Pentair intelliflo ROI model

[Guest]

Decided to apply some financial modeling to the benefits of running a Pentair pump.

Conclusion, even with my high failure rate model factored in, the pump has an incredible return.

http://scriabinop23.blogspot.com/2010/0 ... -pump.html

 

[bk406]

I looked at the link. I'm not a financial person and couldnt understand it. Can you tell us what you concluded, in english

Keep in mind not all states/POCOs will give rebates for pumps. Also, electric rates vary. My 9 cents per kW cost would never justify buying a variable speed pump. No return on investment, IMO

 

[mas985]

In most cases, a two speed pump will have a better ROI than the Intelliflo even though the savings per month is less.

 

[Davegvg]

Based on my experience owning a variable speed pump - I disagree with the ROI models built around intelliflow pumps - Or any true variable speed, or variable flow pump from any manufacturer.

The pumps are excellent, and the intelliflow VF is the best of breed. (I wish I had this vs my jandy epump, but the epump is pretty good as well and has allowed me to make many observations of RPM/watts/Flow/ functionality- tradeoffs)

The ROI is not as robust as any of the manufacturers claim, because in many cases you simply cannot run the pump as slowly as the ROI model indicates to reach XXX savings. This is especially true if one has a SWG, or solar as your minimum speed HAS to be that which the cell will accept or that will overcome the head to push the water up the panels and defeat the vacuum break.

In the Pentairs VF model the savings are based on an unworkably low RPM that would not run any of the above options, and moves so little water as to reduce the skimming capability to almost nothing.

Fact is your pool simply stops "working" below a certain flow rate. Its sustaining this ragged edge of functionality that achieves best savings without turning your pool into a moss pit.

After days of testing this point in my pool is about 200 watts or about 25 watts more than a 1/4 HP pump.
Nice savings from the rior fixed 1hp motor- but not whats claimed and a long way away from the minimum RPM the pump is capable of.

To the other posters point - If one searches around the various pool forums it seems failure rates rise in proportion with reduction of RPM as cooling becomes impaired.

This is not to say you cant save money - because compared to a fixed speed, or even a 2 speed pump you can, but it isnt the ludicrous 90% that the pentair model touts.

"Uncle" Dave

 

[mas985]

Dave,

You totally nailed in on the head. The lower flow rates are only useful for low rate filtering and circulation but not much else. This is true of two speed pumps on low as well. If you have to run at higher speeds for skimming, cleaner, solar, etc, in most cases, it is usually enough time for turnover filtering as well so the amount of run time at the lower speeds is minimal at best and perhaps not even needed in some cases. Low speed is more like a fall back when the pool has not reach the desired turnover and nothing else is required. So when you actaully take into account the time spent at higher speeds, the pay offs take a lot longer. Don't get me wrong, there is still savings with a VS or 2 speed pump, just not as much as one might expect.

 

[chem geek]

In my own pool when switching from a 1 HP (full-rated; 1.65 SF) single-speed pump and 3/4 HP booster pump for the pressure-side pool cleaner to an Intelliflo VF pump for both, my annual electricity cost for the pump(s) was cut by around 50% from $1400 per year to $700 per year. I have a solar system which is why I didn't get more savings since the solar system needs (well, is recommended at) 4 GPM per panel. I could probably save more by going to 3 GPM per panel which is the minimum, but I'm giving a more apples-to-apples comparison as the 1 HP pump was giving at least 5 GPM per panel.

If I didn't have a solar system and could run the pump at a low speed (26 GPM) for one turnover per day, then my annual cost would be around $270 per year so a roughly 80% savings. Getting a 90% savings would have to be a rather extreme example of an oversized pump or bad plumbing (i.e. 1.5" lines). Nevertheless, 80% is pretty significant. Of course, if one compares to a 2-speed pump run at low speed, the savings isn't nearly as dramatic, meaning that the 2-speed pump gets you a lot of the way there in savings though will be more expensive since it's less efficient as the Intelliflo at the lower speeds.

Though the power consumption at very low flow rates drops off, if you factor in the longer time needed for the same number of turnovers it turns out that the Intelliflo operates at around the same cost, at least in my pool, from it's lowest 15 GPM (18 hours at 155 Watts) to 26 GPM (10 hours at 275 Watts). It's only above 26 GPM (for my pool) where the daily power usage climbs.

Richard

 

[Davegvg]

Chem Geek, what kind of skimming action do you get at 155 watts?



Dave

 

[Guest]

In most cases, a two speed pump will have a better ROI than the Intelliflo even though the savings per month is less.

Plug it into the model on Excel and you'll see you are likely wrong about this. Put your monthly savings in there, then reduce your investment cost and you can see the ROI. Off the top of my head, even the best 2 speed pumps are only about $400 cheaper than this pump. Actually, let me correct that: they less than $400 cheaper, as they require a seperate speed control switch, etc. For me, using the Pentair saves me an extra $20/month versus one of those pumps. That is an under 2 year breakeven period, the reset being gravy.

I ended up spending $914 on the pump (no tax and shipping) on Amazon and maybe $50 in pool parts to replumb the thing (didn't have unions before on my setup). Did it myself in about 3 hrs (my first pool pump replacement). Turns out I don't qualify for the SDG&E $200 rebate because 1) I wasn't willing to buy one of the expensive intellitouch/suntouch/etc systems (intermatic simple timer will do just fine for me) and 2) [maybe] I installed it myself and didn't have an authorized guy do it. I would've easily spent $800+ more to have the priviledge of receiving a $200 rebate. No thanks.

The payoff is enormous throwing one of these pumps in, especially if you have a larger pool and live in California (I have a small/medium pool, but pay 30c/kW for my marginal pool pump power). $50/month savings may be conservative.

(I'm still amazed my G3 pool vac works perfectly at 1500rpm. I've yet to tweak to see where it loses pressure. Tells me how much overkill a 1HP single speed pump was.. All that wasted energy on cavitation!)

 

[mas985]

My comment was more about the use of ROI then the absolute savings. ROI as defined by (NPV return - Initial Investment) / (Initial Investment) can be decieving. In your spreadsheet, if a two speed saved $35/month (my estimate) and the Intelliflo saved $50/month, then the two speed would need to cost at least $745 for the ROI to come out the same. Two speeds can be had for much less than that. So while the absolute return of the Intelliflo is more, the relative return to the investment may end up being less.

Also, the ratio of savings between the two cases can vary widely depending on the assumptions used. In your case it may work but I think a lot people would want to have an interface unit and/or controller to fully utilize the Intelliflo speeds and to be able to switch between speeds automatically for solar, in floor cleaners, run time, etc so the cost of the Intelliflo is likely to be more than in your case. After all, what is the point of a variable speed pump if you use only one speed. You may find out that you will end up either changing speeds by hand a lot or always running at a higher speed thereby negating some of the savings.

My only point here is that Intelliflo is not always the clear winner for every scenario.

 

[chem geek]

Chem Geek, what kind of skimming action do you get at 155 watts?

At 15 GPM, skimming action is obviously not good, but as I wrote, I get identical energy consumption per day at 26 GPM so that's what I use when the solar is off (The Pool Cleaner uses 15 GPM, but I don't count that as skimming time as that's done for 2 hours at night; it does skim, but not well and I don't really care). When the solar is on, the 48 GPM gives me extra skimmer action. If I didn't have solar and wanted more skimmer action, I'd probably have the pump run for 30 minutes or perhaps an hour at some higher speed, losing some energy savings, but getting more skimmer action. The nice thing about the Intelliflo pumps is that you can just set these parameters to anything you want, letting you control the energy and cost vs. flow rate and skimmer action trade-off.

Note that I have an electric mostly opaque safety cover so the pool is covered except when used 1-2 hours each weekday and longer on weekends.