Suggestions for a large spa cover?

[uncle K]

We have an association owned, in-ground hot tub, heated by gas. Considering how little it actually gets used, it costs plenty to keep it up and running. We use a blue, bubble tarp to cover it when not in use, which helps limit heat loss, but I believe we could do better. The combination of hot water, chemicals and especially the intense sun deteriorates these wimpy blue tarps pretty fast.

This is located in the sunniest place on the planet, so a solar cover of some sort seems like the answer. The concept is to let the sun through to heat the water naturally, while preventing the heat from escaping. This round tub measures 10' 3" diameter... larger than the market for residential spas. From the claims I've heard about solar covers, we could cut our heating bill in half, but looking around, I'm yet to find anyone who makes one that will work in this application.

Any suggestions/leads (short of filling the spa with dirt and planting flowers) would be appreciated.

Uncle K

[Home Guy]

Which would appear to be Kapolei, Hawaii.

(say hello to Barry for us).

Construct a cover out of plywood and paint it black.

Seeing that you're located in Hawaii, I would think that your heat-loss problems are minimal - assuming the sides of the tub are insulated to prevent heatloss into the surrounding soil.

Your only real alternative is to cover the tub with a glass or acrylic cover - one that won't easily break and can be easily removed when the tub is to be used.

[Dan Espen]

Blue bubble tarp _is_ a solar cover.

It combines light transparency and air trapped in the bubbles which makes for great insulation.

[gonjah]

If it were me I'd buy a solar pool cover and cut it to your size. You can even double it up. Just don't use it when you are adjusting your chemicals. Get the 16mil "backed" solar blanket. When it "wimps" out just cut another.

The other option is to go the custom cover route. Google: custom in ground spa cover.

Leaving it hot is the problem. I'd have spa hours so you can cut the heat during non use periods. With a solar cover it wouldn't take long to recover. Get a fireman switch for your spa pump and heater. BTW I use a solar cover on mine and it helps a lot but I don't leave mine hot. I heat it as I use it.

[Jim Elbrecht]

I'm guessing that's AZ? [I'm in NY, so the idea of sunshine is practically foreign to me since September or so]

Post your question to

are the guy who tells you everything you need to know is the owner of Roberts Hot tubs-- He doesn't mention it often-- but he is always there for guidance and advice.

He sells tubs and custom covers through his site-

Looks like he has a message board of his own now-- cool.

I bought a cover from him a couple years ago and it was everything he said it was-- [and there were a whole lot of satisfied customers on the poolandspa forum when I bought mine.

Jim

[gfretwell]

Solar heat is a natural for a spa. A few glazed collectors will boil that sucker for free during the day in a sunny place.

I just have unglazed pool collectors on mine and I still get 20 degrees or more over ambient air by sundown. We don't run the heat unless we want to use it but if I am over 90, the heat brings it up pretty fast and for about six bits.

[Jim Elbrecht]

How little is *little*- Are the side walls insulated from the surrounding soil? What temp is it while unused? How much does it cost?

Just as a reference- my hot tub, in NY- gets used once a day. I keep it at a steady 101F. It has a thick cover on it-- and the base is well insulated.

I heat it with electricity, at about 15cents/KwH- it costs me about $30 a month, whether it is 0F or 80F.

-snip-

But even in Yuma, the sun sets, yes? I suspect you lose more than you gain from a passive solar color-- but I haven't run the numbers.

Jim

[uncle K]

The spa and a 20' X 40' pool are available to 81 units, but only used by maybe 25% of them. The pool has a roll up cover in the winter to stay at about 82=B0. The sun heats the pool during 6 or 7 summer months (but I'm not crazy enough to be there in the summer). The spa runs

365/24/7.

We keep it at 102=B0, year round. Like everything else in the desert, the base is surrounded by sand.

It would be great to not even cover the spa, but due to long periods of non-use, it's a must. Another complication is that not just one person uncovers and covers it, so whatever we cover it with has to be relatively easy to handle, the lighter the better. Even the blue bubble tarp is a bit of a pain for older, less agile people.

;-{

[uncle K]

Not Hawaii. Near Yuma, which gets more hours of sunshine than any other inhabited place on earth. There are two places which get more sun (middle of the south Pacific Ocean and Sahara Desert), but nobody lives there. The tile over cement spa is surrounded by sand, which is about 300 feet deep.

The blue bubble tarps help, but I think we could do better, even if the initial cost is much higher. The intense sun and chemicals drastically shorten the life of the tarps, so one season is about the best we can get out of one before it gets brittle and begins to tear.

;-{

[uncle K]

Agreed, but I still think we could do better and get something that will last more than 6 months. Most of the seemingly few companies who make such covers are geared to residential, and/or square spas and don't have the ability to make a round one 10' 3" across. About the only place you'll find spas that size would be a hotel, where they don't cover the spa.

;-{

[Home Guy]

Interesting.

An IP-geolocation website I use gives your location (based on IP address) as Hawaii (with service provided by Verizon Wireless).

[uncle K]

That's what we are doing. Often, we cut a new one using the last blue bubble pool tarp. Whatever we use needs to be light enough to be manageable. The spa is serviced one a week, by our "pool boy." Otherwise, nobody touches it, except when something goes wrong.

I've looked, but haven't found the right one, yet. Short of ordering exactly the size we need, we could get an 11 footer and cut it to size.

We need to have the spa up to temperature and ready to use every day, from 6:30 AM until 10:30 PM. A timer might help a little during those off hours, but the entire pool/spa system is already pretty complicated.

;-{

[uncle K]

Even more interesting is that I'm using a Verizon broadband connection, located in Washington. I shoveled some snow this week, while thinking about a hot tub 1400 miles away.

;-{

[uncle K]

I need to go shovel some more snow so I can get my car out, but I'll look into that. Thank you.

;-{

[Home Guy]

Ah - that is interesting.

Another IP-geolocation service puts you in Portland OR.

[krw]

Denver, CO and Grand Rapids, MI, too. The dude is everywhere.

[gonjah]

I don't think a custom cover is going to be easier. The one I had was pretty heavy. It really sounds like the solar cover is the best way to go. There isn't a magic answer unless you want to spend mega bucks (some sort of auto cover or enclose the spa)

[gonjah]

Mine lasts for several years in the spa but I don't add chemicals into the spa. It might be your chemicals are eating it up. Chlorine will eat up a custom cover too. At a MUCH higher replacement cost.

Only use the cover when the chemicals are stable.

[gfretwell]

I always hear this but the laws of physics dispute it. You get the highest loss of heat when you have the greatest delta between inside and outside. All of that heat needs to be replaced, whether it leaks out slowly from cooler water or faster from 102f water so 102 constantly will cost more at the end of the day.

[gfretwell]

I have a blue bubble cover on mine and it pukes the heat out once you turn the heat off. 3 or 4 degrees an hour if the water is 35-40 above ambient air but that rate drops as the delta closes..