Is a pool pump speed controller necessary ?

[Denniswiseman]

Hi John
My heat pump is a 5kw input with 27kw output under good temperature, obviously with the colder weather the output isn't as much plus the fact that it goes into defrost mode a lot more which stops the heating
A COP of 16 sounds as though it would be a lot more efficient but I'm loathe to just change untill something goes wrong with my existing model
I'm in Essex and the pool is fibreglass with sand backfilling, on reflection an insulating material would have been in order maybe some form of sprayed foam insulation before installation

[Teapot]

Hi Dennis, in your situation I wouldn't just swap either, If and when I get around to it I will let you know the results. Interesting the defrost point, hopefully with variable speed the defrost won't need to be as frequent, long etc. I will certainly make a point of asking. Yours must warm up reasonably quickly though with a potential 27 kw? Have you still got the pool running?

[Denniswiseman]

Hi John
Yes I run the pool through out the year but sometimes in the winter the heat pump is on 24/7
This is balanced by the summer months when my retractable cover acts like a green house and I don't need additional heat source
Interested in any info for future reference

[Hsiao Chang]

Hi Hsiao, The interesting point about benefiting pool users and the world. I have converted a few pools to my system using very, very low power because a few people think like us. I expected to be inundated with customers but found the general attitude was "I can afford a pool, so I can afford the running costs" The fact it brings better benefits like cleaner water, less chemical usage and a big monetary saving seems to just pass a lot of people by.
Most of my pool work takes place in France (Europe) there are an estimated 1 million domestic pools in France, If those owners switched to running an eco setup like mine it would save France 2,000,000 tons of CO2 per year. When you sell a house in France you must have an energy survey carried out on the house but not including the pool if it has one. What is the single highest use of electricity? The swimming pool pump.

Welldone John an eco setup saves 2M tons of CO2 per year in France alone, that's remarkable. together we can achieve more .

[Teapot]

Obviously any round number could be questioned, I used a University CO2 calculator for my own figures then just scaled up. With pumps being larger in The US the savings could be far bigger.
I reckon it will take a good few years before people really start to take notice.

[Hsiao Chang]

Obviously any round number could be questioned, I used a University CO2 calculator for my own figures then just scaled up. With pumps being larger in The US the savings could be far bigger.
I reckon it will take a good few years before people really start to take notice.

Hi John, How does a CO2 calculator work ? do you mind sharing a pic of your CO2 calculator with me please ? i am intrigued, if i have one like yours, i can calculate how much CO2 my water pump and heater saves , right ? is the calculation complicated please ? sorry for sooo many questions.

[Teapot]

Hi Hsiao, I just googled for one and got a calculator from a UK university, It was based on UK energy production, we have coal fired and a little nuclear it may well be different where you are. It was working on the power used by any domestic item you keyed in and worked out the amount of CO2 from the various ways of generating electricity in the region. I bet you can find one local to you which maybe more accurate.

[Hsiao Chang]

Thank you John

[Hsiao Chang]

Hi John, Hi Dennis,I got this pump speed controller finally, and it works. they suggested me to buy a power meter so that can read directly the power consumption of it , i let them install it and showed me, when running at max. speed, the meter reads 756W( if i didnt remember wrong ) and when at lowest speed, it reads 100W something like that ....

[Denniswiseman]

Hi Hsiao
Can you post details and costings for others as that seems excellant and can offer alternatives
That is running at full speed it's 3/4 kw down to a light bulb

[Teapot]

Hi Hsiao

That is running at full speed it's 3/4 kw down to a light bulb

Hsiao, whilst you have a power meter fitted, as I have said all the way through you need a flow meter to tell you exactly what the pump is pushing through the system.
Pumps are made with an impeller of the right size and shape to operate at the given RPM. yes you can vary that to a point but too slow and they become inefficient and the flow through the system will be too low to achieve clearing the water. With low batherload pools you can get away with a lot but these are schoolboy errors to assume you can just wind down the pump.
I have had people do just that and they lost control of their pool and had to turn the system back up. Guessing only, you could wind down the RPM by 33%-about 50% of the power safely but with a flow meter you get the real data and you will see when using low power how quickly the flow drops when the filter begins to get dirty, along time before the gauge shows an increase in pressure.

Pool equipment was never designed to be efficient so if you tinker you can end up worse off. When I setup a system the most important part is to monitor the flow at given pump RPM and from that we can setup what works.

I have spent my time designing super efficient pool systems and I know what will work and what won't. My pool runs at 60-69 watts per hour at the proper flow rate to turn over the pool. I am working on a new filter that should improve on that even more and actually backwash properly.

[Hsiao Chang]

Hi John, there will be a flow meter installed for me, i will adjust the speed accordingly to find the right flow. according to your experience, may i ask how many turnovers do you think appropriate per day for a pool with low batherload please?

[Hsiao Chang]

Hi Hsiao
Can you post details and costings for others as that seems excellant and can offer alternatives
That is running at full speed it's 3/4 kw down to a light bulb

Hi Dennis, there was a technical guy who explained me an affinity low, which i googled afterwards, yes, only turning down the speed a little bit, power consumption
drops a lot. that's why when a speed reduced by 50%, power dropped by 80%. and for proper filtration, you dont need a backwash speed.
I bought it through a friend, who knows the manufacturer, so i got a better retail price, 300 USD. but as John put, you will need to have an idea about the actual flow running
through the system, so it's not necessarily you are saving 80%.

[Teapot]

Hi John, there will be a flow meter installed for me, i will adjust the speed accordingly to find the right flow. according to your experience, may i ask how many turnovers do you think appropriate per day for a pool with low batherload please?

Thank you Hsiao, nice to be listened to.
You need to take account of the min flow your heater can have.

From my earlier post I mentioned Gage & Bidwell who mathematically calculated the dilution figure and therefore the filtration level for a given number of passes through a filter.

Gage & Bidwell's law of dilution gives us some expectations on how much water actually makes it through the filter. 1st turnover 63%, 2nd 86%, 3rd 95%, 4th 98%, 5th 99% of the water filtered. There are alternatives but they are all pretty close to one another. Personally I am happy with 4 turnovers per day and that fits nicely with the energy usage.

Is the pool outdoors or indoors?
If it's out doors uncovered then the skimmers only work when the pump is running. So when it's not running dirt enters, sinks to the bottom and requires manual removal.
If you run your pump 24hrs per day then the dirt will get collected and water filtered leading to much cleaner water and less chlorine usage. We would all do this if it were cheap enough but we don't because of the expense, you are now in a different league where it might not cost anymore to run for 24 hours. Indoors you may well benefit from less pump run time.

110m3 turned over 4 times like I do, means a flow of 18.33 m3/hour and that is impossible through your filter. Turned over 3 times, means a flow of 13.73m3/h still impossible through your filter. Turned 2 times, means a flow of 9.16m3/h might just be possible through your filter. Hopefully you see why I said add a second filter?
So outdoors or indoors is very important, covered or uncovered.

I see a lot of pools, I have customers, not all take notice of me. One in particular turns over his pool just once a day, he uses more chlorine but it's swimable, not as clear as mine (1.2 NTU's) closer to 9NTU's, Another pool I converted was 12NTU's when I first saw it and that was hazy but in those days the owners knew no different.
Hope that helps.

Dennis, in our country the units are about £349, sorry I have actually misplaced my price sheet for the minute.

[Hsiao Chang]

Hi John, that's what i am here for, to listen to professionals as i honestly have no idea about the pool system. always grateful for the things you and Dennis told me.
I remember you saying my pump is oversized but filter undersized, my understanding is, because of this, i need a filter to better match flow of the pump can offer, hence 2x450mm filter recommended, did i get this right please ?