Pool as heat source

[Zeeth]

My mom and I were discussing plans for her next house (which will be in the 9b-ish side of Manatee county). She wants to do a planting where there is a heated pool (non screened in) with pavers around it, and a coconut palm planted on the edge of the pool sideways so that it curves and leans out over the water. I thought that this probably would create an excellent microclimate for the coconut, as the heat off the pool would warm the coco when temps drop below freezing. Would this work well? I was wondering if the steam would only create frost, or if it would protect the coconut completely from freezes so it never gets damaged. What temp do you think the pool water should be ideally during the cold days to keep frost off the coconut? I have a Pacific tall from Hawaii (from Garrin in Hawaii) that I got recently that I think would be perfect for the job. It would keep the curve longer than a Malayan, it would grow faster and be cold hardier long term than the Malayan, and it has better LY resistance than a Jamaican tall. What do you think about this?

Keith

[Tyrone]

Your idea sounds like it would work to me, but I'm not familiar with your area to know how cold you get. It also depends on how big the pool is (it's heat sink ability), it's aspect to the sun (as that would heat it up-if it's in shade it wouldn't get that warm) and whether you get advective freezes rather than radiational freezes and how far away the palm is from the pool. As it gets taller the crown will move away from the pool and away from the microclimate. In an advective freeze microclimates have less of a warming effect compared to radiational freezes. If it's heated you have an extra advantage, but energy costs can't be ignored. If it's in the best position to pick up some natural heat, on really cold events you can crank up the heating to keep it even cosier.

My thoughts are that a normal unheated sized pool in a radiational cooling situation may hold 3-4C or approx 5-8F over ambient temp. Add rocks and a rockery that's fully exposed to the winter sun and the extra thermal mass may hold more.

They're my thoughts for what it's worth.

Best regards

Tyrone

[Zeeth]

Your idea sounds like it would work to me, but I'm not familiar with your area to know how cold you get. It also depends on how big the pool is (it's heat sink ability), it's aspect to the sun (as that would heat it up-if it's in shade it wouldn't get that warm) and whether you get advective freezes rather than radiational freezes and how far away the palm is from the pool. As it gets taller the crown will move away from the pool and away from the microclimate. In an advective freeze microclimates have less of a warming effect compared to radiational freezes.

My thoughts are that a normal sized pool in a radiational cooling situation may hold 3-4C or approx 5-8F over ambient temp. Add rocks and a rockery that's fully exposed to the winter sun and the extra thermal mass may hold more.

They're my thoughts for what it's worth.

Best regards

Tyrone

In the area we are moving to, the climate is humid subtropical, with USUALLY 1 freeze every year or 2 (this year saw 5 or 6) and temps USUALLY bottom out at 30 to 32F (-1 to 0C) when it does freeze (this years minimum was about 27F (-3C)). The pool would be in full sun. We normally get only radiational freezes, adjective freezes are more rare, and tend to keep frost at bay when they aren't super cold. Very tall palms have better tolerance to cold here, so I think that when the palm grows away from it's heat source, that it would maybe be able to survive the cold. The pool will be salt water, so splashback won't hurt the palm, so it can be planted close to the pool.

[freakypalmguy]

In the California freeze 2007, many found that the plants around pools faired better than those that were not.

Matt

[Zeeth]

In the California freeze 2007, many found that the plants around pools faired better than those that were not.

Matt

Thanks, that's a good example of use in the field and not just theoretical thinking.

Anyone in somewhere like central florida every try this before?

[Tyrone]

Your idea sounds like it would work to me, but I'm not familiar with your area to know how cold you get. It also depends on how big the pool is (it's heat sink ability), it's aspect to the sun (as that would heat it up-if it's in shade it wouldn't get that warm) and whether you get advective freezes rather than radiational freezes and how far away the palm is from the pool. As it gets taller the crown will move away from the pool and away from the microclimate. In an advective freeze microclimates have less of a warming effect compared to radiational freezes.

My thoughts are that a normal sized pool in a radiational cooling situation may hold 3-4C or approx 5-8F over ambient temp. Add rocks and a rockery that's fully exposed to the winter sun and the extra thermal mass may hold more.

They're my thoughts for what it's worth.

Best regards

Tyrone

In the area we are moving to, the climate is humid subtropical, with USUALLY 1 freeze every year or 2 (this year saw 5 or 6) and temps USUALLY bottom out at 30 to 32F (-1 to 0C) when it does freeze (this years minimum was about 27F (-3C)). The pool would be in full sun. We normally get only radiational freezes, adjective freezes are more rare, and tend to keep frost at bay when they aren't super cold. Very tall palms have better tolerance to cold here, so I think that when the palm grows away from it's heat source, that it would maybe be able to survive the cold. The pool will be salt water, so splashback won't hurt the palm, so it can be planted close to the pool.

I think it will work wonderfully then.

regards

Tyrone

[Zeeth]

Your idea sounds like it would work to me, but I'm not familiar with your area to know how cold you get. It also depends on how big the pool is (it's heat sink ability), it's aspect to the sun (as that would heat it up-if it's in shade it wouldn't get that warm) and whether you get advective freezes rather than radiational freezes and how far away the palm is from the pool. As it gets taller the crown will move away from the pool and away from the microclimate. In an advective freeze microclimates have less of a warming effect compared to radiational freezes.

My thoughts are that a normal sized pool in a radiational cooling situation may hold 3-4C or approx 5-8F over ambient temp. Add rocks and a rockery that's fully exposed to the winter sun and the extra thermal mass may hold more.

They're my thoughts for what it's worth.

Best regards

Tyrone

In the area we are moving to, the climate is humid subtropical, with USUALLY 1 freeze every year or 2 (this year saw 5 or 6) and temps USUALLY bottom out at 30 to 32F (-1 to 0C) when it does freeze (this years minimum was about 27F (-3C)). The pool would be in full sun. We normally get only radiational freezes, adjective freezes are more rare, and tend to keep frost at bay when they aren't super cold. Very tall palms have better tolerance to cold here, so I think that when the palm grows away from it's heat source, that it would maybe be able to survive the cold. The pool will be salt water, so splashback won't hurt the palm, so it can be planted close to the pool.

I think it will work wonderfully then.

regards

Tyrone

Thanks! Now I don't have to worry so much about us moving more inland (which is why I want to have a good way to protect the coconut), as I at least will have 1 coconut palm that will live through the worst of winters. My mom really likes the idea too, as it will be really cool looking

Keith

[Jeff in St Pete]

Hi Keith, a friend of mine who is somewhat of a coconut expert told me that Jamaican Talls tend to get a curve in the trunk even if they are planted out alone in full sun. He said the Pacific Talls tend to grow straight up with a straight trunk - unless they are planted in partial shade and are seeking the sun, then they will curve.

[Tampa Scott]

Keith, I have a heated pool (south facing) and yes it helps with a light freeze 30f-32f. When temps fall lower than 30f the steam freezes on the top of the screen on the pool cage and it will have a heavy frost coating. I have Ti plants and other tropical plants growing in pool planters that come thru with no damage. These plants are on avg. of 2-4' tall and enjoy the steambath,but 7-8' up its frosty. What side of the house will the pool be located?

[Zeeth]

Keith, I have a heated pool (south facing) and yes it helps with a light freeze 30f-32f. When temps fall lower than 30f the steam freezes on the top of the screen on the pool cage and it will have a heavy frost coating. I have Ti plants and other tropical plants growing in pool planters that come thru with no damage. These plants are on avg. of 2-4' tall and enjoy the steambath,but 7-8' up its frosty. What side of the house will the pool be located?

It will be facing south.

[Zeeth]

Hi Keith, a friend of mine who is somewhat of a coconut expert told me that Jamaican Talls tend to get a curve in the trunk even if they are planted out alone in full sun. He said the Pacific Talls tend to grow straight up with a straight trunk - unless they are planted in partial shade and are seeking the sun, then they will curve.

So you think it would be better to use one of my Jamaican talls?

[Tampa Scott]

Keith, Can the Coconut be planted on the S.E. side of the pool? It will be the warmest micro on the S.E. corner. I have a small Coconut planted on the S.E. side of the lake with 2 overhead S.roms that has come thru the last 2 winters with minor spotting only.

[Zeeth]

Keith, Can the Coconut be planted on the S.E. side of the pool? It will be the warmest micro on the S.E. corner. I have a small Coconut planted on the S.E. side of the lake with 2 overhead S.roms that has come thru the last 2 winters with minor spotting only.

It can be planted anywhere, that's why I'm asking questions now before the pool is actually planned, so we can plan for the spot of the coconut. Minor spotting and you fell to 27? That's great, as the low of the area we're moving to was also 27! Thanks for the tip about the SE side of the pool, any more tips?

Keith

[floridasun]

theres some in downtown melbourne that have no spotting at all, but just down the road there brown. most of them have one green frond at least. and weather.com said it got to 25! at melbourne intl. goes to show how you cant trust books that say you cant grow coconuts north of palm beach lol, heck i even saw a breadfuit tree! i dont know how its doing now though, there hardier than people think. so dont choose to not grow somthing that you havent tried yourself.

Edited March 1, 2010 by floridasun

[rozpalm]

My personal experience is that it will provide a microclimate for the first cold front of the season, and then as the pool water temps dive into the 50's, its not very effective. Below is a picture from Feb., about 4weeks after we had that horrific 10day cold front. My coldest temp in the yard was 32deg for 4hours. My house faces East/West and my pool holds about 37kgal. I did not see any frost, but I am guessing that I got some. The coco's near my pool fared no better then the ones further away. I imagine if I heated the pool, it would have done a better job. But, for what it would cost to keep the pool heated all winter, I could afford to replace all the coco's around the pool.

Edit: I should have also added that the lowest temp near my pool was 32.6 and warmest point in the yard was 34.7 which was near the lake. My coldest temp was 32.0 which was the lowest spot in the yard. Here is also picture of my Latania lontaroides with some burn. Thankfully it is recovering and growing again.

[floridasun]

WOW amazing pool thats weird thats exactly how alot look up here on the irl. the cocos i mean.

Edited March 1, 2010 by floridasun

[Zeeth]

My personal experience is that it will provide a microclimate for the first cold front of the season, and then as the pool water temps dive into the 50's, its not very effective. Below is a picture from Feb., about 4weeks after we had that horrific 10day cold front. My coldest temp in the yard was 32deg for 4hours. My house faces East/West and my pool holds about 37kgal. I did not see any frost, but I am guessing that I got some. The coco's near my pool fared no better then the ones further away. I imagine if I heated the pool, it would have done a better job. But, for what it would cost to keep the pool heated all winter, I could afford to replace all the coco's around the pool.

Edit: I should have also added that the lowest temp near my pool was 32.6 and warmest point in the yard was 34.7 which was near the lake. My coldest temp was 32.0 which was the lowest spot in the yard. Here is also picture of my Latania lontaroides with some burn. Thankfully it is recovering and growing again.

Hmm, interesting. I like the pool design. I wonder what the difference would be between heated and unheated. I think if you start heating it a day or 2 before a predicted frost, and turn the heat off after the event, more of a warming effect would be created with not too much cost. Of course, with 10 days of cold like Fl got this year, it would start to get expensive, but hopefully that doesn't happen again ever.

[Walt]

I submit there's just not enough thermal mass in the standard yard pool to offer much of a boost in nighttime low temperatures to be very meaningful. Yes, the laws of physics dictate that the area in proximity of the pool, all other things being equal, will be warmer, but not to the degree that would do much good in a freeze event. This is especially true of an advective event.

[JASON M]

Wait so if my family got a heated pool... in our 5B zone... that means we could grow all sorts of palm trees next to it? AWESOEM!

[Tampa Scott]

Here is the Coconut... Edited March 1, 2010 by Tampa Scott

[Zeeth]

I submit there's just not enough thermal mass in the standard yard pool to offer much of a boost in nighttime low temperatures to be very meaningful. Yes, the laws of physics dictate that the area in proximity of the pool, all other things being equal, will be warmer, but not to the degree that would do much good in a freeze event. This is especially true of an advective event.

Do you believe this to be true even for a heated pool? I know that an unheated pool will likely do nothing, but a heated pool may provide an advantage. One thing that gave me a hint that this may work is a yard close to mine. They have numerous coconuts in the yard, and all were fried in the freeze event but one. That particular one was under less canopy than some of the others, it wasn't any taller than any others, but one thing was that it is planted about 2 feet from a, probably heated, pool (separated by a screen, but 2 feet nonetheless). This coconut was almost undamaged by the freeze event.

[Zeeth]

Here is the Coconut...

Very nice, that one's a keeper!

[Tampa Scott]

Keith, I believe you will need to provide some type of overhead protection on the frosty/cold nights. I really do not think the pool generated heat is going to help without a covering on the palm. Here are the daily lows recordered on my weather station starting with 1/03/10 - 36,34,34,31,30,38,29,29,27,30,33,36 on 1/11/10 the temp stayed below freezing 11 hrs. I recorded 30 hrs below freezing this winter.

Edited March 2, 2010 by Tampa Scott

[Zeeth]

Keith, I believe you will need to provide some type of overhead protection on the frosty/cold nights. I really do not think the pool generated heat is going to help without a covering on the palm. Here are the daily lows recordered on my weather station starting with 1/03/10 - 36,34,34,31,30,38,29,29,27,30,33,36 on 1/11/10 the temp stayed below freezing 11 hrs. I recorded 30 hrs below freezing this winter.

Alright. I'm thinking about designing a portable pool screen design. It will be a lightweight collapsable box that I can slip over top of the crown that will act as a type of canopy, but it can be easily removed. Maybe with the 2 forms of protection, I'll be set.

[floridasun]

some in orlando were not badly damaged, particularly downtown- idrive, a few weeks ago i saw a baby coconut palm up against a low wall that was hardly damaged, if that wall creates eneogh heat then why wouldnt a even an unheated pool, hmm you could build a courtyard kind of thing, with a big wall surrounding the pool, then paint it with an ocean panorama. with palms of course.

Edited March 2, 2010 by floridasun

[Tyrone]

I think many are forgetting an important factor in growing coconuts. While the absolute min has an effect on the survivability of the coconut, maximum temps have more of an effect on a coconuts survivability during the cooler months. If you get down to 32F, but still get to 70-75F during the day, your coconut will not have many problems. But if you go down to to 32F or even 35F and not get to at least 65-70F during the day for a few days, your coconut will suffer. You may lose it. If you don't get above 50F for a week or two, your coconut is gone regardless of the minimums it experienced. Add rainfall and it's definitely all over at those temps.

In my experience if you only get light frost (ie 32F every now and again), a pool of average size and unheated will prevent any frost within about 30ft of the pool. You will have kept the surrounds maybe as high as 36,37F which is all it may take to keep things happy. When placing a coconut though, you want to keep it in an area where temps reliably hit 70F every day.

Best regards

Tyrone

[Zeeth]

I think many are forgetting an important factor in growing coconuts. While the absolute min has an effect on the survivability of the coconut, maximum temps have more of an effect on a coconuts survivability during the cooler months. If you get down to 32F, but still get to 70-75F during the day, your coconut will not have many problems. But if you go down to to 32F or even 35F and not get to at least 65-70F during the day for a few days, your coconut will suffer. You may lose it. If you don't get above 50F for a week or two, your coconut is gone regardless of the minimums it experienced. Add rainfall and it's definitely all over at those temps.

In my experience if you only get light frost (ie 32F every now and again), a pool of average size and unheated will prevent any frost within about 30ft of the pool. You will have kept the surrounds maybe as high as 36,37F which is all it may take to keep things happy. When placing a coconut though, you want to keep it in an area where temps reliably hit 70F every day.

Best regards

Tyrone

Where I am, the cool usually isn't what damages the coconuts (this was a freak year), it's the absolute minimum temp and frost. Normally things warm up pretty soon after a frost event.

[Walt]

I submit there's just not enough thermal mass in the standard yard pool to offer much of a boost in nighttime low temperatures to be very meaningful. Yes, the laws of physics dictate that the area in proximity of the pool, all other things being equal, will be warmer, but not to the degree that would do much good in a freeze event. This is especially true of an advective event.

Do you believe this to be true even for a heated pool? I know that an unheated pool will likely do nothing, but a heated pool may provide an advantage. One thing that gave me a hint that this may work is a yard close to mine. They have numerous coconuts in the yard, and all were fried in the freeze event but one. That particular one was under less canopy than some of the others, it wasn't any taller than any others, but one thing was that it is planted about 2 feet from a, probably heated, pool (separated by a screen, but 2 feet nonetheless). This coconut was almost undamaged by the freeze event.

My last reply was based on an unheated pool, which will continue to drop in temperature as the days get shorter (less solar radiation) and air temperatures drop.

A heated pool, say if it was maintained above 80 degrees F, might have some beneficial heating effect in proximity of it, and most likey over it. I wouldn't think it would be too much, though.

I'm not sure how one could calculate what the benefit might be. When I envision an in-ground pool, say maintained at 80 degrees F during the winter, I think of the heat transfer (loss) from the pool's water surface into the air above it. The colder the air, the faster the transfer. But just how many BTU's of heat/minute transfers out (to the air above it and earth around it), I have no idea. But in any event, the pool heater couldn't be a solar panel heater, as there wouldn't be any heat production at night. One would need a propane, natural gas, or electric pool heater. I know these heaters (depending on size) put out between 100K to 400K BTU. Maybe if a pool could release several hundred thousand BTU/hour it well could keep the immediate area around it a few degrees warmer

However, releasing that amount of BTU would be cost prohibitive IMO, if one had to do it on all the below 40 degree nights we had this past winter.

FYI, one pound of propane contains 21,669 BTU, but there are combustion losses/inefficiencies, so one pound isn't going to yeild it's total gross heat. What I'm trying to convey here is that if your pool heater fired at 400K BTU/hour, it would be burning more than 18 pounds of propane per hour. And most patio/outdoor grills use 20 pound propane tanks. So you would be going through the equivalent of almost one 20 pound propane tank per hour!

That's why I said it would be cost prohibitive.

[Zeeth]

I submit there's just not enough thermal mass in the standard yard pool to offer much of a boost in nighttime low temperatures to be very meaningful. Yes, the laws of physics dictate that the area in proximity of the pool, all other things being equal, will be warmer, but not to the degree that would do much good in a freeze event. This is especially true of an advective event.

Do you believe this to be true even for a heated pool? I know that an unheated pool will likely do nothing, but a heated pool may provide an advantage. One thing that gave me a hint that this may work is a yard close to mine. They have numerous coconuts in the yard, and all were fried in the freeze event but one. That particular one was under less canopy than some of the others, it wasn't any taller than any others, but one thing was that it is planted about 2 feet from a, probably heated, pool (separated by a screen, but 2 feet nonetheless). This coconut was almost undamaged by the freeze event.

My last reply was based on an unheated pool, which will continue to drop in temperature as the days get shorter (less solar radiation) and air temperatures drop.

A heated pool, say if it was maintained above 80 degrees F, might have some beneficial heating effect in proximity of it, and most likey over it. I wouldn't think it would be too much, though.

I'm not sure how one could calculate what the benefit might be. When I envision an in-ground pool, say maintained at 80 degrees F during the winter, I think of the heat transfer (loss) from the pool's water surface into the air above it. The colder the air, the faster the transfer. But just how many BTU's of heat/minute transfers out (to the air above it and earth around it), I have no idea. But in any event, the pool heater couldn't be a solar panel heater, as there wouldn't be any heat production at night. One would need a propane, natural gas, or electric pool heater. I know these heaters (depending on size) put out between 100K to 400K BTU. Maybe if a pool could release several hundred thousand BTU/hour it well could keep the immediate area around it a few degrees warmer

However, releasing that amount of BTU would be cost prohibitive IMO, if one had to do it on all the below 40 degree nights we had this past winter.

FYI, one pound of propane contains 21,669 BTU, but there are combustion losses/inefficiencies, so one pound isn't going to yeild it's total gross heat. What I'm trying to convey here is that if your pool heater fired at 400K BTU/hour, it would be burning more than 18 pounds of propane per hour. And most patio/outdoor grills use 20 pound propane tanks. So you would be going through the equivalent of almost one 20 pound propane tank per hour!

That's why I said it would be cost prohibitive.

Makes sense. I think that tests probably need to be done to see exactly what temp the pool would need to be at, how long, etc, but I think I'll have a backup plan just incase. I am pretty handy, so I think I can design a "portable canopy" that can be put on and removed without much hassle, and can be put on a fully grown palm with only a ladder to climb up with. I think I'll get some fiberglass screen and some lightweight material for the skeleton. Maybe bamboo? I'll start tinkering when the weather warms up and see what I can come up with.

[Xenon]

Just a theory, a pool would have enough stored heat to release it in the first radiational freeze,but during the time period between the first and second freeze, because of Florida's multitude of days in the 70s, wouldn't the pool have gained enough heat energy to release it again? This would probably work well in South FLorida, and the Tampa Bay area, as well as South Texas. Not Cali though.Of course this theory also wouldn't work if the temperature gradually plummeted.No 40s before the freeze. Just my two cents.

-Jonathan

Edited March 28, 2010 by Xenon

[Walt]

Just a theory, a pool would have enough stored heat to release it in the first radiational freeze,but during the time period between the first and second freeze, because of Florida's multitude of days in the 70s, wouldn't the pool have gained enough heat energy to release it again? This would probably work well in South FLorida, and the Tampa Bay area, as well as South Texas. Not Cali though.Of course this theory also wouldn't work if the temperature gradually plummeted.No 40s before the freeze. Just my two cents.

-Jonathan

A typical swimming pool just doesn't have the thermal mass -- as compared to the ocean/Gulf, large lake, etc. Therefore, the relative little heat it has to release isn't going to affect the surrounding area to any great degree.

Years ago I had a rectangular 10,000 gallon above ground pool. I had a double adonida palm in a 20 gallon pot placed right up against the south end of the pool (part of the canopy extending out over the water), figuring the relative warm water would keep frost off my adonidia palm leaves during radiational freeze, which make up about 95% of the freeze I get here in south central Florida. WRONG!

One night it dropped into the 20s and my leaves still got frost burned. While the pool surely helped some, it wasn't enough.

But logically, and from a physics stand point, this makes sense. My swimming pool typically dropped about five degrees at night, then warmed up five degrees during the day, provided the sun was full.

It takes one BTU of heat to raise the temperature of one pound of water one degree F. One gallon of water weighs 8.33 pounds. So, 10,000 gallons X 8.33 = 83,300 BTU of heat available for release during a typical winter night that falls into the upper 20sF.

83,300 BTU may sound like a lot, but then that is being radiated off over the entire external area of the pool, including the pool's bottom, as the ground is colder than the pool water. My pool was 13' X 25' X 4' deep. So when you calulate the surface (water) of the pool, all four sides, plus the pool floor, you can see there's not that much BTU (heat) being released at any one point.

If one calulates the total pool area (all four sides, floor, and water surface area), it comes out to 629 square feet. 83,300 divided by 629 SF = 132 BTU/ SF. If the pool released all the heat available in a five degree water temperature drop (which is typical over night), in one hour, the heat released would average 132 BTU/SF of pool area. But, the heat drop wouldn't happen in one hour, but over the course of the entire night. So as you can clearly see, there really isn't enough heat available at any one point around a swimming pool to make much of a difference.

And to relate to how much 132 BTU is, air conditioning/heating engineers generally use about 350 BTU/hour as the amount of heat an average person gives off per hour (say when sitting around in their house).

The bottom line for me is, yes, an inground swimming pool surrounded by a concrete deck (that absorbs sun heat) will surely be better than plain ole ground, but it's not going to be as effective as one might think.

[Trópico]

This is why you should hug your palm trees often, more so during cold nights

[Xenon]

This is why you should hug your palm trees often, more so during cold nights

LOL!

[Alicehunter2000]

Just a theory, a pool would have enough stored heat to release it in the first radiational freeze,but during the time period between the first and second freeze, because of Florida's multitude of days in the 70s, wouldn't the pool have gained enough heat energy to release it again? This would probably work well in South FLorida, and the Tampa Bay area, as well as South Texas. Not Cali though.Of course this theory also wouldn't work if the temperature gradually plummeted.No 40s before the freeze. Just my two cents.

-Jonathan

A typical swimming pool just doesn't have the thermal mass -- as compared to the ocean/Gulf, large lake, etc. Therefore, the relative little heat it has to release isn't going to affect the surrounding area to any great degree.

Years ago I had a rectangular 10,000 gallon above ground pool. I had a double adonida palm in a 20 gallon pot placed right up against the south end of the pool (part of the canopy extending out over the water), figuring the relative warm water would keep frost off my adonidia palm leaves during radiational freeze, which make up about 95% of the freeze I get here in south central Florida. WRONG!

One night it dropped into the 20s and my leaves still got frost burned. While the pool surely helped some, it wasn't enough.

But logically, and from a physics stand point, this makes sense. My swimming pool typically dropped about five degrees at night, then warmed up five degrees during the day, provided the sun was full.

It takes one BTU of heat to raise the temperature of one pound of water one degree F. One gallon of water weighs 8.33 pounds. So, 10,000 gallons X 8.33 = 83,300 BTU of heat available for release during a typical winter night that falls into the upper 20sF.

83,300 BTU may sound like a lot, but then that is being radiated off over the entire external area of the pool, including the pool's bottom, as the ground is colder than the pool water. My pool was 13' X 25' X 4' deep. So when you calulate the surface (water) of the pool, all four sides, plus the pool floor, you can see there's not that much BTU (heat) being released at any one point.

If one calulates the total pool area (all four sides, floor, and water surface area), it comes out to 629 square feet. 83,300 divided by 629 SF = 132 BTU/ SF. If the pool released all the heat available in a five degree water temperature drop (which is typical over night), in one hour, the heat released would average 132 BTU/SF of pool area. But, the heat drop wouldn't happen in one hour, but over the course of the entire night. So as you can clearly see, there really isn't enough heat available at any one point around a swimming pool to make much of a difference.

And to relate to how much 132 BTU is, air conditioning/heating engineers generally use about 350 BTU/hour as the amount of heat an average person gives off per hour (say when sitting around in their house).

The bottom line for me is, yes, an inground swimming pool surrounded by a concrete deck (that absorbs sun heat) will surely be better than plain ole ground, but it's not going to be as effective as one might think.

Geez Wal....a simple yes or no would have worked

Well I guess this figures into my design plans for my new house as well. I plan on having a courtyard pool design with all sides being surounded by a heated home, heated pool and overhead screen and good sun position. I plan on this bumping me up a zone ..... but I don't think I can expect to grow coconuts....maybe just some 9b stuff.

[Xenon]

Just a theory, a pool would have enough stored heat to release it in the first radiational freeze,but during the time period between the first and second freeze, because of Florida's multitude of days in the 70s, wouldn't the pool have gained enough heat energy to release it again? This would probably work well in South FLorida, and the Tampa Bay area, as well as South Texas. Not Cali though.Of course this theory also wouldn't work if the temperature gradually plummeted.No 40s before the freeze. Just my two cents.

-Jonathan

A typical swimming pool just doesn't have the thermal mass -- as compared to the ocean/Gulf, large lake, etc. Therefore, the relative little heat it has to release isn't going to affect the surrounding area to any great degree.

Years ago I had a rectangular 10,000 gallon above ground pool. I had a double adonida palm in a 20 gallon pot placed right up against the south end of the pool (part of the canopy extending out over the water), figuring the relative warm water would keep frost off my adonidia palm leaves during radiational freeze, which make up about 95% of the freeze I get here in south central Florida. WRONG!

One night it dropped into the 20s and my leaves still got frost burned. While the pool surely helped some, it wasn't enough.

But logically, and from a physics stand point, this makes sense. My swimming pool typically dropped about five degrees at night, then warmed up five degrees during the day, provided the sun was full.

It takes one BTU of heat to raise the temperature of one pound of water one degree F. One gallon of water weighs 8.33 pounds. So, 10,000 gallons X 8.33 = 83,300 BTU of heat available for release during a typical winter night that falls into the upper 20sF.

83,300 BTU may sound like a lot, but then that is being radiated off over the entire external area of the pool, including the pool's bottom, as the ground is colder than the pool water. My pool was 13' X 25' X 4' deep. So when you calulate the surface (water) of the pool, all four sides, plus the pool floor, you can see there's not that much BTU (heat) being released at any one point.

If one calulates the total pool area (all four sides, floor, and water surface area), it comes out to 629 square feet. 83,300 divided by 629 SF = 132 BTU/ SF. If the pool released all the heat available in a five degree water temperature drop (which is typical over night), in one hour, the heat released would average 132 BTU/SF of pool area. But, the heat drop wouldn't happen in one hour, but over the course of the entire night. So as you can clearly see, there really isn't enough heat available at any one point around a swimming pool to make much of a difference.

And to relate to how much 132 BTU is, air conditioning/heating engineers generally use about 350 BTU/hour as the amount of heat an average person gives off per hour (say when sitting around in their house).

The bottom line for me is, yes, an inground swimming pool surrounded by a concrete deck (that absorbs sun heat) will surely be better than plain ole ground, but it's not going to be as effective as one might think.

Umm..very good explanation..but I don't understand a lot of it..cause I'm only twelve.

-Jonathan

[amazondk]

I think many are forgetting an important factor in growing coconuts. While the absolute min has an effect on the survivability of the coconut, maximum temps have more of an effect on a coconuts survivability during the cooler months. If you get down to 32F, but still get to 70-75F during the day, your coconut will not have many problems. But if you go down to to 32F or even 35F and not get to at least 65-70F during the day for a few days, your coconut will suffer. You may lose it. If you don't get above 50F for a week or two, your coconut is gone regardless of the minimums it experienced. Add rainfall and it's definitely all over at those temps.

In my experience if you only get light frost (ie 32F every now and again), a pool of average size and unheated will prevent any frost within about 30ft of the pool. You will have kept the surrounds maybe as high as 36,37F which is all it may take to keep things happy. When placing a coconut though, you want to keep it in an area where temps reliably hit 70F every day.

Best regards

Tyrone

Where I am, the cool usually isn't what damages the coconuts (this was a freak year), it's the absolute minimum temp and frost. Normally things warm up pretty soon after a frost event.

Keith,

There is no way yet do tell if this year was a freak event. It could turn out to be the norm for years ahead. There is no way to know this. And, some say this is exactly what is going to happen. Time will tell.

dk

[Erik]

Sorry to jump in two weeks late.

I plants my palms (in Zone 7!) around my pool. My wife and I debate endlessly about heating it, and never have ($$$).

The extra variable I didn't see mentioned above was wind. Sure, like everyone else our absolute lowest temps are on windless nights, but we get pretty darn cold on windy nights, too, which just makes it seem like tossing dollar bills into the breeze with respect to palm protection. --Terdal Farm

[Tyrone]

i think if you're just marginal for a particular species, a pool will maybe get it through the winter. But if you're a few zones out a pool will do little. Yes, wind events will totally undo any heating from the pool. In my virtually frost free climate, a pool will likely prevent all frost, and our cold events are always radiational with no wind. If I had a pool I still wouldn't be able to grow a lipstick palm.

Best regards

Tyrone

[Erik]

Tyrone, so true.

Up here (36oN) my pool-side palms are European fan palm, Brahea, Sabal, Trachy, Butia and the like! --Terdal Farm