Figuring Flow Rate

[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.

[bottomcat]

Thanks Mark. I just read a little more of the installation manual. Nothing there about head loss, but the heater is adjustable for pressure, so I'm hoping I'll be OK. Also I noticed there is a paragraph about two-speed pumps:

"TWO-SPEED PUMP:
In a few cases the pressure from a two-speed pump is below the 1- pound minimum required to operate the water pressure switch on the heater. This is apparent when the pressure switch cannot be further adjusted. In these cases the pump must be run at high speed to operate the heater. If the pump and piping arrangement are such that the required 1-pound minimum pressure cannot be obtained, do not attempt to operate the heater. Correct the installation."

I assume by "pound" they mean "PSI" so given that I am at 4 psi on low, I should be OK I guess.

Thank you again to all for your help! Pool Forum is a great resource!