Figuring Flow Rate

[mas985]

Assuming you have the 1 1/2 HP Optiflo pump, flow rate on typical AG plumbing is 50 GPM on high which means it would be about 25 GPM on low speed. So marginal. But a heater's operation is dictated not on flow rate but on pressure. If the pressure is too low, the heater will not kick on but because you have an AG pool, the pressure should be fine on low speed.

If you want more than guess, I would need a picture of your equipment setup and also the filter pressure on high speed.

[GaryT]

Get a 40 - 60gal barrel and backwash into it for 1 minute.
Volume will give you your flow rate

[mas985]

Backwash flow rates can be significantly higher than normal flow rates because backwash mode bypasses most of the return side plumbing so that method will not be very accurate.

[bottomcat]

But a heater's operation is dictated not on flow rate but on pressure.

@mas985: Thanks for replying. The reason I said the heater required a minimum flow is because the Service and Installation Manual specifies minimum flow on page 26 here: https://www.hayward-pool.com/pdf/man...stallation.pdf

If you want more than guess, I would need a picture of your equipment setup and also the filter pressure on high speed.

The pressure on high is 15 psi. I'll send pictures tomorrow.

Thanks!

[nefretrameses]

You can put a flow meter in your system. Try www.bestbuypoolsupply.com. Look under "in ground solar parts" and scroll down to the bottom of the page. About $60.00. Mark may want to comment about their accuracy.

[bottomcat]

'rameses, I considered getting one. I might use Gary's trick, but just disconnect the return line to fill the bucket.

[mas985]

Any modification to the return side plumbing will have a dramatic affect on the flow rate so again, would not be very accurate.

[bottomcat]

Okay, I'll drop that idea. I suppose the resistance of the return fitting would change the flow rate.

[bottomcat]

If you want more than guess, I would need a picture of your equipment setup and also the filter pressure on high speed.

Mark, here are the pictures (I think… never done this before):

[mas985]

I figure somewhere around 60 GPM on high speed and 30 GPM on low speed. But, adding a heater will add head loss and will reduce flow rate. If I add the head loss of a typical heater, it would drop the flow rate down to about 56 GPM on high and 28 GPM on low. So it should still be ok but it will depend on the heater head loss which isn't always published.