Is my plumbing efficient? Let's compare Intelliflo VSF stats!

[rhawke]

So I'm really impressed with my Intelliflo VSF pump. I run it 6 hours a day at 1600rpm which the pump tells me yields 25 gpm using 240 watts per hour. For my 14000 gallon pool that means I have a daily turnover rate of 0.64. For a full month this adds up to 42 kWh which costs me $4 per month. I'm happy

But since i negotiated a bunch of pipe size upgrades from my PB and I love stats and data, I wonder if my plumbing is just average or if the upgrades paid off. So I thought I would post my numbers and it would be cool to compare to others.

RPM	GPM	Cartridge Filter PSI	Pump PSI	Watt
1000	4	1	3	56
1200	9	3	4	88
1400	16	5	6	149
1600	25	6	8	245
2000	43	10	12	505
2500	58	15	19	991
3450	82	24	36	2549

Pool Piping:
- Suction: 2 skimmers - 2.5", 1 main drain 3" (75 % closed off)
- Returns: 2.5" to the closets corner of the pool and then 2" loop around the pool
- approx 40 ft from pump to pool edge with 2 x 45 elbows
- Equipment pad: all 2" Schedule 40 PVC

Two anecdotes, that surprised me where I'm curious if anybody has experienced the same:
1) When i go to the full 3450 and then back down to the lower rpms, the gpm increase by about 1-2. At first I thought it was just a random inaccuracy, but I can repeat it every time again. Not sure if the high speed flushes out the pipe somehow to allow more flow at a lower speed afterwards?

2) When I cleaned out my filter for the first time a ton of junk came out. However, for all speeds except the 3450 speed the filter PSI only decreased by about 1 and the pump GPM only increased by about 1gpm and after 3 days I was back where it was before cleaning. Does this mean dirty filters don't really make a big difference on a VS pump? Or is my plumbing somewhere a bigger bottleneck than the filter?

 

[Flying Tivo]

I run 1200@98watts with 1lbs of pressure on SD70 sand filter with Zeolite. 1.5 pipes all around. I also noticed that after backwashing and a lot of junk comes out and my gauge does not even drop 1lbs, it usually stays the same.

Felipe

 

[mknauss]

FYI - turnover in a pool is meaningless. You only need to run your pump long enough each day to create your chlorine (SWCG), or distribute your chlorine (liquid chlorine), skim the surface, and filter the water enough to remove particulates. That could be as little as a couple hours or 24 hours per day.

You can let your filter pressure rise by 25% over clean pressure prior to cleaning. With a sand filter that improves filtration (a slightly dirty sand filter filters better than a clean one), for cartridge and DE filters that standard just reduces the frequency of cleaning.

 

[mas985]

RPM	GPM	Cartridge Filter PSI	Watt
1400	16	5	149
1600	25	6	245
2000	43	9	505
2500	58	13	991
3450	82	22	2549

Pool Piping:
- Suction: 2 skimmers - 2.5", 1 main drain 3" (75 % closed off)
- Returns: 2.5" to the closets corner of the pool and then 2" loop around the pool
- approx 40 ft from pump to pool edge with 2 x 45 elbows
- Equipment pad: all 2" Schedule 40 PVC

With that setup, I would have expected much higher flow rates for each of the RPM. Both wattage and the flow rates indicate significant restriction somewhere. Just for reference, at full speed the Intelliflo produces around 100 GPM with 2" plumbing (Curve-C) and 73 GPM with 1 1/2" plumbing (Curve-A). So with 2.5" plumbing, I would have expect flow rates to be better than that.

What size eyeballs are being used in the returns?

Have you cleaned the filter recently?

 

[jonpcar]

Mark, I thought the same thing based on the experiments that I have done on my pool. Your return question eyeball size could be the issue (as well as making sure his return valves aren’t set to unnecessarily restrict return flows).

Rhawke, looking at your build thread, it seems that the heater is in line for all pool returns, do you have a heater bypass valve? At least one TFPer successfully reduced his pressure loss across the heater by installing one...from that, it seems that at least for some heaters, there could be significant impact to flow rate, not sure if that is your issue. If you use your heater all year this wouldn’t be an option.

 

[JamesW]

5 psi at 1400 rpm is way too high for that big cartridge filter.

I would suspect that the pressure would not register or be 1 or 2 psi.

5 psi indicates an issue on the return side.

What are the pressure readings from the pump at each speed?

 

[rhawke]

Thanks for the feedback. I have updated my original post to include the pump PSI in the table.

Some answers to your questions and additional observations from playing around:

1) Suction Valves: Neither the pump PSI nor the filter PSI change by more than 1 PSI no matter what I do with the SUCTION valves. The GPM does fluctuate based on what I do (e.g. leave only 1 skimmer open, vs 1 skimmer + main drain vs all open) but not by that much. E.g. at 2500 rpm those scenarios kept the GPM between 53 and 59.

2) Return Valves: The pump PSI is mostly unaffected by changing the 3-way valve between Spa and Pool ... only once did it register a PSI change (in all three positions). However, the Filter PSI drops by about 3-5 PSI when both pool and spa are open and when it goes all the way over to spa it increases by 1-2 PSI compared to pool only.

3) My eyeball fittings are open in the SPA (probably a 1 inch hole) and the typical aimable jets in the pool (guessing the opening is around 3/8 - 1/2 inch). Based on this I would have expected the pool mode filter pressure to be higher than spa mode filter pressure but it is the other way around. The spa does have flex piping installed though.

4) I noticed there is some air coming out at the closest return eye ball to the pump, but mainly at the 1600 speed. When I increase, the air goes away.

5) There is a rattling noise coming from the area where the pipes connect into the pool heater. Hard to describe, almost as if something in the pipes is shaking around. It was there since day one but since my parents in law's pool does the same I did not think much of it?

I'll be interested in more of your insights. I will post some equipment pad pics form my phone in a little bit.

 

[jonpcar]

Is this diagram still accurate from your build thread? How much flow resistance does the heater introduce?

 

[rhawke]

almost, except that the suction plumbing is in different order.

from left to right it is now:
3" main drain
2" vacuum line
2.5" skimmer 1
2.5" skimmer 2
-------------
2.5" Spa Drain

i will post pics in a second

 

[JamesW]

I would suggest that you set the pump maximum speed limit to about 2,750 rpm.

For the most part, you should be able to operate at about 25 gpm but ramp up to about 45 gpm when the heater is on.

The pump psi tracks along with the filter psi until you get to full speed. I'm not sure why it diverges so much at full speed.

Pump psi includes the suction psi, so that accounts for part of the difference.

Maybe the suction psi jumps way up at full speed?

 

[rhawke]

Here some pictures

 

[Flying Tivo]

Your setup allows for a very easy bypass of the heater.

Felipe

 

[mas985]

That heater has a builtin bypass so that wouldn't help much.

But it sounds like you have very small eyeballs. Even 1/2" is very small. How many returns are there?

Also, based upon your measurements, there is 12 PSI loss between the pump and the filter which is almost 30' of head loss. There should not be that much head loss between those two points give the plumbing. Either one or both of the gauges is wrong or there is something seriously wrong with the setup.

 

[Arizonarob]

Yup, as Felipe said. In pic 5, a 3 way Jandy valve on the upper pipe coming from your filter, to a T installed on the lower pipe headed to your returns.

 

[JamesW]

The pump psi is the pressure differential between the suction and return. So, it includes the suction head loss whereas the filter pressure only includes the return head loss.

The 12 psi probably mostly comes from the suction side.

 

[Arizonarob]

That heater has a builtin bypass so that wouldn't help much.

But it sounds like you have very small eyeballs. Even 1/2" is very small. How many returns are there?

Also, based upon your measurements, there is 12 PSI loss between the pump and the filter which is almost 30' of head loss. There should not be that much head loss between those two points give the plumbing. Either one or both of the gauges is wrong or there is something seriously wrong with the setup.

Mark, couldn’t he easily verify if the eyeballs are to small by simply removing them, and then take pressure readings??

 

[mas985]

Mark, couldn’t he easily verify if the eyeballs are to small by simply removing them, and then take pressure readings??

Yes but there is no point if there are many returns. Plus what concerns me more is the head loss between the pump and filter. That is likely what is causing the reduced flow rate and efficiency. Assuming the measurements are accurate.

 

[JamesW]

The pump psi is the total head loss. The software uses this along with the rpm and power usage to calculate the flow rate.

The pressure is the total system head, so it is a product of the suction pressure and the discharge pressure. The calculated value is equivalent to Total Dynamic Head (TDH). This value may not correspond with the filter's pressure reading, because it is the TDH across the pump and not the local pressure of the filter.

-From the Intelliflo vsf manual

 

[rhawke]

Thanks for the thoughts! There are a total of 6 returns and I will unscrew the eyeballs next time I'm in the pool just to see what difference (if at all) that makes.

I guess putting in the heater bypass won't help since the heater already has one built in?

Any thoughts on the points 4+5 from my earlier post? Are those both normal?

Thanks for the feedback. I have updated my original post to include the pump PSI in the table.

Some answers to your questions and additional observations from playing around:

1) Suction Valves: Neither the pump PSI nor the filter PSI change by more than 1 PSI no matter what I do with the SUCTION valves. The GPM does fluctuate based on what I do (e.g. leave only 1 skimmer open, vs 1 skimmer + main drain vs all open) but not by that much. E.g. at 2500 rpm those scenarios kept the GPM between 53 and 59.

2) Return Valves: The pump PSI is mostly unaffected by changing the 3-way valve between Spa and Pool ... only once did it register a PSI change (in all three positions). However, the Filter PSI drops by about 3-5 PSI when both pool and spa are open and when it goes all the way over to spa it increases by 1-2 PSI compared to pool only.

3) My eyeball fittings are open in the SPA (probably a 1 inch hole) and the typical aimable jets in the pool (guessing the opening is around 3/8 - 1/2 inch). Based on this I would have expected the pool mode filter pressure to be higher than spa mode filter pressure but it is the other way around. The spa does have flex piping installed though.

4) I noticed there is some air coming out at the closest return eye ball to the pump, but mainly at the 1600 speed. When I increase, the air goes away.

5) There is a rattling noise coming from the area where the pipes connect into the pool heater. Hard to describe, almost as if something in the pipes is shaking around. It was there since day one but since my parents in law's pool does the same I did not think much of it?

 

[mas985]

The pump psi is the total head loss. The software uses this along with the rpm and power usage to calculate the flow rate.

So is this from the pump display?

If so, then there is way too much head loss on the suction side. There should only be about 1-2 PSI loss between the pump and the filter. That might explain #1.

#2 Could be normal

#3 There are 6 returns so less head loss per return since flow rate is split

#4 Due to SWG

#5 Normal - Due to the pressure relief valve on the heater.