Help Me Heat My Pool!

Factual Questions
1

We have a medium sized inground pool, and every spring I think about heating it somehow, but never get around to it. The kids survive in the frigid waters from Memorial Day to Labor Day or so, but I’d like to kick it up a bit to a)extend the season some, and b) make it tolerable for me. I’m a wuss.

Even if I got a gas heater for free, the gas bill alone would be hundreds per month.
Solar is the way to go, but commercial panels are pricey. I’ve seen home-made hose-on-panel projects, but I don’t think that will do what I want.

In researching this week I found a company that makes a heat exchangerthat sits in your attic. Pump water to it, take the heat from the attic, and back to the pool! Genius! But expensive!

I’ve settled on two thoughts, but need some Dopers mad math skills.
I could make a heat exchanger with an old radiator and a fan for just a few bucks, not the thousands for the commercial one. But -** will it work**? Just looking at the size of theirs, a big radiator from a truck is much bigger, and bigger is better, right?

The other idea is simply put some hose or pipe in the attic and run water through it.
I’m thinking 1/2 inch ID by about 1,000 feet to start. Black poly hose is less than 90 bucks for the 1,000 feet. Sure copper or black iron pipe may transfer and hold heat better, but the cost is too great.

Specs for the math kids: Pool is 15,000 gallons, vinyl liner, in-ground. Hot summer days bring it to about 80-82 degrees Farenheit, cooling at night. A few cloudy or rainy days will drop it to 70 or so.
Attic is typically 130 to 140 degrees Farenheit during the summer.

The heat is up there. I need to know how many feet of hose or pipe I need to draw enough to make it worthwhile.

OK, you thermodynamic geniuses - think of my dear, blue cheerins and give me the Straight Dope on heat transfer!

2

try these. cheap and easy, and they really do work. Provided you have sun…

3

A solar cover (looks like high-quality bubble wrap) works well to keep the heat in at night. The clear ones heat the pool best when the sun is out. You can buy a size slightly larger than your pool and trim to fit with scissors.

There’s a forum dedicated to pools I found very helpful, Trouble Free Pool. There have been several posts over the years about options for heating. Head over and search the archive.

4

Seconded! We have been using a “solar blanket” for the last 12 years. While our neighbors have a slightly longer pool season with the built-in solar roof panels, we get plenty of pool time, the blanket costs less than $200, can be trimmed as stated for fit, and lasts about 3 years before it starts to deteriorate. We have been using the blue colored ones and they work great. Only downside is it usually takes a couple of people to neatly fold and roll up and remove from the pool. It works for both heating and retaining warmth. We usually dont need it at all by mid-summer (interior Northern CA).

I looked at the discs and thought they may be easier in that one person could remove them, but the downsides were the cost, and I heard you cannot stack them, so what are you supposed to do with 9 or 10 of them when your pool is in use? Hang them on the fence?

Also, IANA plummer, but I would not want to run water pipes thru my attic - what if you got a leak - think of the expensive repairs to your ceilings, etc.

5

My thoughts exactly, and I doubt your homeowner’s insurance is going to cover it unless it is commercial system installed by a plumber.

6

When I read the thread title, I thought you were going to ask for money to heat your pool because your bunny rabbits liked warm water.

7

No, no, no, don’t pump pool water into your attic, that just has bad idea written all over it.
Some friends of my parents kept their pool mechanicals in their basement and ended up flooding their basement when something leaked…now imagined that flooding your entire house.

If you’re willing to spend the money on that, why not just spend the money on a proper electric or gas fired pool heater?

8

That’s what happens when you give them air conditioning. Little guys get so cold they need a hot tub.

9

We’ve had pool blankets before. They’re a huge PITA for the heat they provide.

If I put hose in the attic, it will be on a spool and contained in a tub with an alarm and pump, so I’m not too worried about a leak.

I’ll check out that forum while I wait for the mathletes to check in…:smiley:

10

That will never work.
You need AREA for good heat exchange - having everything in a little tub is not going to allow you to transfer enough heat. Either go with a solar collector, or do something like reject your A/C’s waste heat into the pool (even that might not be enough heat, but it sure would increase it’s efficiency)…

11

It won’t cost hundreds unless you run it a lot.

How many months will you really need to run it? Where do you live? By July, we don’t need the heater. Heck, by Mid-June it won’t be used. Maybe now and then, when a cool evening takes some degrees away.

For all the entertainment you can add for the dollar, a pool heater is not expensive.

It doesn’t run from April to October.

Most people will use it a few times in May, a little in June, rarely in July and August, and maybe a couple o’ times in September.

A pool heater is the most exaggerated luxury item. Heck, take it over the movies or being stuck in traffic for a ball game.

NE USA (Delaware)

12

Have you considered getting a reel for the solar blanket? We have one on wheels. One person can easily crank the cover by themselves and roll it to the side of the pool within minutes.

13

A 25,000 gallon apartment building pool in the Seattle area spent no more than $600/month heating a pool to 78 F, circa 2005, via natural gas. The annual cost was about $2500/year, though, so you can see that most of the expense came in just a couple of months (May and September, mostly). We didn’t heat at all during October-April and it hovered around 45 F those months. We did cover it up at night.

I consider 78 to be ridiculously warm for swimming, but I understanding some people are working from an assumption that 80 or 82 is better. If it was my pool, I’d probably settle for anything in the 70’s and save a bundle of money doing that.

Covering a pool isn’t really that much work, especially if you tell yourself that you’re saving $1,000 a year in heating. (That’s an estimate, but I think it’s probably close enough.) Covering the pool also helps to keep your chemicals in, reducing costs for things like chlorination.

14

Couldn’t you make your own version of those pool disks? A box of black plastic garbage bags, and some hula-hoops. Cut open a bag, duct-tape it across the hoop, trim the excess plastic, and lay it in the pool. You could try it out for maybe 10 dollars for a few, and see if it seems like it would help.

15

The attic idea isn’t going to work unless you have huge heat exchange fins on metal pipes.

Do the black PVC on the roof thing or other method of getting heat directly from the sun. Solar blankets are a good idea, and nothing is a PITA when you have kids you can make do all the work. It’s mostly for them, let them cover and uncover every day.

16

I would go for black PVC tubing laid on the roof on the sunny side of the house. If it leaks, you don’t flood the house, and you get way more surface area to play with. It will cool your attic space and heat your pool.

Si

17

The plastic pipes on the roof are a very tried and developed way of heating. They are not are trouble free, but close to it. They develop small leaks over time, and need some maintenance. On a sunny they can have prodigious heat output. We regularly have the pool become too hot to use if the controller is not set right. A downside is that on very hot days you probably will turn the heater off, and then you end up with a black roof heating up.

I never liked pool blankets. One thing I dislike is that they accumulate leaves and dirt on top, and if you are not careful you deposit at least some of this in the pool when you take the blanket off. They eventually fail in the sun. No matter how much UV stabiliser is put in the material, eventually they go brittle. But value for money they are hard to beat.

I am somewhat impressed by the attic heater. If you have a suitable roof it looks a really good idea. The numbers look credible, and it could get close to an on-roof system for many people.

The problem with a truck radiator is multifold. A new one won’t be cheap. I doubt it will be any cheaper than buying the in-attic version once everything is sorted out. This is for two reasons. You can’t use an aluminium cored radiator. The pool water will kiil it in months. So you need a copper cored radiator. Like the in-attic one. You don’t want a second hand radiator. The reason it is second hand is it has failed at some point. Automotive radiators are soldered/brazed, and this is going to be subject to attack from the pool water too. The in-attic design is a single long copper pipe. I’m sure they are charging a premium whilst their patent holds, but you are probably also paying for both proper engineering and their liability insurance.

18

Never mind the attic. Buy some industrial water hose, paint it black (or if it comes in black, all the better). Attach it to a sheet of plywood, also painted black. The more hose you can get on the plywood, the better. Cover this with a sheet of plexiglass (or some affordable variant.) Now tie this unit into your circulating pump.

It’s not going to add ten degrees to your pool, but it’ll take the chill off, and regain you a few degrees from those chilly nights. Had a friend do this in upstate NY and it provides plenty of bang for the few bucks it costs.

19

The cheapest, and safest from water damage, but not pretty, solution would probably be some black plastic piping up on the roof. I’ve used this to heat water from a hose, not for a pool. You can pick up quite a bit of heat in direct sun and plastic pipes are pretty cheap - something like 100 ft for $25 of 1 inch diameter and $12 for 1/2 inch. I would recommend setting up some way to easily bypass the roof loop just in case - you may not need to put valves in, but just have the parts needed to cut out the loop if need be.

With the plastic adapters running at about $1 each you may be able to put this into action for under $30 or even $17 with the smaller pipes. Pretty cheap to try, now if it works well making it look nice will be another story.

20

Where do the leaves and dirt go if you don’t use a pool blanket?