To keep Pump running or not..that is the question

[putercoder]

This is my second season owning an inground pool. I have a Hayward Pump. When the service can this year to open the pool, the seemingly knowledgeable tech suggested that I leave the pump/filter running and not to turn it off all season. He suggested that using the timer to run the pump for periods of the day/night reduces the life of the pump as condensation builds up in the pump when the pump is turned off due to the pump being warm and the warm ambient temperatures. This condensation, he claims, reduces the life of the internal bearings. He said for me to decide which is cheaper the electricity or the pump replacement.

Is there any fact to this claim?

Am I wasting electricity or reducing the pumps life by running it non stop.

What is the better way?

thanks

 

[Johnl]

I'm not sure if it's true or not. I've never heard that before.

I've had my pool for 5 years and had the bearings replaced on the motor last year because it was starting to get loud. I would be surprised if 4+ years of increased electrical use would be cheaper than running the motor on a timer (in my case 10 hrs per day).

However, when I had the motor reparied they did recommend detaching the motor from the pump and bringing it in doors for the winter to extend its life. I'm not sure where your at, but we have hard freezes here in PA.

Hope that helps.

 

[DWSPool]

I haven't heard that recommendation either. If condensation were a real concern, you would think that would hold true for many other motors, including car engines, etc, and I don't recall anyone suggesting we should keep our car engines running overnight

There may be some value in avoiding cycling your pump off and on several times a day, since startup is more wearing on motors/engines than continuous running - however, off/on cycling once or twice a day should be ok.

Any mechanical experts out there want to chime in on this one?

 

[DWSPool]

 

[Melt In The Sun]

That's not the dumbest thing I've ever heard, but close. Condensation forms on cold things, not warm. I assume he meant that it forms on the inside of the motor due to cooler temperatures outside the motor casing? Even if that does happen (which I don't think is true), it would happen even more with the motor running all the time. Don't worry about it.

 

[beaumatt]

I run my pump 24/7 at the advice of my PB as well. He did not mention anything about condensation, but told me that cycling off and on with a timer could lead to problems if the pump lost prime and I was not around to rectify the situation. It seems to me that MANY folks here have theirs on timers with no ill effects, but I am too chicken to try it. I am in my 11th season and this is the third pump I have had, with 4 years being my average. There is my $.02.

 

[Beez]

I run my pump 24/7 at the advice of my PB as well. He did not mention anything about condensation, but told me that cycling off and on with a timer could lead to problems if the pump lost prime and I was not around to rectify the situation. It seems to me that MANY folks here have theirs on timers with no ill effects, but I am too chicken to try it. I am in my 11th season and this is the third pump I have had, with 4 years being my average. There is my $.02.

Not to be argumentative, but your experience would lead me to believe that running 24/7 would shorten pump life, not extend it. My guess is that most of us run our pumps on timers, and most of our pumps are significantly older than 4 years.

 

[svenpup]

This has been discussed on TFP many times. My opinion is that, yes, starting the motor is the hardest part of the motor's life, but I don't think that it means leaving it on 24/7 going to translate to much longer pump life. I like richards comment from this thread:

I have to wonder about whether the wear is that significant. I work in a garage, and our air compressor starts and stops all day long. I worked in the last shop for 14 years and we never changed the motor the whole time I worked there. It was capacitor start, if that makes a difference, but still, it had a rough life starting every ten minutes or so.

I replaced the motor on my pump with a very high-end, high-efficiency, two speed for around $220. It wouldn't take many extra hours of run time to spend more than that on electricity.

So what is the motivation? If it is to save money, 24/7 probably isn't the best choice. If it is to make the motor last as long as possible without considering cost, it is still unclear if 24/7 is the best choice. I personally like a long run time on low speed, but nowhere near 24/7.

 

[JasonLion]

A motor that is left running all the time will (on average) last longer than a motor that is turned on and off (but see below). The difference is measurable, but not huge, perhaps 30% (again, see below). However, there are two problems with interpreting this as "leave the pump running all the time" that completely invalidate that advice. The first is that the pump won't last enough longer to even begin to pay back the cost of the electricity you waste by running the pump more.

The second issue is a little more technical, but also completely invalidates the whole argument. The pump will last longer when measured in hours turned on, but it won't last longer when measured in years of calendar time. For example, if you run the pump 24x7 it might last say 10 years of continuous use. If you only run the pump 12 hours a day, it might last 7 years of motor running time (shorter than the 10 years mentioned previously) but that is 14 years of calendar time!

Of course motors fail for many different reasons. The reasoning above doesn't apply to each of the individual ways a motor can fail, even though it is true on average across many motors. Some specific motor may fail after six months regardless of how much it is used, another might last 20 years even if it is constantly being turned on and off.

Likewise, specific situations relating to a particular install may change the odds a little. Motors exposed to rain won't last nearly as long as motors inside an equipment shed. A motor exposed to rain benefits more from being left running (still not enough to pay for the electricity), compared to a motor that is inside. But no common situation can change the odds enough to justify leaving a pump running all the time when you don't otherwise need to because of water quality issues.

 

[dfenrick]

Hey, welcome here.

Without knowing a few more details like pool size and where you live, it's hard to give you any accurate feedback, but if we make a few assumptions, it's fairly easy to guess whether the tech was right or not.

It's unlikely that the bearings in a pump will die from condensation. Although we don't know all the details of the pump that you have, it's safe to say that generally swimming pool pumps are specifically designed to run in humid conditions, and are unlikely to fail from a bit of moisture or condensation. If you poke around long enough here, you will see some photos of some pretty rusty pumps that sit outside all year, and run fine for many years. I'm sure that someone could come up with some pathological case where the conditions would be just right for the pump (really the motor) to fail due to cycling, but that notwithstanding, in virtually any practical installation running the pump less will save you money.


Here is an example based on a typical Hayward 1 HP superpump.

For this example we will assume...

Electrical draw is .75 kW (according to the manual)
Electricity cost of $0.15 / kW hour...
Typical pump replacement cost $343 -- determined by an exhaustive google search grabbing the first price I saw

Typical cost of operation would be.

.......................Hours / Day...........6.............8............12.........24
Cost / Day..................................$0.68.....$0.90.......$1.35.......$2.70
Cost / Month.............................$20.25....$27.00......$40.50......$81.00
3 months..................................$60.75....$81.00.....$121.00....$243.00
6 months.................................$121.50...$162.00....$243.00....$486.00
9 months.................................$182.25...$243.00....$364.00....$729.00


As you can see, if you run 12 hours / day instead of 24, you would save more than the cost of the pump within 9 months. At 8 hours instead of 24, you would save the cost in just over 6 months.

Depending on where you live, those 6-9 months may take two or three calendar years to use. On the other hand, if you live where it is warm, you may save the cost of a pump within the first year.

 

[geekgranny]

I'm prefacing this with I put in a new Intelliflo VF this spring, not because of any type of failure to the old pump but for electrical savings and adjustability for different features. The old pump was running very quietly; always has. Challenger 2.23 SFHP (service factor plus horse power) and was way too much pump, and electrical cost, for normal filtering operations.

For the most part my main pumps have run around 20 hours a day, rarely less. Old pump was one or two cycles a day, varied. New pump, which is too new to comment on, three cycles a day for 21/7 run time. But it is a VF (no jolting start), flooded (always primed), and runs on very low speed virtually all the time.

The pool is now 29 years old. We inherited it when is was 5 years old when we purchased the house. The Challenger was on a timer from the very beginning. The wet end may be the original or only replaced once. The motor end may be only the second motor but maybe the third. If it its the third each motor lasted an average of 10 years. The motor that is on the old pump now could have many more years of life left in it. If the motor is only the second one that's an average of over 15 years per motor, taking into consideration that the motor on it now was running perfectly and extremely quietly when it was removed from system this spring.

Here are some of the conditions under which the pump ran: 1) being "flooded" (way below pool), 2) way undersized DE filter, 3) 1.5" pipes, both ways 4) running year round most years, 5) immense amounts of sand/silt/dust going through it, 6) sitting idle some years, during winter with pool turning into a swamp 6) several of those swamp years pump used to clean a lot of the gunk out of pool (required impeller clean outs) , 7) It never ran dry because in flooded situation it is always primed, 8) weekly backwashes (sudden shock to pump turn it on and off several times during a short period of time) 9) went through a few hard freezes undrained without pump running, 10) pump not exposed to any sunlight but plenty of air circulation being under deck; mostly protected from rain except for the small amount that goes through the small spaces between deck boards.

I just remembered..... the third motor for main pump was put in around 2001, (second pump was running perfectly and quietly) when a house/pet/plant sitter did a backwash and forgot to open the valves back up. The pump ran for days with no water to it except maybe back through the Polaris, with that the only valve being open. It was still humming when we got home but as soon as I turned it off it wouldn't start back up.

The Challenger has had A.O Smith motors.

The Polaris booster pump around 25 years or so old has had only three motors, same wet end probably. The last replacement was Summer 2009 so the first two motor averaged about 12 years each. The booster pump has always been on a timer run minimum 10 hours per day, one cycle, most years year round.

I'm thinking that the most positive factor for the main pump is/was being "flooded" and/or protected from the elements.

My good friend has a 22 year old pool. Pump on timer but far less fine debris going through it than mine but constant juniper needles, and until this year, no skimmer socks to keep the needles going to pump/impeller/filter. Pumping station sits 6 ft above surface of pool. Until this year when I started helping her with her pool, when I would go over there the pump was running almost dry from almost totally clogged skimmers; some water coming from main drain but pump pot "looked" dry, pump noisy, filter pressure near 0 and mostly filled with air. I don't know why she hasn't gone through bunches of motors and wet ends as the impeller was frequently clogged over the years. She is on her second or third, only, motor. Challenger/A.O. Smith motor, not sure of SFHP. Her pumping station gets rained on but is mostly protected from sun.

Perhaps these Challenger pumps, A.O. Smith motors, are really as "tough" as the manufacturer claims.

gg=alice

 

[4JawChuck]

In my career I likely have rebuilt thousands of pumps and thousands of mechanical seals, pump run time is only one factor to consider in the life of a pump. Mechanical seal life is more dependant on the number of stop and start cycles than the motor bearings as a bearings life is rated on load, rotational speed and run time. Ball roller bearings are very tolerant of start and stops.

If the motor is kept covered and out of the rain you will have no problems with condensation, inside a sealed box would be a problem not an open air install. In general starting a stopping a pump and motor everyday twice will save you energy that overcomes the extra cost of replacement at least two fold, the challenge is when a pump is started and stopped many times per day such as a sump pump seeing a lot of ground water.

My recommendation is keep a simple rain shield above the motor to keep the rain off it or if its in a shed make sure there is plenty of air circulation and condensation will not be an issue. The typical usage scenario of a twice daily on and off cycle for a pool centrifugal pump is not enough to shorten a pumps life significantly especially in comparison to the energy savings. As long as the pump does not lose its prime everytime it shuts off the mechanical seal life will be satisfactory also, they don't work for long with out liquid to form the water seal which needs to form in the first split second of operation, as long as the seal is submerged in water it is fine even if the pump is purging air due to loss of prime...it is the dry condition that is deleterious.

Put a timer on it, keep it dry and out of the rain and it will save you money in the long run compared to running continuously.