Variable speed pump efficiency

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HeavyD328

Member
Feb 8, 2019
12
San Diego
Hi all,

This is my very first post here and also happens to be the very first pool that I have ever owned or managed! I just had a new pool completed and started up just over a week ago. However, I've had some questions about in particular about what kind of efficiency I should expect out of my pool pump that the PB has been pretty vague in answering. The pool is rectangular with a built-in spa, probably no more than 15,000 gallons with no special water features. The setup for the pool is:

Pentair Easy Touch
Pentair IntellifloXF VSF
Pentair Mastertemp 400
Pentair Intellichlor IC40
Pentair D.E. 80 filter
Ecosun solar pool heater 380 sf

One thing that I've noticed is that the flow rate seems to be extremely low for the performance curves of the intellifloXF provided by Pentair and rates at which other users in this forum have stated work well for their pools. I've looked at the minimum flow rates required for these products, and with the minimum 25 gpm required by the intellichlor, I need to set my pump at 2500 RPM to meet that flow. With the minimum 40 gpm required for the Mastertemp 400, that would be close to 3000 RPM. Even when I max out the pump at 3450 RPM, I am only getting 49 gpm according to the screen logic app. It seems like other people on this forum are running at much lower pump speeds yet still achieving good flow rates. I've asked the service tech for my PB about this and he states that these flows are very normal and will improve once the temperature warms up, which to me I don't buy based on what I've read on here. On top of this, since the plaster is still curing, I'm not doing any heating through the mastertemp, solar heater, nor is the intellichlor being used right now.

Am I crazy or does this seem incredibly inefficient? I figured that with a variable speed pump I would be saving a lot in electrical costs but according to the speeds it looks like this pump needs to run it will be pretty costly. Is there something I should be worried about or are these speeds and flows normal real world performance numbers. Again, being the first pool I've owned and managed I'm not sure what to expect.
 
Welcome to TFP and congratulations on your new pool.

Flow rates really don’t matter. All you need is sufficient flow to close the flow switch on the IC40 and pressure switch on the heater. That should be around 1500 rpm.

When you can start the SWG & heater, after your pool is 30 days old, you find the lowest RPM thst closes the switches and add 100 rpm.
 
328,

Welcome to TFP... A great place to find all the answers to your "weak flow" questions... :shark:

We have some pretty good pump and fluid dynamics guys here, so let's see if we can get their ideas.. First, we will need you to post some pictures of your plumbing at the equipment pad. This will give us some idea of the water path through your system. Also, need to know what your filter pressure is at various speeds.

Thanks,

Jim R.
 
Here are some pictures of them equipment pad. I'll try to get some numbers of pump and filter pressure at various speeds this weekend as I am at work most of the day today.

Thanks guys
 

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328,

How do you select between your main drain and skimmer(s)?

What position is your backwash valve in? May not be, but it appears to be in the backwash position. :scratch:

I'd like to see the plumbing between your filter and your heater..

How many returns does your pool have and what size is the eyeball opening?

Thanks,

Jim R.
 
The slide valve can be used on a sand/quad de or a FNS DE filter.

For sand or quad de, the handle is up for "Filter" and down for "Backwash" with the waste on top.

For FNS DE, the slide valve is down for "Filter" and up for "Backwash" with the waste on bottom.
 
Here are filter pressures with the pump running at various speeds. I couldn't figure out how to get the pump pressures to display on the pump keypad as it says display not active with the Easytouch connected. I tried to turn off the easytouch but that didn't seem to do anything.

1700 RPM (15 GPM) - 9 PSI
2000 RPM (24 GPM) - 11 PSI
2200 RPM (28 GPM) - 12 PSI
2400 RPM (31 GPM) - 14 PSI
2600 RPM (35 GPM) - 15 PSI
2800 RPM (38 GPM) - 17 PSI
3000 RPM (42 GPM) - 19 PSI
3200 RPM (46 GPM) - 21 PSI
3450 RPM (50 GPM) - 24 PSI

The PB actually sent a Pentair rep to take a look at the equipment yesterday. The short of it is that he said everything was working perfectly and essentially told me not to believe what flow rate the screen logic app says and the pump is delivering at specific RPM and that their algorithm is probably wonky for calculating this?! Said it's better to just set strictly on RPM and everything is working as expected from his vast experience working with many pools.

The rep then set up a schedule on the Easytouch he said should work well for out pool as follows:
8am-5pm at 1700 RPM for filtering
8-9 am and 4-5pm at 35 GPM for cleaning (I asked him why he set a specific flow for this one even though he just said not to because it's unreliable and he said the vacuum works at this speed so it's fine....this equates to about 2600 RPM)
8-9 am and 3-4pm at 2740 RPM for the spillway

That was his suggested schedule and then he said that when it comes time to activate the SWG he would run it at 100% and during the times that the spillway and vacuum were running this likely would produce enough chlorine. He also set the pool solar at 2900 RPM and said that would be optimal.

Some of my observations and questions are:
The suction vacuum moves if I have the pump set at 2200 RPM so can I just use that speed for cleaning? Forgot to mention but had an autocover installed so expect minimal debris

When the spillway is on the suction vacuum moves so isn't cleaning being done during this time? Or is it necessary to set up different cleaning and spillway times as the Pentair rep did?

Jim, I attached a photo of the plumbing from the filter to the heater. Looks like there are 5 return lines. To me it looks like the main drain is attached to the front port of the skimmer? Not entirely sure about this and the valve is basically set halfway.
 

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HeavyD328 said:
1700 RPM (15 GPM) - 9 PSI
2000 RPM (24 GPM) - 11 PSI
2200 RPM (28 GPM) - 12 PSI
2400 RPM (31 GPM) - 14 PSI
2600 RPM (35 GPM) - 15 PSI
2800 RPM (38 GPM) - 17 PSI
3000 RPM (42 GPM) - 19 PSI
3200 RPM (46 GPM) - 21 PSI
3450 RPM (50 GPM) - 24 PSI

The PB actually sent a Pentair rep to take a look at the equipment yesterday. The short of it is that he said everything was working perfectly and essentially told me not to believe what flow rate the screen logic app says and the pump is delivering at specific RPM and that their algorithm is probably wonky for calculating this?! Said it's better to just set strictly on RPM and everything is working as expected from his vast experience working with many pools.
Click to expand...
Yes, the pump does calculate the flow rate from the RPM and the wattage used but it tends to be fairly close to reality. 50 GPM indicates to me there is something seriously wrong with the setup. With 2" plumbing, that pump should be getting over 100 GPM. What does the "Pump Pressure" readout on the display show when at full speed? Also, what is the wattage at full speed?
 
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Ok, putting the Easytouch into service mode worked. So here are are the filter and pump pressures I'm getting at various speeds.

1700 RPM (15 GPM) - 9 PSI (filter) - 10 PSI (pump)
2000 RPM (24 GPM) - 11 PSI (filter) - 15 PSI (pump)
2200 RPM (28 GPM) - 12 PSI (filter) - 17 PSI (pump)
2400 RPM (31 GPM) - 14 PSI (filter) - 20 PSI (pump)
2600 RPM (35 GPM) - 15 PSI (filter) - 23 PSI (pump)
2800 RPM (38 GPM) - 17 PSI (filter) - 27 PSI (pump)
3000 RPM (42 GPM) - 19 PSI (filter) - 30 PSI (pump)
3200 RPM (46 GPM) - 21 PSI (filter) - 34 PSI (pump)
3450 RPM (50 GPM) - 24 PSI (filter) -40 PSI (pump)

At 3450 RPM, power consumption is 2337 watts.
 
That is over 90' of TDH! There is something significantly restricting float in the setup. Are the check valves fully opening on full speed?
 
It would seem that the suction might be the issue if you have 40 psi total and only 24 psi at the filter.

There might be something wrong with the slide valve, but that's not common.

I would have plumbed directly into the filter with no valve.

The quad de can't be backwashed effectively anyway.

There might be a problem with the check valve between the pump and the filter but that's unlikely.

Are the pump and skimmer baskets clean?

You can look through the clear window on the check valve to see if the flapper goes all the way up.

Does the pump sound like it's pumping gravel at full speed?
 
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