Advice on Variable Speed Pumps for Spa

[JohnASmith]

I have a 2HP single speed motor/pump now and plan on replacing it with a 3HP variable speed. I like the Pentair IntelliFlo VS. Input would be appreciated. Thanks.

[Watermom]

I'll let someone else help you with this but one thing they will probably need to know is the volume of your pool.

[JohnASmith]

It is only 2,500 gallons but it has 16 jets. It is a large in ground spa. The main reason I want the variable speed is so I can run it longer during times of non use.

[mas985]

The main reason I want the variable speed is so I can run it longer during times of non use.A cheaper option would be to replace your current pump motor with a two speed motor. A two speed pump would allow to run on low speed at off times and it would save quite a bit in energy costs. A VS is really overkill for your situation but if that is the way you want to go, an Intelliflo is a good choice, albeit an expensive choice.

[JohnASmith]

I thought of a 2 speed but it would really need to be 2HP high and 1/2HP low to do what I want and I don't think they make them that way. I also thought of paralleling a second pump with back check valves running only the one needed. Space is a bit tight for that but maybe possible.

[mas985]

HP motor ratings don't tell you much about the performance of a pump. I can show you a 1/2 HP pump that produces more flow rate than a 2 HP pump on the same plumbing. So why do you think a 1/2 HP is the right "size"?

FYI, with a two speed pump, low speed will have about 1/2 the flow rate of high speed but only at 1/4th the wattage.

[JohnASmith]

I would really like to get back to my original question. I am going to change out my 2HP single speed pump for a variable speed pump. My question is, what brand and model is best? I am looking seriously at the Pentair 011017 IntelliFlo. It will do everything my existing pump will do, high volume high pressure for the jet action, plus give me the ability to run it for long periods at low volume which will help keep my pool water clean and mixed when not being used as a spa.

[mas985]

The 011017 is an SVRS which may or may not be required depending on local codes and how your suction side plumbing is designed. Pentair is a good brand and most people are satisfied with it. However, there have been a few where the drive has failed and the repair costs are more than a new pump. Just make sure you use lightning/surge protection on the circuit that drives the pump.

But again, for what you are planning to do, a 2 speed motor for ~$300 pump will accomplish the same thing.

Also keep in mind too, that you really don't need to run a pump for long periods of time to keep a pool clean. There have been studies (http://consensus.fsu.edu/FBC/Pool-Efficiency/FAU-FPL-NSPI_1984_study-efficiency_of_circulation_systems.pdf) which have shown that most pools (and large spas too), can get by with less than 4 hours of run time per day with no noticeable difference in water quality.

You seem set on the VS and that's fine. I just want to make sure you understand all the facts before making that decision. There are a lot of myths going around the industry and one of the biggest myths is that VS saves much more in energy costs than a 2 speed which is simply not true. The difference in cost savings is minimal and is rarely enough to justify the extra cost of the VS pump.

[JohnASmith]

I would think that my 2HP pump is moving at least 100 GPM which means a complete cycle in 25 minutes. I know that is actually conservative because I can drain it empty in far less that 25 minutes, more like 15 minutes.

[BigDave]

One note: I purchased the SVRS version of the Hayward ECOStar and had to ask Hayward - very nicely - for a downgrade to the non-SVRS controller because the SVRS pump saw priming my roof mounted solar panels as an entrapment event and shutdown.

[JohnASmith]

Big Dave, I too have roof mounted solar. I am having trouble understanding how that could effect the controller in a variable speed pump, can you expand on that? Thanks.

[BigDave]

My solar system has a valve (vacuum check?) that lets air in the system to allow the panels and piping to drain back down when not in use. Because of this the panels need to primed each time the controller moves the diverter valve sending the pool water to the panels. While the pipes and panels are filling, the flow rate slows significantly because the pump is overcoming the static head as well as the dynamic head in the piping system. Once the pipes, panels, and return lines are filled, the static head is equalized by the weight of the water in the pipes coming down from the roof.

The SVRS (Safety Vacuum Release System) function saw this low flow to be an entrapment event (somebody stuck in the drain) and shut the pump down to release the suction.

[JohnASmith]

Thanks