Fixed vs Variable speed pump for infinity edge?

[AG001]

Our pool currently has two variable speed pumps, one that runs the main pool water cycling, filter and cleaner and a second that runs an infinity edge with a smaller filter and autofill valve.

Our infinity edge pump died and we're trying to decide on a replacement. We currently run the infinity edge for 3-4 hrs/day, but ideally would like to run it longer if it weren't so expensive to run. I'm trying to figure out if we could buy a lower speed/hp single speed pump (not sure if this is a thing??) or if it's worth the extra money for a variable speed pump. I'm not sure what a variable speed pump buys us in this scenario, given that we aren't changing the speed/flow for cleaning purposes?

Any thoughts would be appreciated. We normally always go for the variable speed, but I'm not sure if there's a better alternative for this application.

 

[mknauss]

Single speed pumps above 1 hp are no longer manufactured for the US market.

A VS pump is the least consumer of electricity for a designated flow rate. What brand and model VS pump did you have? I suspect the Infinity edge needs a high flow rate. That is the nature of the beast.

 

[JoyfulNoise]

A single speed waterfall style pump would work better for that application because you really want low pressure (low head) but high flow rates. Almost all pool pumps are designed to be high head pumps because they need to push lots of water through a restrictive plumbing system.

You could contact a waterfall/pond contractor to see what they use on their systems. Koi ponds tend to needs lots of flow but at low pressure since the filtration in a koi pond is not very restrictive.

Also, what kind of filter do you have on the infinity edge plumbing? If it’s highly restrictive it could be a factor in your high energy use.

If you can post details about your infinity edge plumbing (size of the pipes used, length of pipe runs, filtration, etc), then perhaps @mas985 may have some insights into an appropriate pump replacement.

 

[AG001]

Sigh, I figured it was probably a no go. Our pool guy suggested a single speed since we only run it a few hours a day, but it would be really nice to run it longer.

Our current pump is a 3HP Pentair Variable speed running at 2500 rpm. The filter is the Pentair FNS Plus. Which is also at end of life Pools are expensive!

I'm not sure on pipe size. The run is probably about 75-100ft.

 

[mknauss]

Our current pump is a 3HP Pentair Variable speed running at 2500 rpm.

I would think that is using about 400 watts or so. That is pretty good.

As Joyfulnoise stated, maybe a water fall pump would work better, They run at 1750 rpm and are not effected by the new DOE regulations.

 

[JoyfulNoise]

Are you saying you have an FNS DE style filter on the infinity edge plumbing?

 

[mas985]

Infinity edges require a certain flow rate because of the edge tolerance. So no matter what pump you go with, the cost will not be all that much different because energy use is directly proportional to flow rates. However, the benefit of a VS on an infinity edge is that you have the ability to adjust the flow rate such that it is just sufficient to keep the edge wet. Both a single speed or waterfall pump will probably need to be sized larger than the minimum because there is no adjustment available so energy use will be higher with those than a VS pump (>10%).

My suggestion is to go with an Intelliflo XF pump as it is more efficient on lower head loss plumbing and delivers very high flow rates when necessary.

 

[AG001]

Well crud, it looks like it was a moot question. We planned to move forward with intelliflo variable speed pump, thanks to the recommendations here. Little did I know the variable speed pumps are sold out through 2024! Just nuts. Our pool guy said we shouldn’t use a non pentair pump because they often don’t play well with the controller we have. So it looks like we’re looking at a fixed pump after all.

Really appreciate all of the input and suggestions. Great advice, as usual.

 

[mas985]

DOE regulations now ban manufacturing of large single and two speed pumps. Are you sure you can get one? They may be harder to get than a VS.

 

[JoyfulNoise]

I really find it hard to believe that pumps are sold out until 2024. That sounds like someone giving you a BS excuse to sell you a single speed pump that they have in their stock and they are desperate to get rid of.