chlorine water is good with a footnote that says "Satisfactory up to 72F/22C". It would seem then that LDPE is a poor choice for core wrap material in spa covers. Perhaps if another wrap material was used, the cores could be made to last longer. Unfortunately, the database doesn't have a rating for HDPE to compare but maybe others do.
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Fascinating thread here! I recently replaced my cover - I am on about the 3rd cover in my ~13 years of owning a spa. My old cover was extremely heavy. I tried to dry the styrofoam out by leaving it out in the sun for a few days to make it easier to carry to the garbage but it was still extremely heavy. And my hot tub is only 7' x 7' so each big piece of styrofoam would have only been 3.5' x 7'. Luckily the city of Toronto took the cover on my garbage day - they take large items if you leave them out.