Variable or 2-speed for SWG pool?

[Plazaglass]

The builder we're considering has specified a two-speed pump, but are there reasons to consider a variable speed instead for a small salt water pool?

 

[jblizzle]

A VS might save a little more electricity and allow you to dial in the flow rate you want.

But, the VS is more prone to problems with nearby lightning strikes. So, in FL, if you go VS you should add surge protection as well.

Do you have an special high flow needs? If not, the Whisperflo 2-speed is likely oversized which will use more power than you need.

 

[Plazaglass]

No special high flow needs here. So do I understand you, that a variable speed could be less costly because it will allow a lower speed than the lowest speed on a two-speed? (Wow, that's a lot of "speeds"!)

 

[jblizzle]

A 2-speed runs at full speed (3650) or half speed (1825 rpm). At half speed it is moving 1/2 the water and using 1/4 the power of high speed.

A VS is often most efficient down at 1000 rpm (although that might be too slow and not enough flow for your SWG to work). If you save 75% on power dropping from high speed to half speed, that only gives you 25% of the electrical left to save. So dropping from 1825 to 1000 might only save you 15% more than just going from high to low.

So, the 2-speed gets you a bulk of the energy savings (and less worry about lightning and not needing the surge protection).
The VS will get you a little more electrical savings, but might need to buy the surge protection and the VS pump costs more up front.

What size Whisperflo are you specked for? At the most you would need the 0.75 HP. And really you could save more by just getting a 1HP Superflo 2-speed which is a smaller pump that will use less power than the Whisperflo.

 

[Plazaglass]

Thank you for the explanation, Jason.

I emailed the builder to ask about the Whisperflo size spec and this was her response:

"That is determined by the county...based on gpm, size of plumbing distance from pump and spec on pump"

I thought that was a little odd, since she was out here to do the estimate, but maybe that's a normal response to such as question?

In any case, with a pool as tiny as the one we're planning on, and the fact that the pump equipment will be maybe 12 feet from the pool, seems like your 1HP Superflo two-speed is a good solution.

 

[WASP]

Thank you for the explanation, Jason.

I emailed the builder to ask about the Whisperflo size spec and this was her response:

"That is determined by the county...based on gpm, size of plumbing distance from pump and spec on pump"

I thought that was a little odd, since she was out here to do the estimate, but maybe that's a normal response to such as question?

In any case, with a pool as tiny as the one we're planning on, and the fact that the pump equipment will be maybe 12 feet from the pool, seems like your 1HP Superflo two-speed is a good solution.

Sounds odd to me too.

Give the county a call and tell them your trying to understand how to select the most energy efficient/cost effective option for your pool.

 

[cowboycasey]

I love my superflo 340042 and I am about the same distance away

Amazon.com : Pentair 340042 SuperFlo High Performance Energy Efficient Two Speed Pool Pump, 1 Horsepower, 230 Volt, 1 Phase - Energy Star Certified : Swimming Pool Water Pumps : Patio, Lawn Garden

 

[pooldv]

I will bet a buck fifty that if you call the county and ask them to make a recommendation to you about a pool pump the silence will be deafening. :-D

 

[Plazaglass]

Thanks, everybody!

I've just emailed the pool builder to ask about the SuperFlo.

Mary

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I will bet a buck fifty that if you call the county and ask them to make a recommendation to you about a pool pump the silence will be deafening. :-D

No doubt!