Variable speed or multiple single speed pumps

[Teapot]

Hi Mike, Yes that's the pump. Yes people don't often grasp that their pumps draw more than they expect as 1hp=0.745 watts. Interesting on your increased energy consumption on the 90 degree turn, if the power of the pump is reduced the energy of the 90 degree turn will reduce. It is systematic of the size of the pumps used to simply push a little bit of water around. Out of interest what is the reading on your pressure gauge, mine is only just 0.5 psi and I had to buy gauges 0-15psi for use on mine and my customers systems, the excess is just dynamic head and friction which are a waste of energy. You'll not the Blue Eco does not have a fan on the rear of the motor hence lower sound level, in my case 29db, sound levels being another wasted energy.
On Chemgeek's pool he increased pump flow to circulate water through the roof mounted solar panels, if that additional power was put through a heat pump it would provide a fair amount of heat in his case, I forget the figures but it was surprising.

[Mike_Snoo]

Installed the flow meter today. I have a flow of 42 gpm. The pressure reading on top of the filter says 23 psi. I will install the variable speed pump soon and make some more measurements.

[Teapot]

Hi Mike, That is pretty much the text book (my empirical data) what I was expecting. I run tests on my customers pools as standard when I meet them and despite big pumps the actual flow figures are pretty much what you have found and in the smaller pumped versions similiar flow but with less system pressure. Now take a look at the data plate on your filter, what does the manufacturer state? With sand filters it's usaully 40-50% lower than the manufacturer states but most pool builders just don't know or understand this. There is a trend in the US to have big pumps and small filters, in Europe we tend to do the reverse.
Looking forward to your next post.

[Mike_Snoo]

Very interesting. I installed the variable speed pump and started my first measurements. If I run the Pump on 100hz it consumes around 410Watt and I get a flow of 25gpm. The filter reading is 8.1 PSI.

Means this pump is in this setting with no flow optimization is 3 times more efficient. I will follow up with more information.

[Mike_Snoo]

So, I made my final experiment with the current set up and the variable speed pump.
Seems like as slower the pump as more efficient it runs.

V cal. and A cal. means a calibrated measuring device. All other values was measured with a different device.

[Teapot]

Hi Mike, have you looked at Pump affinity laws? Yes is the answer and why I headed off in a different direction to most of the pool industry as the filtration improves by a factor of 4 as the flow and therefore the pressure is reduced. Think of a chef producing a clear consome, if he was to squeeze the filter to say 14 psi the result would be a cloudy liquid.
The energy saving can be partially used to run filtration for longer thus more floating debris is removed before it sinks and gaining better more complete filtration and partly to realise a massive cost saving, pumps etc will last longer as well.
Max power is need to backwash to expand the media bed in the case of a sand filter but not so fierce as to loose filter media.

[Mike_Snoo]

Hi Teapot,
I have not heard about the pump affinity laws. But I googled it. Besides that I can guesstimate what the power consumption, flow,.. before I change something, I don't know what that would help me. I don't design a pump, I can measure the real world effect.

I am almost done with re plumbing my pool. Here is a interesting thing. The pump uses now with same speed settings more energy than before, but it has a significant higher flow! So I put a few diagrams together.

However, for whatever reason I don't get flow with 60hz anymore.