Pumps - good ones and bad ones.

BuiDoi

Sleepe wrote:

Ok just bought 2 of the eco 8000's I will let you know what I think of them when they arrive.

And unfortunately, that is the ONLY WAY..
but who wants to buy pumps just to prove a point.. we are not "CHOICE"

Pumps built LIKE a pool pump, with real bearings and commercial seals, might last better than semi-sealed cheapies..
But.... at what price the difference and more importantly, at what power difference.

My kintons ECO pump, has a soft start... so I think this is the so called inverter function in operation ..
Imagine the POWER needed to start a column of water moving from being still..

I assume that it is a bit like a battery charger or solar charge controller, where the inverter circuit, supplies just enough power to maintain the RPM.. so low head = lower power, higher head = more power
The Inverter connotation comes from the likely Inversion from AC to DC and then chopping/inverting that to variable frequency.. :dontknow:

Think of an Inverter Air Conditioner, which controls it's compressor speed to maintain the temperature, rather than the thermostat type that is just on/off (not. That a pump will turn on and of normally, to control flow)

Looking forward to your final thoughts... I bought the KJM5000's
..

BuiDoi

rendang wrote:

This is what's so frustrating, I would be happy to pay more to get economy and reliability but it all seems so hit and miss. I guess you just have to pay your money,take your chances and have a spare on hand !

It is quite practical to run a fail-safe system, by using two pumps..
Just have two pumps in parallel, and each with a back flow preventer (flapper valve preferred to spring valve)..
Then just a relay and a flow or pressure sensor, to detect a failure that would drop the relay, powering the second pump.
Just START with the default pump by a manual operation push-button
Either power fail or pressure drop would just drop the relay and the other pump runs.. (assuming power returns - backup power's another issue)

BTW.. to me, the real issue is the AIR supply.. water.circulation is surely not as critical (depending on the fish.. eg. TROUT.. may have issues with increased water muck).. and so maintaining air flow is No.1 for me..
.

Stuart Chignell

BuiDoi wrote:

Sleepe wrote:

Imagine the POWER needed to start a column of water moving from being still..
..

There isn't an initial power requirement to get the water column moving. The initial power requirement is to get the motor moving and over coming the initial friction of the impeller moving through the water.

There is a marginal increase in pressure upstream of the impeller which could cause an slight increase in power use but that would be insignificant to the extra energy to start the motor.

Stuart Chignell

That is assuming that there is an initial spike in energy use.

Physics tells me there must be but Gordon says that when he has measured power use during start up of pumps he hasn't found a spike.

BuiDoi

Stuart Chignell wrote:

That is assuming that there is an initial spike in energy use.

Physics tells me there must be but Gordon says that when he has measured power use during start up of pumps he hasn't found a spike.

There MUST BE a higher start current in motors like pool pumps (capacitor start)

Don't get me wrong on the start power.. it is all very insignificant in the long run..
It's like the old story about flouro' lights.. better to just leave them on than turn on/off as you enter/leave..

I suspect that most of these ECO pumps, with their soft-start technology, would be great for start power .. but again, starting is still insignificant...

Brian

Stuart Chignell wrote:

That is assuming that there is an initial spike in energy use.

Physics tells me there must be but Gordon says that when he has measured power use during start up of pumps he hasn't found a spike.

It is called locked rotor current and by recollection it is usually approximately 6-7 times the run current. Only draws that maximum current for the brief period while it starts turning. On a small pond pump , not long at all

Sleepe

The purchase of the 2 pumps was not for altruistic reasons, I need them for the new system.
While I can get almost everything else not new, I make an exception with the pumps.

mattyoga

you can't equate current magnitude with power in AC systems. The motor starting current is at a low power factor typically meaning most of the current is reactive power not real power.

The energy required to accelerate the impeller and drive shaft to operating speed will be quite small unless a very large impellor/shaft is used.

Gunagulla

Brian wrote:

It is called locked rotor current and by recollection it is usually approximately 6-7 times the run current.

Locked rotor current is what it sounds like- current drawn when the rotor is locked, such as with a positive displacement pump trying to shift a large head of water from start- not a situation that occurs in AP.

Pumps used in AP handle solids, they are not positive displacement (although I guess someone, somewhere may be using one), so all the water drains back through them when they are turned off, meaning the pumps starts with essentially zero load, increasing as the head of water increases up to the outlet height.

I log my system here at 1 second sampling with a good quality data logger, and there are no huge spikes of power draw when the Pondmax 8000 starts, power use increases to max over a second or 2, then is flat until it turns off.

Brian

The locked rotor current will be there on all motors, doesn't matter what is connected to them.

For the time the rotor is stationary as voltage is applied, which in home AP applications, may only be very short, a lot less than 1 sec.

Sleepe

Ok the new pumps have arrived, will be running tests on power consumption and lph @ 1m. Too hot today so next few days. theoretically should get over 6000l at 1m but will be happy at 5k if the power draw is the claimed 75w.

Sleepe

Ok have just tested pump 1 (first box I opened) it pulls 80w this was over a 5 min test (I will be checking the power meter). This is 5w over specs although I am unsure whether this will reduce slightly as the bearings bed in.
Head was tested at 110 to 112 cms, it pushed 20l in 13 sec on a 40mm pvc pipe (I was a little impressed).
I will run this test again then on to pump 2.

BTW Stuart's theory that it does not matter what pipe size you use on a pump I regard as incorrect.

Gunagulla

80W, ok, but what's the power factor? It is only ~20% efficient at 1.1m head @80W.

Size does matter, the larger the pipe, the more volume it will flow for a given input power, although beyond a certain size the improvement will be negligible. However, I'm pretty sure that 'size does not matter' is not Stuart's theory!

Stuart Chignell

Sleepe wrote:

BTW Stuart's theory that it does not matter what pipe size you use on a pump I regard as incorrect.

I would never say it doesn't matter.

The smaller the pipe the less flow.

Sleepe

Ok pump 2, pulls 82w power factor.7(not flash)
I ran both 1 and 2 using the stop watch times came in around 11.9 to 11.93 secs so they are both pushing if my maths are right over 6000lph.
Given the rather agricultural nature of the testing I would say they have underestimated the power pull but I would be a little hesitant stating the pump curve is innacurate.
I am not unhappy about my purchase.

BuiDoi wrote:
Sleepe wrote:
Imagine the POWER needed to start a column of water moving from being still..
..

Apparently we can both misquote each other Stuart. :bootyshake:

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