Free Pool Cleaner - New Applications.

[AllanB]

I thought of continuing the old "free pool cleaner" thread, but it got so polluted, that real people have probably lost interest and won't read this. There are a few people who had shown interest and a couple who are actually building one, so this thread is for you.

As you know I have a roof on my pool and it is very successful, perhaps too successful when it comes to keeping the water cool. Over the last 2 days the water temperature has dropped to 24c, due to the unusually cold nights we have had in Isaan, so I have been thinking about a heater, or rather my family have been telling me they want a heater.

Bubble-wrap isn't going to work because of the roof, so the obvious way to do this is to pump the pool water through a simple heat exchanger, like black plastic tubing and having a roof makes that easy. I just chuck it up on the roof. But then I had to plumb it into my pumping circuit, which is a pain, then while using my "free pool cleaner" I thought "use that pump instead".

So I simply throw black plastic tubing up on the flat steel roof, connect one end to the pool cleaner's submersible pump and drop it into the pool. I hang my 1 micron bag filter from the underside of the roof and put the other end of the heat exchanging hose into the bag and that has 4 functions.

1. It picks up solar heat, plus heat from the roof itself.

2. It polishes the water by filtering it down to 1 micron.

3. It aerates the water as this creates a waterfall, slightly raising the PH, which is currently a little low.

4. If I put a chlorine tablet in the bag filter, it chlorinates the water at the same time.

I haven't done this yet, so will have to experiment with the correct length of pipe to get the gain I want, but the lower flow of the submersible pump will be more efficient than using the 1hp main pump, so I can run it for longer and gain more heat.

This is not quite a free solution, but pretty dam_n cheap and when the weather gets warmer it is very easy to dismantle and stow away. I can then enjoy the cooler water the roof has afforded me, along with the use of the pool all day long.

One thing I am minded of is "scalding" when the system is off and upon start up and will have to address that.

Meanwhile the pool water is still pristine, though a little chilly, I will keep you posted, but if anyone has done the plastic tubing thing and will share some figures with me, it would be helpful.

[kriswillems]

Plastic is a very bad heat conductor. You might need copper tubes and you need to make sure they make a very good thermal contact with the metal roof. This will not be cheap.

[necronx99]

Plastic is not the best conductor, but solar pool arrays are large, huge even.

Commercial solar pool heaters do use plastic, but you need a crapload of it.

What you need to consider is the required flowrate at a given temperature to warm your pool volume, how long it takes water to reach that temp in your pipe and how much pipe

you need to give the water time to get to that temp.

Solar power panel for your pump also so its not drawing mains all day..

[Naam]

i wonder what it takes that only people who have at least 20 years of experience heating their pool(s) with solar power render advice.

[AllanB]

Plastic is a very bad heat conductor. You might need copper tubes and you need to make sure they make a very good thermal contact with the metal roof. This will not be cheap.

I think that is not altogether true, it is basically a "black body" and very good at absorbing solar heat. Black plastic is what they make solar showers from and even in the Med they get pretty hot on a sunny day. Copper is completely impractical and as you say would cost a fortune. My problem is not heating the water, it is keeping the output temperature down without the pump running all day. The answer may be to use a very small pump and run it all day, they are pretty cheap to buy and run.

Solar powered pumps don't make any economic sense for this short-term application.

We are not looking to make tea here, just raising the temperature a few degrees and with the weather getting hotter now, I may leave this on the back burner until November. Pardon the pun.

[Naam]

good job Allan! i was too lazy to throw pearls...

[katabeachbum]

Plastic is a very bad heat conductor. You might need copper tubes and you need to make sure they make a very good thermal contact with the metal roof. This will not be cheap.

I think that is not altogether true, it is basically a "black body" and very good at absorbing solar heat. Black plastic is what they make solar showers from and even in the Med they get pretty hot on a sunny day. Copper is completely impractical and as you say would cost a fortune. My problem is not heating the water, it is keeping the output temperature down without the pump running all day. The answer may be to use a very small pump and run it all day, they are pretty cheap to buy and run.

Solar powered pumps don't make any economic sense for this short-term application.

We are not looking to make tea here, just raising the temperature a few degrees and with the weather getting hotter now, I may leave this on the back burner until November. Pardon the pun.

why not have a pool water thermostat control the pump?

you might find it more efficient with a LPG burner tho

and I fail to see how this provides a free pool cleaner

[AllanB]

Plastic is a very bad heat conductor. You might need copper tubes and you need to make sure they make a very good thermal contact with the metal roof. This will not be cheap.

I think that is not altogether true, it is basically a "black body" and very good at absorbing solar heat. Black plastic is what they make solar showers from and even in the Med they get pretty hot on a sunny day. Copper is completely impractical and as you say would cost a fortune. My problem is not heating the water, it is keeping the output temperature down without the pump running all day. The answer may be to use a very small pump and run it all day, they are pretty cheap to buy and run.

Solar powered pumps don't make any economic sense for this short-term application.

We are not looking to make tea here, just raising the temperature a few degrees and with the weather getting hotter now, I may leave this on the back burner until November. Pardon the pun.

why not have a pool water thermostat control the pump?

you might find it more efficient with a LPG burner tho

and I fail to see how this provides a free pool cleaner

The free pool cleaner was from a previous thread, see below, I was extending the use of my "free" pool cleaner...

A pool stat costs money, lots of wiring and other work and so does using LPG, this is all about very cheap or free and easy. Like chucking a few metres of plastic up on the roof, job done.