Replacing single speed pump with variable speed - savings?

[ttmatsu]

Opinions on IntelliFlo VF versus Tristar Energy Solutions?

I have a pool that holds about 32K gallons with a spa. Plumbing is 2 inch pipe. Currently have a 1.5 HP single speed pump for filtration with a simple time clock and a 2 HP pump for the spa jets. I currently have a rooftop solar (2 stories up) but am taking it down for a solar PV system and will just rely on a solar cover (kids grown up and we don't use the pool that much anymore). So replacement pump will just handle suction side vac (Hayward navigator - although I will check out The Poolcleaner recommended by poolguyNJ when it wears out it's wings and pads) and filtration. Figure I'll program for 2 hours of vac/skimming and rest of time for slow filtration with a variable speed pump.

I searched and no one seems to have a Tristar Energy Solution in this forum. I realize it has a standard induction motor versus the DC permanent magnet motor for the IntelliFlo but a quote I got had a $700 difference in cost (installed) between IntelliFlo VF and the Tristar.

I see JasonLion says the IntelliFlo is the better pump but didn't lay out why.

The Hayward savings calculator says that for 1 turnover, my current pump should run 8.2 hours and the Tristar should run 14.9 and it will save me $686.14/year (close to 50% savings). The Pentair calculator says my current pump should run 9.4 hours for 1 turnover and if I set the Speed to 1700 RPM (yields closest runtime to Tristar - 15.1 hours), I would save $1,303/yr. The Pentair estimate of savings is outrageously optimistic as I figure my energy cost is 1.5kwh X $0.27 X 9.4 hours X 365 = $1389.56 which would be a 94% savings. From what I've read, a 70% savings is realistic and this would be $972.69. To be apples to apples, using the Hayward runtime of 8.2 hours for my pump, the savings for the VF would be $848.52 @ 70% savings). I don't know what to adjust the Hayward numbers by but their number seems realistic since theoretically, they are not as efficient as IntelliFlo. So the difference in cost between the two would be covered in 4.3 years. The installed cost of the VF would be paid off in 1.75 years (at 70% savings). The payback on the Tristar would be 1.2 years. Are the estimates I'm using reasonable? I didn't overcomplicate the calculation by factoring in that I run 8 hours for 6 months and 4 to 6 hours the rest of the time so my actual payback will be a little longer.

The reason I'm looking at the VF rather than the SVRS is it makes more sense to me to know the flow rate versus setting a RPM (I don't have a flow meter) and it seems like it is easier to play with the settings using GPM. I can easily figure out cost and runtimes when I change the GPM and set according to what makes sense for my situation. Like in the winter, I can quarter the run time by telling it my pool is 1/4 its actual size (I live in San Diego) - according to my pool guy, that should be fine for water quality in winter.

Oh, noise or sound of the motor is another factor. I have no idea how loud the Tristar would be for the 2 hours I set it to vac/skim while people on the forum seem to indicate the Pentair is still fairly quiet. Pool equipment is fairly close to my bedroom window and main patio area.

 

[JasonLion]

Welcome to TFP!

All of the variable speed pumps are extremely quiet when run on low speeds.

The savings calculators make a great number of assumptions, many of them different between the two calculators, and neither of them likely to match any specific situation exactly. Both of them will be wildly wrong more often as they are even approximately correct. The differences in the calculated savings have little, if anything, to do with the differences in the pumps. They are all about the different assumptions made in each calculator.

The IntelliFlo has a higher inherent efficiency because of the special design of the motor. That means it will take less electricity to move the same amount of water in a given time. This difference is small compared to the difference between a variable speed pump and a single speed pump. Most of your savings will be because you get a variable speed pump, and then there will be a small additional savings on top of that if you get the IntelliFlo. Because the IntelliFlo is more expensive in most situations, that means they are about equally cost effective (in most situations).

There are two big differences between them. One: the IntelliFlo has been around for longer and they have had more time to work out the kinks and bugs in their software. There were many problems with the IntelliFlo in the first year, but now they have proven to be reliable and well understood. The variable speed TriStar just started shipping relatively recently and does not have much of a track record. It may still have first year problems, like the IntelliFlo did, though no issues have come to light just yet.

The other big difference is in how they interface to automation systems. The IntelliFlo is designed to be controlled by a Pentair brand automation controller. The VF does have a fairly fancy timer built-in, but for external control you really want a Pentair branded automation system. Pentair does sell a quite expensive interface that allows other brands of automation system to control the IntelliFlo, but it's pricing and design both make that approach unreasonably expensive. The variable speed TriStar comes in two versions, one designed to be controlled by any automation system that can support a two speed pump, and the other that provides additional control features when used with a recently produced AquaLogic or ProLogic control system.

If you have a recently manufactured Pentair or Hayward/Goldline automation system it makes a lot of sense to get the pump from the corresponding manufacturer. The pumps are both designed to work with their same brand automation system and provide numerous features in that configuration that are not available when using a different brand of automation system. Older automation systems are often lacking the necessary firmware to work with variable speed pumps and upgrades can be expensive.

For use with older automation systems that do not support variable speed pumps the variable speed TriStar has an advantage because it comes in a version which works well with older controllers that know how to support two speed pumps (which almost all of them do).

On the other hand, if you want to use the pump without an automation system, the IntelliFlo SVRS and VF have a large advantage as they both include fancy built-in timers that can control the pump speed.

Only the IntelliFlo VF has the built-in flow meter and can be programmed to support constant flow rate modes. This feature makes the VF much easier to setup for maximum energy savings. When properly setup any of the other variable speed pumps can match the energy savings, but it takes more fiddling to figure out the ideal speed on the other pumps. On the other hand, if you fail to clean your filter when it should be cleaned with a VF you can end up running at higher speeds and spending more money on electricity. The counterpoint being that other pumps wouldn't have enough circulation to keep the pool clean in the same situation.

Finally, there are various situations where a variable speed pump will provide much less energy savings than you might at first assume. Solar heating systems, in-floor cleaning systems, and relatively large water features can all require relatively high flow rates, which cancel out much of the savings that might otherwise be possible with a variable speed pump. Variable speed pumps save the most money when run on very low speeds.

The big unknown right at the moment is what the reliability will be on the TriStar. For the moment they are relatively new and might therefore have "first year" problems. Still, no problems have shown up so far, and there may not turn out be any problems. Only time will tell.

 

[PoolGuyNJ]

The VS-SVRS and VF Intelliflo models have built in timers (up to 8 events) so the Intermatic timer can be removed. No automation needed. They can give you all the info that the Hayward would need automation to give you.

The motor type differences on the Intelliflo vs Hayward is very significant, sealed vs. unsealed. Assuming the electrical connections are water tight, the Intelliflo could be submerged and still operate. This could happen in if the yard flooded. Being sealed also ensures no dirt can get in. The variable frequency drive, or VFD, and permanent magnet design of the Intelliflow ensure less wasted heat vs. the Hayward's induction motor. The motor, if the drive allowed, is designed to go to 8 HP but is limited by the drive to 3 HP. That means that even though the parts inside such as the bearings and coils can handle it, they will never see that stress and will last longer. This can't be said of the Hayward motor. The Pentair will also run cooler due to lower power loss and higher efficiencies. The MTBF between motor failures for the two brands is very significant in favor of the Pentair.

The motor speed on the Intelliflo is slower for a given flow rate and will use less power typically, even though the motor is more powerful. That power is simply held in reserve.

The SVRS model vs the Hayward with a discretely attached SVRS system is usually less money, and simpler/more reliable. This is important with new construction code requirements.

Are the price deltas really, when you think about it, real or when looked at from 5000', perceived? The energy savings, longer MTBF times, and potentially simplified equipment pad are telling factors.

Scott

 

[mas985]

I put together a pump cost comparison spreadsheet that allows you to control some of the input parameters and make sure they are the same between pumps. Currently it is set up for two runtimes (low and high speed). One thing you will notice is that lifetime savings really is not all that much different between pumps including two speed pumps. However, the VS pumps do give you a lot more control if that is what is needed.

Here is the thread where you can download the spreadsheet.

As for which pump is better, I think you will get a lot of different opinions from forums like this. It is a bit too early to determine which pump will have better long term reliability since they have not been around long enough to really tell how long they will last although the Intelliflo has been around the longest.

However, because of the addition of high power electronics, it stands to reason that all VS pumps will probably not be as reliable as a standard pump. Some Intelliflo owners have already posted about failed drives but given the pumps have been around 5 years already, that is probably reasonable.

Personally, I am not convinced the Intelliflo is the best VS out there. I'm not sure which one is. However, I would at least talk with a company called Hybrid Pumps. If nothing else, the owner has a lot of good technical background and some very interesting insights into the Intelliflo pump.

As Jason pointed out one key item to consider is what your controller will support, if you have one at all. That can make a big difference in terms of lifetime cost. Also, I think a controller is a good idea if you really want to make use of multiple speeds and the flexibility a VS pump offers. At $0.27/kwh are you in Califorinia? If so, that is another reason to get a controller, the state will help pay for the pump.

 

[ttmatsu]

Thanks for your insight and responses.

I guess the big worry about the Hayward is reliability and Scott says that Pentair pumps have much better reliability than Hayward. But I'm guessing the Hayward is much easier to service/repair than the VF. I'm worried that Pentair owners have started reporting failures.

I ran Mark's Scenario 2 using a Sta-rite 1.5 HP pump along with the VS/VF, Jandy ePump and Hayward Mark already populated in the spreadsheet and Curve A. I changed the $/kwh to .27, % turnover on high to .23 to get as close to 2 hours as possible and % turnover on low to .52 (75% turnover which is close to my yearly average runtime of 6 hours per day). This results in running on high for 2.01 hours and 12.61 hours on low. The VF/VS would save me $63.17 per month while the Hayward would yield $60.62. The Jandy is the best at $64.92. But after rebate, the cost of the Hayward is $800 while the VF is $1500 (installed). Over the 10 year simulation, the NPV of the savings has the Hayward on top by a very slim margin. They are all very close.

I'm checking out the Hybrid X2. simicrintz from Pool Service Technologies lives within 10 miles of me so he invited me to check out his X2 so I can hear what his pump is like at higher load.

 

[ttmatsu]

Well Scott, the guy that handles my pool repairs also said not to get the Hayward so I am down to the VF or the Hybrid X2. A company that does a lot of pump upgrades in my area said that Hayward will probably introduce a Pentair type motor in a couple of years and the current offering is just so they can have a variable speed on the market and that's why it is quite a bit less than the other models. He also thinks that once Hayward introduces a PM type motor, that the HFD/VFD type pumps will be the low cost option. But the X2 costs as much as a VS so I don't see it as a lower cost option.

 

[jeeman]

Which one did you go with?

I have a 15k-20k gallon pool with an A.O. Smith Centurion motor (1.5HP/1.5 SF). This controls the flow to the pool and spa (not the spa jets, which has a dedicated pump). I'm thinking of replacing with a VS, using the same timer box that I have now which just turns the pump and heater on/off by killing the power.

I'm seeing the VS 3050 on Amazon for $795, and the VF for $1200. The $400+ difference in price is making me shy away from the VF, especially since the electrical savings is marginal.

Jeeman