Variable speed motor has permanent magnets

Jump to latest Follow Reply
P

PoolChoice

0
In The Industry
Dec 6, 2014
16
Ocala Florida
The variable speed motor has permanent magnets, which 2 speed pump motors do not. The magnet make the motor run cooler, thus longer life, and the magnets make the motor more efficient. A pump is 30% more efficient than the same horsepower motor. The variable speed is not hard to understand, if you keep the manual handy. The Variable speed motor has 8 speeds, which allows more customization, such as having a salt system, pool cleaner or solar. Salt or solar would not work on the low speed, 2 speed.
You would not need the timer with the variable speed.
i think if you download a manual, you will not be over whelmed with the variable.
in replacing the entire pump, the plumbing heights may need to be changed. If the pump(which yours is) is good quality, I would install the motor only.
The impeller will not cause the bubbles, unless it is plugged and you don't have much pool action. Leaks have to be on the suction side of the pump, always check orings on the drain, lid, and suction valves. Cracks in the pump lid may be hard to see, can cause air bubbles. I usually pour water slowly over the suction fittings, if I see small change in the air in the pot, then I am close.

- - - Updated - - -

Sorry i meant to say orings on the winter plug fittings (not drain) ...
 
Re: 2 speed or not 2 speed?

PoolChoice said:
The magnet make the motor run cooler, thus longer life.
Click to expand...
That is only part of the story. A VS motor does not have rotor winding so there is less heat generated there but there are also very high stray currents generated by the drive harmonics so VS motors are prone to arcing across the bearings which can cause failure. Also, the drives used for VS pumps are very sophisticated pieces of high power electronics that are susceptible to failures due especially from power surges. So VS pumps may or may not last any longer than a two speed pump. Based just on the posts from this forum, there seem to be many more VS failures than two speed failures.

A pump is 30% more efficient than the same horsepower motor.
Click to expand...
I have to disagree with this as well. Based upon test data from the APSP and Energy Star, a VS pump is only about 10% more efficient than a single/two speed pump using the same wet end and at the same flow rate.

The simplest thing to do is to just swap out the motor for a two speed. Saves you the hassle of changing plumbing plus it will save just about as much in energy costs as a VS. Especially in TX where you get a lot of lightning which can easily take out a VS drive.
 
Re: 2 speed or not 2 speed?

PoolChoice said:
The variable speed motor has permanent magnets, which 2 speed pump motors do not. The magnet make the motor run cooler, thus longer life, and the magnets make the motor more efficient.
Click to expand...
While many variable speed motors are indeed more efficient due to using permanent magnets, they do not in fact have a longer lifetime. Variable speed motors are more complex and have many additional ways to fail. In practice their lifetime has ended up being shorter on average, even though it has the potential to be longer in principle. The technology simply isn't mature enough yet to see if the longer lifetime concept will ever be possible in practice.

Also, only some of the variable speed pumps have permanent magnets. Many of them use conventional motors, without the energy savings advantage of permanent magnets.
 
Re: 2 speed or not 2 speed?

You make an excellent point about problems with electrical surges. if you are in an area that has electrical/lighting issues, then I may not consider a variable or 2 speed alternative.
I recommend that you may take a look at cost savings on http://www.nrel.gov/docs/fy12osti/54242.pdf
In Florida, we are required to have variable speed motors, if we build new or have 30% renovation, so we learn to accept. As I have sold more variables, pumps and motors, i have not seen many failures. (except for 1 pump brand)
I have also heard many grateful customers, who have seen substantial savings,and hearing of quick payback. My biggest worry was the flow rate for solar and I that has not been the issue, i have them running at a minimum 2100 rpm.
 
PoolChoice,

Electrical surges are not an issue for two speed pumps, only variable speed pumps.

The article you link to makes a valid comparison between single speed pumps and variable speed pumps, but fails to consider two speed pumps. Instead they simply dismiss two speeds in a single paragraph without any justified explanation. Two speed pumps cost much less than variable speed pumps, and save nearly as much electricity, making their payback time much shorter and providing a better deal in the long run for people with low or mid-range electrical rates.

You mentioned above that a two speed is a problem for salt and solar systems. While that is usually true for solar systems, that is only very rarely true for salt systems, nearly all of which will run just fine on low speed.

You mentioned that a timer is not required for a variable speed pump, but that is only true for some of the variable speed pumps. The less expensive variable speeds are often designed without a timer to keep their price down.

You state that in Florida variable speed pumps are required, but that is not the case. Two speed pumps are always permitted, and single speed pumps are sometimes allowed (if they are smaller than 1 HP).

The ideal flow rate for a variable speed pump install is high variable depending on a number of factors. Recommending a minimum of 2100 rpm is not a good general purpose recommendation. Without at least specifying which model of variable speed pump you are talking about it is completely meaningless. Larger variable speeds pumps tend to work at much lower rpm settings than smaller variable speed pumps.
 
The person asking for information, I assume would like other opinions. Which if I would like when i have a question.


I have had bad luck with 2-speed motors, as i have installed and replaced 3 2-speed US Motors for electronic problems. The factory has assured me that changes have been made.
I have installed many US Motor variable speed motors, quite a few Hayward Tri-star, VS models, and Ecostars. I have not had one failure.
You are correct, Florida does allow 3/4 hp, but not popular to even discuss. I haven't seen a variable speed motor without a timer, but thanks for the info.,I'll beware.
The 2100 rpm is based on the 165 US Motor/and Tri-star.
Someone may have reverse experience than me, but i have a Variable speed on my pool, and i ain't changin.
 
I don't know why 3/4 hp are not popular to discuss. Pumps are notoriously oversized, and energy wasting.
No one said you had to change your motor, but the economics don't always make sense, especially where electric cost are less than $.30KHW.

There are many factors that come into play when sizing a pool pump to a specific application. Are there water features, is solar being installed? Is there a SWCG? Pool heater?

The house I purchased came with a single speed 1hp motor, and I've changed it out with a 3/4 hp 2-speed and couldn't be happier. Runs 95% on low. The only time I run on high is to check filter pressure. On high I get 52 gpm and on low about 22 gpm or so. I have no water features.

The wet end of pumps seldom go bad. They may look nasty on the outside, but that the outside. The work is done on the inside. I often wonder how often pumps get changed out when they only need a new motor?
 
When having a response, i should have read earlier post, as I did not assume that Variable speed motors were not liked. They are really the trend in my area, and I have good results and have seen excellent savings. I would not have posted, if I knew i would have to answer every argument about Variable speed pump, again my problem for knowing the established opinion of this web site.
I am not against other pumps, and like the above post, I think the 3/4 hp pump is usually all that needed. The reason I did not mention the 3/4 hp pump, is that i have not sold more than a handful, since selling pumps since 1980. So I have not seen the Florida market, make the 3/4 hp an alternate choice. One reason is suction cleaners are popular, solar is in more homes, customers have spas, and people think that bigger is better. I am glad you are happy with your 3/4 hp and having a good wet end like yours, makes it better.
I am amazed that your heater will run on the low speed, but that is great news.
 
Take a moment to consider what is the best pump for a given situation, rather than what is popular. We have nothing against variable speed pumps, and they are the best choice in some situations, but they were not the best choice in the situation you were originally commenting on.

At low to mid-range electrical costs, a two speed pump is almost always a better choice, while at higher electrical costs a variable speed is a better choice financially. This takes into account the total cost of ownership, rather than just the electrical costs. This balance can be changed in some cases, such as when solar is involved, as low speed rarely works with solar, but holds most of the time.

It is also important to distinguish between your opinions and facts. You appear to prefer variable speed pumps, which is just fine. But you made several factual statements that simply are not true. Saying "I recommend a variable speed pump, I've had great success with them and seen large electrical cost savings" is just fine. But saying that variable speed pumps are required in Florida is simply false and just leads to confusion. There is a great deal of misinformation being pushed out by the pool industry, and we have made it one of our missions to correct these factual errors. At the same time we welcome your opinions, when they are stated as opinions.

Finally, keep in mind that people on the forum are from all over the world. What is true in practice in Florida, isn't always universally true.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Hi PoolChoice,
No one is intentionally picking on you. I promise.

Like Jason says, your opinions and offer of other options are by all means welcome. Like you, I think highly of having all of my options on the table.

Whenever we give advice, often times the advice offered may mean lots of $$ to the pool owner, and so we just want to present factual responses in a effort to proivde the best info we can.

FWIW, I love my VS pump on my small 14,000 ish pool and no solar panels, and I like my 9 cent KWH electric rate too!
I think the VS just plain ol' fun, and I know others here agree. But operationally and financially it makes no sense to have this beast. And I would not necessarily recommend a VS simply because of my personal opinion.

Thats all we are saying, and I hope to see you post more and enjoy the TFP forum.
 
Any savings I get from my VS I'll take, but it isn't what I like most about them. I love the flexibility of adjustment even though that may not be much benefit in itself. It didn't increase my build cost to any significant degree either. I love it, and think it's a nice option to have. I hope mine holds up but only time will tell. I do prefer how quiet it is compared to other single and two speed pumps of the same age and brand. Mostly I like it for the "upgrade" element, much like choosing a car with factory supercharger than not. If you can get it, why not?
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply