Swimming Pool Pump Gets Hot

FIRST, is the PUMP getting hot, or is the MOTOR getting hot. Thr pump is the part with the pipes going in and out. The motor has the wires going into it.

Hot motors are OK. Hot pumps are NOT.

Pump on left/motor on right. If your plastic pump housing is hot, you have restricted flow. The pump will fail.

No WAY! Ants! Who would think it?

I say there's nothing like the voice of experience. Welcome to CR4.

I'll throw another GA your way for giving a clear answer to the OP, even though it's symbolic.

_{And, it doesn't hurt that we agree.}

This guy has a question and he could use a second opinion, too: Motors and pool pumps

Please. Your prejudice is showing. Your statement that all Chinese motors are built under specification is simply ridiculous.

Try to hold your hand on a Baldor motor operating at normal efficiency. You can't do it.

Guest is obviously a novice, so don't confuse them with BS. They didn't design the pumps.

Right. A picture of the nameplate and some motor housing temperatures would go a long way toward solving this.

Don't let them push you arround with the prejudice issue. A lot of chinese products are sub-standard and not up to the task. Some of them are good and cheaper than local or others, but it is allways difficult to chose and too late to get a refund for badly manufactured or really cheaply produced items. This covers all branches of the trading and manufacturing: It is a fact that Chinese products are most of the time to be avoided for serious usage and we are constantly being reminded of it in the press and in practice (Contactors and C.Breakers are notorious in creating fires in electrical cabinets not because they were badly wired or undersized but because their contacts and materials are under spec!)...... long list.

Not a single word in this post makes ANY contribution to solving the problem at hand. It just confuses the issue. And the poor OP may even think that you know what you are talking about.

Your prejudice is also showing.

When you did not experience the bad quality of a component that has been sold to you as geniune with even the logo of the good original maker stuck on it with the made in China properly printed, and finally you almost lost a life because it was sub-standard and fraudulently passed as good... then you are not qualified to question or judge the frustration you describe.

The OP has had many good answers up to now and should be able to either solve or re-define his problem for a better response.

(whis I suppose he did ...?)

Good luck to you and your misplaced morales about frauds...

Watt rating is suposed to be equivalent to the H.P. rating (that is if both values are stated on the name plate... which is not usually the case). The nameplate gives the Available power at the shaft of the motor after including all the efficiency / losses. Therefore, H.P. and watt ratings should be convertible.

Good Question!

To the OP. Are you certain the output of the first pump is feeding into the input of the second? And are you certain that both pumps are rotating the correct direction? Either pump by itself should produce some flow in the correct direction, and turning on either one as a second pump should increase the flow. If this does not occur, then there is something wrong with the installation (plumbing or electrical).

One of the 2 pumps will probably be overloaded in the parallel configuration: These are centrifugal pumps therefore, if the 2nd pump is sucking more than what is delivered by the 1st, it might make the 1st run to deliver at the maximum of its curve... more power... ??Heat>

Correction: I meant in series (not parallel!) sorry.

Guest -- Sadly you are like so many other guests that come here with questions. You want people whose time is probably worth in excess of $100 per hour to troubleshoot your problem yet you won't take a few minutes to give a better description of the pumps and piping system they are pumping through. Or even the "What get's hot" question previously raised by one of our premier(and highly tolerant) members.

It is as if you are asking a question in an automotive forum like "my SUV won't start and it's cold outside. What's wrong?" To which the appropriate answer might be "You are an idiot; and a disrespectful one at that". But that was a generic answer. I'll give you the benefit of the doubt; so lavishly spread upon Guests by our well meaning members....

So in this case please tell us more about the pumps( like make/model number/hp/type if you know, etc.) and whether you've mucked with the piping between them and the swimming pool (like hooking everything up with garden hoses).

Ed Weldon (tonight's dinner was a huge success, made more so by a great after dinner sherry)

Check the suction strainer, if blocked, pumps would run hot and flow will be less...

Friends,

About 10 years ago, I revised a swimming pool's circulation system and installed three pumps designed to run in parallel configuration, so during off-hours, one would circulate water through the filter at a slow but OK rate; but during use-hours, two more could be added to boost the filter rate to its maximum. It took a lot of tinkering to get the right combination of impeller power size and machined diameter to eliminate the cavitation when only a single motor was running (very low head pressure and flow rates way off the end of the pump curve) while remaining within the motor's power output rating. I noticed that if the discharge valves were not closed when a pump was turned off, then a pump could be running backwards and continue to do so when turned on to its full speed. Under these conditions, the motor ran hot, the pump was quite noisy, and the overall pool filter rate was (understandably) low.

The original post does not clarify the configuration of the pumps, but if they are running in parallel, perhaps one is running backwards.

Now, before some of you jump on this, remember that this was a typical single-phase type of motor and quite capable of running backwards when started while already turning slowly backwards.

--JMM

There is a short answer to this. You've used it long enough to find the motors getting hot. This indicates that at least the installation is correct.Remeber "hot" is relative. Some people may perceive your hot as normal operating temperature. It is important to check the motor current against the nameplates. Your case sound typical of an undersized pool pump/motor.(Of course you have to ensure there is adequate airflow for the fans.) If it is a new inmstallation, can the fans draw in air into the pool pump cover?

Finally, all motors do run very warm, some warmer or hotter than others. Oh by the way Tobugrynbak the watt is as important as the HP. One (watt) is metric and HP is imperial notation. A watt is .75 of a HP. Thus any motor can be described in either notation. Anyebody in the metric world will know that 75% of any HP will give you the size it watts.

Where have you been? It's been refreshing not having your rude, insulting, arrogant

childish remarks clouding reasonable discussions.

Jerk!

Please friend guest, dont come in here if you're semi@@@@@@@@@.

Read the next post, children wont even post what you just did. What an ignoramus.

I would vote to agree that your answer deserves a GA except for one minor detail:

746 Watts = .746 kW = 1 HP

so 74.6% of a kW = 1 Hp

Wow, I knew that I even though I grew up in a country that still uses a technically inefficient measuring system for most day-to-day purposes.

Correct, a slip or lack of a decimal place. However most posters are logical enough to know when the post gets the "message" across.

No problem, we all make mistakes. In fact, I'm quite sure that if you read some of my old posts that you will find some that I've made myself.

The main point of my post was not to put you down for a math error, but to point out that you responded to an insult of China by insulting every country on earth that has not adopted the metric system into law. It always shames me somewhat when a perfectly simple question from a relatively new member turns into an overblown bigoted argument between people who claim to be professionals.

*Always keep in mind that what sometimes passes for a sense of humor on CR4 either originated from an engineer or someone who finds engineering very interesting... In either case you could say the joke came from someone who is terribly unqualified.

*(Does making the metric system law mean that a person could face a fine or jail term for estimating a hole to be 8 feet deep rather than 2.5 meters? )

thank you all for your answers..

the swimming pool pump is american (STA-RITE) 2 HP (1492 W) and the booster pump is also STA-RITE 1 HP (746 W) . the hot part is the motor not the pump itself .. and it's getting hot after approxemetely 3 hours . I think it's better to have a timer to have a half hour rest ?? I think this will help ??

I don't know I understood from your comments that it's normal for pump motor to get hot , so is that right ?

the pump has been connected by a contactor (20 AMP) (I think it's more than enough ) the wire is standard and the wire distance is not more than 2 meters ??

Measure your current as per the nameplate, if it is as stated, or less, dont worry. If you can measure the temp of the motor casing. Check if the fans get air over the fins. Remember what i said previously, your hot may not be hot at all, as some motors run hotter than others. I include this:

The basic ambient temperature rating point of most motors is 40°C. A motor rated for 40°C is suitable for installation where the normal surrounding air temperature does not exceed 40°C (104°F). This is the starting point.

When the motor operates at full load, it has a certain temperature rise, which adds to the ambient temperature. For example, U frame motors originally had Class A insulation and a maximum temperature rise of 55°C. In a 40°C ambient temperature, this gives an average winding temperature of 95°C. That's 40°C (ambient) ` 55°C (rise). Manufacturers use the 10° difference between 95°C and 105°C rating of Class A insulation to handle the hot spot allowance. If you take a motor designed for a 55°C rise and Class A insulation, and change the insulation to Class B, you have an extra 25°C of thermal capability.

As I said, your installation sounds fine, but do check the elementary and also bear in mind that your booster may be lower than the rating if it is fed by the pool pump, and vice versa.

The idea of installing a timer would provide the cooling and 'Rest' period. I would be curious to hear how my earlier post worked out for you? Data plate information versus the real time current draw and voltages, restriction free flow of water, and are the motor/pump assembly enclosed without amibient (natural) cooling. U must be gettin closer to the concern if there is one! Mark

I'm beginning to see why everyone is struggling with this problem. I did a Google search on the subject of mismatched pumps in series and came up with very little in the way of a simple answer to the generalized problem. I attribute that to the likelihood that mismatched pumps in series is such a poor idea that nobody bothers to discuss the results. Lacking a specific friction head curve on the OP's system and rating curves on the two pumps we're all sort of swinging in the dark. All we know is that this is a swimming pool application where static head is very low and system head as well as pump design is likely the result of the design imperative to keep hardware costs low.

One link, http://www.vibration.org/Presentation/May%202006/Centrifugal%20Pumps%20May%204,%202006.pdf ...gives several examples that to the experienced engineer might provide some insight. A study of the pages showing curves of series and parallel pumps might be useful even though they deal with high static head examples.

Usually when we put centrifugal pumps in series they are actually in the form of several identical impellers on one shaft, so called "multistage" pumps so they can pump against high head pressures. Deep well pumps are a common example.

To get higher flow the accepted practice is to put preferably identical pumps and system components in parallel. To the extent that the pumps may differ some individual "tuning" of either system head or pump speed might be needed to keep each pump operating in its best efficiency range and not running at such an high flow rate (effectively an "open discharge") that it is in the overload regime of its drive motor.

Since there is little we can do to adjust the speed of a swimming pool pump motor the "tuning" would be done by a valve in the discharge line of each parallel pump. Close the valve partially (enough to make a visible change in the flow rate) and observe the temperature the motor settles in at after a period of time. A kitchen cooking thermometer and something like a lump of clay to hold it in place might enable putting numbers on the temperature change.

Now you might say "why don't I try that with the current series setup?". To which I'd suggest you've already created a bad situation. Adding a valve somewhere may help push the operation of the pumps down into a lower power range but will likely be counterproductive given the original purpose was to increase the flow rate of the system. Besides, lacking some practical way of knowing the relationship of the temperature of the motor casing to the all important temperature limits of the internal windings precise measurements of casing temperatures won't do a lot of good.

IMHO if you want to reliably increase the flow rate of your swimming pool system either put the pumps in parallel with an extra discharge gate valve (on the small pump only) which will require you to build the more elaborate piping. Or get a higher output single pump and make sure the current system piping is large enough to handle the extra flow. BTW the discharge valve on the smaller pump can be shut completely off to prevent backflow if you decide that the extra cost of running the second pump is not buying you enough in overall performance and operation of the pool.

Ed Weldon

Check the data plate on the motor/pump assembly for the maximum operating temperatures. Make sure there are no restrictions in the water vessels (pipe/lines). A restriction would create a heavier load on the motors. Are the voltages within the recommended guidelines per the data plate. One other thing would be the location of the pumps? Are they enclosed where they can not get any cooling from the ambient air? Good Luck....Mark

I can't go along with, "A restriction would create a heavier load on the motors."

A restriction in a centrifugal pump will not cause the motor to work harder. Just the opposite is true. Throttle the pump back and amp draw will go down.

A restriction will cause the pump itself to overheat due to insufficient cooling.

100% correct. Centifugal pumps love being throttled, and they run easier. Not good for performance though

Getting hot is is relative term. Please measure the temperature by fixing thermometer on the motor body.For Class "B" insulated motors temp. rise of 80 deg above ambient is permitted. (considering max. ambient of 40 deg.). Please check nameplate data for Class of insulation.

Well in addition to proper maintenance relevant to votage supply and control system... Oh yeah brand and made model it does matters...we already had barbecued chinese pumps.

I am new to the CR4 forum, this is my first read. I have reviewed the many topics and enjoy reading the topics with the understanding, I am sharing the pages and reading the information with intelligent people, answers supplied by intelligent, educated people. I read for example, the swimming pool pump question in which the person asking the question seems very concerned therefore, turned to a community of people who would help him solve a problem, no matter how simple it may be to those who clearly understand and have the answer. I did read the comments and realize there are those who are trying too help, even though some data is missing or it may have a simple answer. Getting to the point, I am most surprised with the amount of bickering and denunciation of other persons or answers. I would not think "professionals" would take time to act in such a way. I hope all the forums and answers are not like this one in particular. I apologize to the author of the pump question, for the unprofessional remarks of those who signed in and thank those who offered sound answers or asked important questions, the real, professional people in other words.

Thanks for registering, and welcome to CR4! Unfortunately, in every group, there are a variety of individuals, some of whom don't concern themselves with how their posts may offend others. You have to learn to ignore those. On the whole, CR4 is a very useful place...

Thank You Fine Line! I am certain that many other professionals enjoying this forum agree.

Mark

Fine line

This is my first read to the CR4 forum as well. I am a Master Electrician with 22 years experience as well as an A.S.E.E. My experiences are very diversified but skill specific in the electrical field and with many state of the art systems. I have been a subject matter expert for the Defense Contract Management Agency for years in Iraq, Kuwait and now Afghanistan. I am in total agreement with your statement and observations. I have also read some statements that are not factual and have actually been condescending to others. The subject of professionalism is important, as well as some patience with those seeking answers or knowledge. I look forward to reading more of your comments, on this site, in the future.

hdhay13

Dear Guest,

A severe churning of water with in the pump is possible.

Please check this and report.

DHAYANANDHAN.S

Note: The Chinese pumps made with lead run cooler then the ones not made with lead! :)

I couldn't help myself we are all sinners.

In Hydronic systems I was taught "Rule of Thumb" Pump motors will run 30 to 40 degrees above ambient/surrounding temperatures.