what speeds?

[wet_labrador]

okay, so i asked this before, and i sounded like a crazy person. i figured i'd fuel the fire some more.

i think i need 3 settings:

1. chlorinate the pool only, no heat pump.
2. chlorinate the pool while running the heat pump on low speed to slightly heat pool.
3. chlorinate the pool while running the heat pump like a banshee (60gpm is its optimal flow rate).

i want to do this in a way where i maximize electrical savings. when i asked the pb what my head loss was, her only response was that no one in 20 years ever asked such a question. she asked why i cared. i said it was so that i could use the pump curve to pick the most energy efficient rpm for each of those 3 settings.

i do not have a check valve installed, so i can't retrofit a flowmeter. but i suppose i could install some pressure gauges on the pump to measure pressure/suction to determine head loss?

or am i really being crazy and i should just run it at 2400rpm like the pb says?

i have a jandy VSFHP165JEP and a truclear swg.

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she was going on about needing to turn over the water at least once a day given the pool's in full sun, to which i responded that i only intended to run the pump long enough to filter the water or keep the free chlorine at the desired level, whichever took longer, and intended to do so at the lowest possible speed, hopefully reducing the swg output to a lesser output level that runs for a longer time (maybe putting less stress on it?).

 

[cowboycasey]

sounds like a great plan, you just need to "find" the settings by changing the speeds until you find a speed that works for your pool and equipment and then lock them in, most people take a summer to really lock in and find the speeds that work great and use the least amount of power

 

[pooldv]

2400 rpm seems too high, especially for just making chlorine. I thing it is worth spending some time dialing in optimum flow rates for energy savings. Here is where I ended up after some experimentation.

My heat pump manual recommends an optimum entering temp vs leaving temp. I haven't i stalled my heat pump yet so I don't know how many RPM it takes to achieve that. My SWG gives a low flow error at 900 and occasionally at 1000 rpm so I run it at 1100 rpm the majority of the time for skimming, filtering and making chlorine. It uses 150 watts at 1100 rpm. I run at 1950 rpm for solar. I run at 2500 rpm for good bottom drain suction when brushing the pool to the drain.

 

[mas985]

i want to do this in a way where i maximize electrical savings. when i asked the pb what my head loss was, her only response was that no one in 20 years ever asked such a question. she asked why i cared. i said it was so that i could use the pump curve to pick the most energy efficient rpm for each of those 3 settings.

Most efficient speed is 600 RPM.

 

[wet_labrador]

so if i run both the main drains and the skimmers, i get some decent waterflow at 1600rpm. it's certainly not what i was getting at 2800rpm, which is what the pb insists i use. because my pool's irregular shaped, i wonder if i get enough surface movement to properly skim it @1600.

thing is if i switch the valve to main drains only then the pump starts to tick a bit when it's normally very quiet. i can only guess the ticking is caused by a lack of suction and that it's bad for the pump; thoughts?

regarding main drain distance from pump, it's a fairly short run to the main drains: the pool's tucked away in the corner of my property 15' from the back and side. say 17' to be safe. i've seen the piping so i know it's a fairly diagonal run from the main drains to the equipment. so i know from the furtherest main drain to the edge of the pool it's 15' at most, given the blueprints. so that's a 30' long run of pipe that travels roughly 9' upward to the pump. (i used the pythagorean theorem to calculate that estimate).


having all kinds of problems with my equipment, but that's another thread. nothing of my doing, luckily.

 

[mas985]

I would skip the MD and focus on the skimmers. The MD does little for pool water quality. If you shut down the MD, you can run at a lower RPM and have the skimmers work better.

 

[wet_labrador]

thanks for the reply. i'll adjust the valve to draw 100% suction from skimmers. the pb recommended i use the main drains to help circulate the cold water away from the bottom. is there a time other than cleaning where i'd want to activate the main drains?

some other questions:

1) does it seem normal that given my pumps curve of 30gpm@15tdh@1600rpm and 50gpm@10tdh@1600rpm that i would have suction problems?
2) can i go lower, and if so, how do i determine that safely?

 

[mas985]

is there a time other than cleaning where i'd want to activate the main drains?

I wouldn't even bother with that unless you are pushing very tiny pieces of dirt to the MD. MDs clog easily with leaves.

The other use is if you need to drain the pool but they don't really do that well either because pool pumps tend to leak a lot air when the pool level drops that low.

But to get good circulation deep, you don't need a MD. A return pointed down in the deep end will give you much better circulation than the MD will.

1) does it seem normal that given my pumps curve of 30gpm@15tdh@1600rpm and 50gpm@10tdh@1600rpm that i would have suction problems?
2) can i go lower, and if so, how do i determine that safely?

I doubt that is cavitation because you need about 28" HG of suction or 32' of suction head to get that and the head curve at 1600 RPM does not support that. Are you sure the ticking sound is coming from the pump?

And yes, there is no harm going lower in RPM.

 

[wet_labrador]

so when i run my pump @1600rpm, the pump basket has a large bubble at the top. i don't know if that's normal but no matter how much i bleed air from the filter, it doesn't go away. no clue how or where the air is drawn from. i can tell you that when my pb's tech primed the pump, he did not refill the basket, explained the pump did not require it, even though the manual says otherwise. when i run the pump at high speed, say 2800rpm, the large bubble becomes a few short bubbles and with time disappear entirely.

my next hurdle will be trying to figure out how fast i have to run the pump to heat the pool effectively, without running it more than necessary. i'm thinking the window's somewhere between 2400 and 3500. so i plan to start at 2950, wait a week, and if the pool gets to temp, going down to 2700; if still too cold going up to 3200. (logarithmic search).

so i've got my swg set to 70% now, and i'm running it 16 hours a day at 1600rpm; will i need to decrease it's output if the pump speed is increased, given a constant run time of 16 hours per day?

lastly, having disabled the main drains, the weird squeak has gone away @1600rpm. however, whenever the pump shuts down, it let's out a little squeak right before it stops. it's been doing that ever since i got it. unsure what that means.

 

[mas985]

A small bubble in the pump basket won't hurt anything and is fairly typical when running at lower speeds.

my next hurdle will be trying to figure out how fast i have to run the pump to heat the pool effectively, without running it more than necessary. i'm thinking the window's somewhere between 2400 and 3500. so i plan to start at 2950, wait a week, and if the pool gets to temp, going down to 2700; if still too cold going up to 3200. (logarithmic search).

Efficiency of the heat pump may not change that much with flow rate but you could experiment. Lower RPM means more savings for the pump but it could mean more run time for the heater. It might be better to measure the time it takes to raise the pool by 1 degree at different speeds to see if there really is a difference. I suspect it will be very subtle.

so i've got my swg set to 70% now, and i'm running it 16 hours a day at 1600rpm; will i need to decrease it's output if the pump speed is increased, given a constant run time of 16 hours per day?

SWG run time is based upon pump run time but has nothing to do with RPM. Production should be the same at all RPM.

 

[wet_labrador]

thanks, mark. all really helpful replies!

 

[wet_labrador]

i suspect my skimming is ineffective with my vs pump at "low" speeds. i find that even at 1750rpm, the surface water in low end of my pool accumulates debris that doesn't seem to go anywhere. i only observed it for 5-10 minutes and it basically stayed stagnant or moved around in a circle that was no where near the skimmer.

i reckon the struggle to find an effective skimming speed on a low pump setting is due to a lack of necessary returns, improperly placement of existing returns, or both.

maybe a video of the intended speeds: 1250, 1400, 1600, 1750, would help answer whether any of them are acceptable skimming speeds?

at all speeds, there seems to be decent suction in the skimmers, but the water seems dead leading up to them, save for maybe a ribbon around the edges moving at slow speed; can't tell if that ribbon is propelled by returns or wind though, since we get a small breeze now and again.

until i have a more educated solution: i've decided to run my pump for 12 hours a day: 10 of which are @1250rpm strictly for swg chlorination, 2 hours of which are @2600rpm to give my pool has a snowball's chance of skimming action.

my polaris robot seems inept at cleaning the pool; it can't seem to climb up low end walls and generally leaves sand on the bottom of the low end. so i'll have to remedy that to avoid water troubles i reckon.

 

[tucsontico]

The issue of a "stagnant" portion of your pool may simply be the return vents are not aimed correctly. A pump speed of 1750 RPM should produce plenty of "thrust" to circulate the water around to your skimmer. I run my pump at 1600 RPM for my "skimmer only" program and I can watch the debris circulate counterclockwise around my pool to the skimmer. (My pool has an irregular shape–similar to an elongated kidney.) I've run it slower (1200-1400 RPM) but that didn't seem to carry the debris from the far end back to the skimmer.

Good luck!

 

[pooldv]

The goal is to get a circular water flow in the pool. One way usually works better than the other. Aim all the returns one way and give it a few days. Standing there watching leaves go by the skimmer is like watching water boil. Give it a few days and check the skimmers daily. I watch lots of leaves go by with my pump on 1100 rpm but my skimmer baskets always have plenty of leaves in them and very few leaves sink to the bottom.

 

[wet_labrador]

Aim all the returns one way and give it a few days.

Currently the returns all are pointed at 12 oclock. Should I change that? Between the outermost returns in a peninsula, with a return slightly left of the peninsula toward the deep end. There is also a peninsula between the skimmers. The low end return (outermost) has a gulf to its right, so it seems inept at pushing water toward its closest skimmer.

not a perfect picture of my pool, but closest to what i can find. (the company gave it a weird name that yields no results and this was the closest to anything i could find).

I watch lots of leaves go by with my pump on 1100 rpm but my skimmer baskets always have plenty of leaves in them and very few leaves sink to the bottom.

is that the same thing as a bermuda triangle type area from which no leaves seem to leave?

i wonder if my question's already half answered given that my whole backyard's being remodeled and top soil is constantly blowing into my pool -- is presence of top soil on floor evidence that my skimming speed is insufficient (should have made it to skimmer before falling or totally inevitable that it would fall before making to skimmer).

assuming it's inevitably going to fall and avoid skimming, seems like if i just wait 24hours and look to see what's in skimmer vs what debris that normally floats to skimmer made avoided the basket then i can make some decisions about speed. for now i suppose i'll disable the high speed option for a few days and keep increasing the low speed option until filtration starts working, then maybe lock that speed into high speed and go back to 1200 for chlorine generation.

 

[pooldv]

I would point them all to the right and go for a counterclockwise rotation first. I don't think topsoil will float or go to the skimmer.

 

[wet_labrador]

so on low speed for many days, the pump basket doesn't fill with water (though it fills high enough that the impeller? input is fully submerged.
if it interchange high speed and low speed, the pump goes from little bubbles, to a large bubble, to the basket not being full of water.

i noticed on low speed, 1200 rpm that the middle return seems to spurt. like water will spurt out, then slow down, then spurt out, then slow down. suggestions?

i've bled everything there is to bleed and tightened everything there is to tighten.

 

[mas985]

if it interchange high speed and low speed, the pump goes from little bubbles, to a large bubble, to the basket not being full of water.

Immediately? If it takes some time for the bubble to appear (hours), then that is normal. If it happens almost immediately, that is an air leak.

i noticed on low speed, 1200 rpm that the middle return seems to spurt. like water will spurt out, then slow down, then spurt out, then slow down. suggestions?

Are you talking about bubbles from the SWG. On lower speeds, they tend to collect and then come out all at once or periodic spurting.

 

[wet_labrador]

regarding question one: no, not immediately. if i run the pump for a day on 3300rpm, the basket has no bubbles whatsoever. if i stop the pump and run it at 1200 then at first there are no bubbles, the next day there are a few small onces at the surface, then the next day there is a few large ones, the next day the whole cover has a huge bubble, and the next day the water level is below the surface of the skimmer.

regarding question two: out of the return it feels like the pressure in the return changes from high to low, and i can feel a shot of air come out. it seems like it's periodic. i can turn off the swg to see if that stop its it at low speed?

 

[mas985]

regarding question one: no, not immediately. if i run the pump for a day on 3300rpm, the basket has no bubbles whatsoever. if i stop the pump and run it at 1200 then at first there are no bubbles, the next day there are a few small onces at the surface, then the next day there is a few large ones, the next day the whole cover has a huge bubble, and the next day the water level is below the surface of the skimmer.

That has been the experience of many people with two speed and multi-speed pumps. My theory is it is most likely out-gassing of the water (dissolved O, N & CO). The flow rate is not high enough to purge it from the pump basket when on lower speeds so it accumulates over a long period of time.

i can turn off the swg to see if that stop its it at low speed?

Try that. I get bubble spurts when on low speed. It think the gas accumulates in the pipes until it "burps" it out. On high speed it is a steady stream of tiny bubbles. Much like the pump basket, the lower flow rates are not sufficient to purge air/gas in the pipes until it gets large enough where the water can push it out.