Pressure gauge indicates zero during normal operation???

[JamesW]

Everything about the filter looks ok, so maybe the gauge is bad.

In this picture, the pressure is about 4 psi.


This one shows about 10 psi.

The height difference will make about 1 psi difference, so there is still about a 5 psi discrepancy.

14 PSI indicates about 4 psi higher than the other gauge, which is possible due to the pressure in the pump vs. outside the pump.


9" Hg is about 10.2 feet of head.


If the suction is 10.2 feet and the pressure is 23 feet of head, the total is about 33.2 feet and the flow is about 105 GPM.

 

[KCD]

"If the suction is 10.2 feet and the pressure is 23 feet of head, the total is about 33.2 feet and the flow is about 105 GPM."

Pressure is 14 psi x 2.3 ft of head/psi = 32 feet of head and the suction is 10.2 feet of head, total is 42 ft and flow is 90 gpm

I'm using the pressure at the pump drain opening,

 

[JamesW]

Ok.

It seems like the Jandy gauge is reading too low.

Also, the pump is using at least 4 x more power than necessary.

 

[Poolbreh]

Give the filter gauge a good flick, remove and check for any Teflon tape blocking the orifice. Filter gauges can be damaged in shipping.

 

[KCD]

Ok.

It seems like the Jandy gauge is reading too low.

Also, the pump is using at least 4 x more power than necessary.

Can you provide a math model to prove that the pump is using 4x more power than necessary? According to this attached YouTube video, it ain't so. It should state (and prove) the cost per gpm for each pump type (single speed vs variable speed).

 

[JamesW]

The power usage increases by a cube factor for the difference in rpm or flow.

So, if you double the flow, you use 8 times more power.

If you run at 60 gpm for 12 hours at 1,600 watts at $0.25 per kwh, that gives you 43,200 gallons filtered for $4.80 per day or $144.00 per month.

If you run at 30 gpm for 24 hours you filter the same 43,200 gallons at 200 watts for a total of $1.20 per day or $36.00 per month, which is 1/4th the cost.

 

[JamesW]

Also, the Intelliflo pumps that he shows in the video will display the flow and power used, so if he would simply check the display, he would be able to see the actual data and not just whatever he wants to imagine.

The person on the phone is wrong saying that the filter needs 30 psi of pressure to work.

Filters can work just fine at 3 psi.

They say that the pumps deliver 60 psi, which is not true.

The strongest pumps can't get to 40 psi at full speed.

They say that all VFDs are 3 hp, which is not true.

They are using examples from well pumps that have a lot of static head loss.

Most pool systems have 0 static head loss, so the well pump examples are not relevant.

 

[KCD]

To give you an idea of what I’m looking for, the calculations below are cost estimates to run a single speed pool pump for my pool:
(1) Single speed pump runs at an average rate of 80 gpm. (Part of this thread, above, shows how this number was derived using pump curves and pressure gauges connected to the system)
(2) It runs 4 hrs/day.
(3) Weighted gpm of pump = [(4 hrs/day)/(24 hrs/day)] x 80 gpm = 13.3 gpm. (The 80 gpm was weighted to account for a variable speed pump running 24 hrs/day, )
(4) Cost to run pump is $50/month (from utility bill)’
Cost per gallon = [$50/month]/[(80 gal/min)x(60 min/hr)x(4 hr/day)x(30 days/month)] = $0.000086/gal
Cost per gpm (weighted average) = $50/[(4 hrs/day)/(24 hrs/day)x80gpm] = $3.76/gpm
For a given application, comparing the operating cost is a step toward estimating the cost/benefit of pump replacement.
Please provide any calculations or links you have regarding the cost per gallon pumped or cost per gpm for a variable speed pool pump for a typical or actual application.

 

[Jimrahbe]

KCD,

Why would I care in the least what the cost per gallon would be???

If your cost to run your pump is $50 bucks a month and my cost to run my pump is $15 bucks a month, I just don't see the point of knowing, or even caring, how many gallons of water my pump can push through my system.. ??

GPM have nothing to do with preventing algae or sanitizing a pool.

Thanks,

Jim R.

 

[HermanTX]

Please provide any calculations or links you have regarding the cost per gallon pumped or cost per gpm for a variable speed pool pump for a typical or actual application.

I do not understand the importance of this (same as comment from @Jimrahbe ) but for grins - my data is $25.14 per month (or $0.83 per day) to run my VS Pump and it circulates about 47,600 gals per day so the $/gal is $0.000017 if I follow your method. The avg GPM is 33gpm