2-speed pump recommendation for sand filter/etc? ... solar makers says 'not so fast'

[99ways2die]

Hi guys,
1st, like many others, a big thank you for everyone for the invaluable education from the TFP. Thanks to everything I've learned here i seldom visit any and all pool stores, and when i do, i sometimes end up handing out slips of paper with TFP site links to some of the poor souls in line with me.
...... ...not kidding.

Anyway,
Need some advice:
20by40, 30K vinyl in-ground (1 main, 1 skimmer, 2 returns, with a S270T Hayward sand filter, running on 1HP (full rating) pump. Pump/etc is 3ft away from pool.
I want to add solar panels in the near future (ground level mounted and about 10 -15 feet away from the pump/etc). Rough calcs call for 600-700 sq.feet coverage. I'd like to change the 1HP motor on the pump to a 2-speed motor as well.

I have the following Qs:
1. Is a 2-speed pump/motor a 'no-no' for solar applications and SAND filters?
(according to a well received solar manufacturer (even here) a sand filter and a 2-speed are no-go..........I can't see a reason why; he claims too much pressure loss)
2. If going with 2-speed, is 1HP(true rating) enough or should i step up to 1.5HP?

Thanks for any and all insight.
-99

 

[woodyp]

My 1 hp 2 speed moves as many gpm as my old 1.5 hp single speed did. And I have the 2 speed option! The business with the sand filter is junk science. Works fine.

 

[mas985]

I think what they mean is that in most cases, you will not be able to run solar on low speed. But that doesn't mean a two speed is a bad idea. It only means that when running solar, you will need to run on high speed. But other times you can run on low speed. That is what I do.

Also, I have a 1/2 HP for my solar so I would not worry about having a 1 HP although it does depend on the pump model (i.e. head curve). Just saying 1 HP does not really describe a pump. Model # is important.

 

[jblizzle]

Yup, I only run mine on high for solar ... in fact the last week or so, the pool has reached the set temp and the automation automatically turns off the solar and puts the pump down to low speed saving me $$$

- - - Updated - - -

Are you aware of the print yourself business cards:
http://www.troublefreepool.com/threads/71205-TFP-Business-Cards

Or the ones Dave will send you?
http://www.troublefreepool.com/threads/74867-TFP-Business-Cards

 

[99ways2die]

I didn't want to sound "know it all" so i didn't pursue the subject at the time, but the comment was about 2-speed not being a choice "because you have a sand filter anyway...and it won't work."

Understand that I need to run it on high speed for solar.............now all I need so someone to convince my wife that spending the $ on panels and automation is a "great idea."



PS:
I'm affraid of a beat down with those cards in hand!

 

[mas985]

Sorry misunderstood. It is true that small sand filters have a lot of pressure loss but proper placement of the VRV can usually mitigate that issue.

As to automation, the solar only controllers are bit cheaper.

http://www.amazon.com/Goldline-Automatic-Solar-Heater-Controller/dp/B002WKM2ES

 

[99ways2die]

Is S270T sand filter considered "small"? Color me surprised then.

All in all-can i run this set up (1HP 2-speed with S270T and solar) in the following manner?
1. When in filtering-only mode we run on low speed; solar valves closed off.
2. When solar wants to come to life (via the above mentioned controller or similar) then it will switch the pump over to high speed and run at that as long as the solar is in action.

...or should i just shrink my kids and buy a large magnifying glass?

 

[Isaac-1]

My only thought is you may want to go up to a 1.5 HP 2 speed pump with that many panels to get a reasonable flow rate. I have 11 4x12 (528 sq ft)panels mounted on a roof about 12-15 feet above my pump, and get only a little over 40GPM through them with the pump on high (or about 3.6 GPM per panel, optimal flow would be about 4.3 GPM per panel), however I do have a Hayward Perflex DE filter which tends to have a good bit of back pressure.

 

[mas985]

It all depends on the model pump and the plumbing. I have a 1/2 HP pump and I get about 55 GPM through my panels so I end up bypassing some flow.

All in all-can i run this set up (1HP 2-speed with S270T and solar) in the following manner?
1. When in filtering-only mode we run on low speed; solar valves closed off.
2. When solar wants to come to life (via the above mentioned controller or similar) then it will switch the pump over to high speed and run at that as long as the solar is in action.

You should. What is the model # of your pump?