help needed with my diy solar pipe heating

[mother shipton]

Newbie member in New Zealand who is looking for some advice on a solar pool heater setup as Im just trying to utilize some roof space that I have.
iv lots of questions so I'll start with the basics,

setup:
40000 litre concrete inground pool
Sand filter
1.5 hp pump
Pool pipe 40mm pvc
New Solar pipe 15mm
mild winters with no frost

As my pool PVC pipe is 40mm i guess i can only have a max of 3x 15mm loops?
how long can my runs be if i have a 1.5hp pump?

The loops would be on top of my pumphouse roof above which i think would take 280m of 15mm pipe,
so 3x 93m runs or 4x70m runs would be better?

i do have another much larger roof which is 15m away but it would be 30m of to/from of pipe run in a garage roof space before the actual solar pipe starts to see sun.

 

[mas985]

As my pool PVC pipe is 40mm i guess i can only have a max of 3x 15mm loops?

No, you can have more loops. There is no fundamental limitation. In fact, it would be better to have more parallel loops for solar to reduce head loss.

At a bare minimum, you would want to match pipe cross sectional area, not diameter, so the number of loops should be greater than 40^2 / 15^2 or at least 8 loops but again, more loops would be better.

how long can my runs be if i have a 1.5hp pump?

Knowledge of only the pump HP is not enough to determine the length of the runs. What is the pump make and model?

But it general, the pump is probably not going to be a limiting factor.

The loops would be on top of my pumphouse roof above which i think would take 280m of 15mm pipe,
so 3x 93m runs or 4x70m runs would be better?

I would go with at least 10 loops but more would be better.

i do have another much larger roof which is 15m away but it would be 30m of to/from of pipe run in a garage roof space before the actual solar pipe starts to see sun.

The more panel capture area, the more heat transfer. It is your choice.

 

[mother shipton]

Knowledge of only the pump HP is not enough to determine the length of the runs. What is the pump make and model?

But it general, the pump is probably not going to be a limiting factor.

 

[mother shipton]

I would go with at least 10 loops but more would be better.

so what type of manifolds are you guys using to do this as my diy PVC would be 2m long to do this?

 

[mas985]

The manifolds are typically the same size as the supply and return pipes for the solar so 40mm. Pretty much like you have in the pictures. Just more loops.

But 280m of 15mm tubing is not a lot of solar capture area (~4m^2). You may only get about 0.5C temp rise.

As for the pump, 12.8m is a fairly low head pump but as long as the solar lift is less than half that, it should be ok.