Hw long to run pump

[dalehileman]

I live in the Mojave Desert having a 35 gal conventional pool with sand filter presently using 1750-w 1-hp pump soon to replace with vf hoping significantly reduced electricity bill

My sweep uses a separate booster

At its slowest the new pump consumes 200 w. (1) Given my pool size, location, etc for how many hours a day should I supposedly run it

(2) Though Bill's Pool & Spa recommends I run my 1-hp pump 8 hrs/day I've instead set it to 3 hrs/day with perfectly satisfactory results. If this fact figures into the calculation, then taking into account that it won't be loaded by the sweep what would you estimate as the shortest period I might run the new 200-w pump

Thanks most kindly for considering my query

[lbridges]

Dale, if you do get a VF, keep in mind that running at slower speeds saves money (its not linear) - by that I mean 3 hours at a flow rate of 50 GPM costs more than 15 hours at 10 GPM although both move the same amount of water.

The rule of thumb is 1+ turn over of water, regardless of the pump flow rate. If you set the VF at 24GPM and run 24 hours a day that gives a turn over of 35,000 gallons, and at 24GPM the electricity use should be minimal.

[dalehileman]

Dale, if you do get a VF,

In fact it's out in the garage at this very moment

....keep in mind that running at slower speeds saves money (its not linear)....

Yes, very nonlinear, in fact that's why we acquired it, just waiting there till our good and dear buddy Mack Torque who is vastly more proficient at matters mechanical and pneumatic than I comes to visit

One misgiving is that at low speed with and reduced pressure at the output of my filter owing to the high resistance of sand where my sweep booster pump might draw air and self destructs--so to that end I'm planning to install a gage at that point in the system, watching it carefully til I'm sure the pressure at this point never goes negative

....and run 24 hours....at 24GPM the electricity use should be minimal

To the contrary, bridge, you may have misunderstood my query. Presently at 3 hrs/day 1750 w totals about 5.3 kWh But with the vf if only 200 w is required to achieve 24 gpm then 24 hours still requires 4.8 kWh, virtually no saving whatever. I was hoping for instance that half that period might give comparable results

At 12 hrs/day for instance and $.25/kwhr the new pump will pay for itself in 3-4 years depending on savings at the lower rate of consumption v possible inflation

Therefore I was hoping another participant using vf might confirm my optimism but at 24 hours I might as well send the new pump back for a refund

[lbridges]

...To the contrary, bridge, you may have misunderstood my query. Presently at 3 hrs/day 1750 w totals about 5.3 kWh ...

At three hours a day, I doubt you are turning over the water 1X complete time with a 1 HP pump. My numbers were simple examples. Do you know the flow rate for the 1HP pump?

[dalehileman]

My numbers were simple examples.

Thank you Bridge but as I indicated I had hoped to find a participant with vf who might recommend a minimum

.....doubt you are turning over the water 1X complete time.....

Of course I'm not. For the first 10 years I set it at 2 hrs with pretty good results but only in the past 3 years at 3 hrs to ensure higher FC. Also I now throw in a minimal dose of shock once a week and so far the water stays blue and gorgeous

Probably the running time requirement so rife in the pool forums represents the worst possible case, a public pool in Swaziland used daily by 52 incontinent swimmers including camels and dogs where it's 130F in the winter and overhung by tropical trees shedding poisonous fruit. I'm glad I wasn't attending pool boards when I moved in as I would have been so discouraged about the prospect of maintaining the thing that I would have filled it with dirt and planted potatoes

One source reassures me that at loesst speed I'll need to run my new pump only 6 hours a day though even at 12 hrs I'm perfectly satisfied

My numbers were simple examples. Do you know the flow rate for the 1HP pump?

No, it would probably depend largely on filter resistance, tubing size, etc but it's rated at 3450 rpm

[lbridges]

...No, it would probably depend largely on filter resistance, tubing size, etc but it's rated at 3450 rpm.

Indeed. I'm not versed enough in pumps to estimate your former flow, but you might try finding mas985, who is well versed in pumps and flow rates. Also, you probably know, but just in case - at full speed (3450RPM) the VS/VF series of pumps (same pumps mechanically, only electronics differ) are essentially equivalent to 3hp pumps.

[dalehileman]

Thanks Bridges for that insight and perhaps Mas is listening

It's very encouraging to learn about the apparent efficiency of my existing pump, leading perhaps to the suggested outcome where six hours a day with my new vf might indeed deliver equivalent volume

I'm newly fired up with enthusiasm for its eventual installation but Mack and Sons there's no hurry since the present one was recently overhauled so eons would elapse before we're desperate for a replacement hence on your next visit just lie back and enjoy the brew with the rest of us

...your assurances having taken on significant confirmation to assuage my former skepticism and thanking you profusely for all your past efforts on our behalf

You too Bridge