DIY Solar heater

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D

Dunkgrease

0
Aug 29, 2018
3
Portugal, Algarve
Hi, I created a pool heater by coiling 500 meters of 18mm in diameter on my flat roof, which is about 3.5m above the pool pump. I teed off from after the filter but before the return valve to the pool and the return from the heater loop comes back in before the pool pump. the pool pump is a fixed speed ESP, Silen 75 rated at 50-300 litres per minute and power of 1 to 1.2 kW

Normally (without the heater) the filter pressure indicator when clean is about 0.7 Bar. To get the flow through the heater loop I have to partly close the pool return valve in order to increase the pressure enough to overcome the "head" up to the roof. This means that the pressure indicator on the filter is up around 1 bar.

This is obviously putting a greater load on the pump and requiring more electricity.

When running the heater raises the temperature of my pool by 3 or 4 degrees C which is fine.

However I am concerned about the extra load on the pump and if that may reduce its life as well as the extra electricity costs.

I am wondering whether I would be better to install a dedicated small bore pump for the heater?

Would be interested to hear of your views on the subject.

thanks

Steve
 
:wave: Welcome to TFP!!!

Can you better explain the plumbing or add pictures?
Is all 500m in a single loop or did you split it up?

My firm belief is that the DIY solar heaters like you have made are not doing nearly as much to heat a pool as you may think. Solar heating is all about high flow rates through a large area exposure to the sun. So going with a smaller pump will just lower the little amount of heat your coil is adding. To achieve higher flow rates and more heat, you need many smaller pipes in parallel.

You only have 9 square meters (97 sqft), so that is a fairly good size compared to most DIY setups I see posted here.
 
I have added a schematic showing the layout. The heating pipe is 500m in total and is one continuous length. Pool volume is 29,000 litres and area 8m x 3m.

To answer an earlier question about the return. I did this as I thought it needed to come back in at the low pressure side of the pump and be mixed with the water coming from the pool. Happy to take advice though.

I have tried it under similar conditions with and without the heater and it does make a 3 degree difference.

Hope this helps.Pool heater piping layout.jpg
 
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