Need to replace pool pump motor.

Midwestdude

Active member
Jun 19, 2020
25
Indiana
Ok, so we had our pool renovated and they finished it last Thursday. We had all new coping stones installed, and all new wall tiles. It's a Gunite Pool, that holds 24,000 Gallons. Friday we had swim ready pool water trucked in. So it was anti-climatic going from excitement of having our pool done, filled and ready to switch on the filter and pump. Went to fire it up and nothing. My wife's dad is really good with electrical so he came out Saturday and it took us a while to isolate the where the short was and it turns out the pump motor was the culprit.

So here I am deciding if I want to just find a replacement motor or buy a new pump and motor combo. My pump and the deceased motor are old, and I mean really old as you can see from the pictures below. All I've been able to tell about the pump is that it is a Pentair Purex. The only label I found lists the Model # as AM-4 and a serial number of 824 Purex Pool Products Division. The motor's label was more helpful I was able to find that a Century B121 motor would be a suitable replacement motor. However given the age of both the pump and the motor, I'm starting to wonder if it would be better to just replace this with a pump/motor combo. But if I do this, I admit I'm a little lost in knowing what I need. I see terms like GPM (gallons per min), head foot measurements, maximum flow rates etc.

Here's what I do know:
Piping (at leas above ground) is 1 1/2" PVC
Filter is a Pentair Tagelus TA-60A/60D sand filter with a designed flow rate of 60 GPM with a max pressure of 50 PSI
The pump motor is a Century Centurion switchless motor rated at 3/4 HP 3450 RPM that can be wired as either a 115 or a 230. Ours was wired for 115.
Our pool has 1 skimmer and 2 return jets.
Pool size is 18' x 32' with a 9' deep end, and a 4' shallow, that holds around 24,000 Gal.

I'm not sure what all to look for in a new pump/motor combo. I'm leaning towards replacing both so they are both new. I know that I want to get a setup that will run under the filter's max flow rate of 60GPM. But when shopping most pump motor combos are listed just by HP. Question is, is the HP the motor runs at the main factor I should consider? If so, I think I should stick with a 3/4 HP combo. I can take a photo of the plumbing setup we have running to and from the pump and filter. Would it be better to just replace the motor or am I right in leaning towards all new?

IMG_0247.jpegIMG_0248.jpeg
IMG_0244.jpegIMG_0342.jpeg

Along with replacing the pump motor or combo, is we have to rebuild all the wire connections and boxes. Things were not wired well. Below is a picture of the power setup. The switch at the top right is for the pool light, the box to the bottom right below the light switch is for a non-GFI double outlet, then the box at the bottom left had a combo switch and GFI single outlet that turned the pump on or off. The switch for the pump is where the wires come in from the garage, then travels to the non-gif, then to the light switch, then to the large box that we are guessing is a junction box (we can't find a way to open it. and then feeds through the galvanized piping which runs into the ground and I assume to the light. When we removed the switch we found that the back of the switch was burned/melted and the so were the wires coming out of it. Thankful we didn't have a fire. They also didn't properly weatherproof all the boxes... We'll clean all that up with new proper wiring.

IMG_0692.jpeg
 

ajw22

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Jul 21, 2013
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Get the Pentair Superflo VS pump or Hayward Maxflo VS. They can run on 120V and you adjust the speed for the GPM that works in your pool.


 

Midwestdude

Active member
Jun 19, 2020
25
Indiana
A few issues with variable speed pumps for us. Most of them are $1,000 plus which not really in our price range at this time. Another issue is most seem to be for hard wired 230V wiring. We only have 115V wiring available in our pump's location. Another concern I have is our current pump runs at 3/4 HP and our filter and 1 1/2" plumbing has a max flow rate of 60 GPM. A variable speed pump running at at 1.5 HP is double the horsepower we are currently using which worries me about overwhelming our sand filter. The other factor is this "Feet of Head" measurement that I have no idea how I can calculate as I have no idea how much footage of underground piping we have, so I feel like I'm guessing at this and that worries me. How do I measure what I can't see? So those curve charts that list Feet of Head on the vertical and Flow rates listed along the horizontal seem useless to me if I don't know the feet of head. I know what it represents in that it is a way to calculate resistance to flow.

Another issue is that most of them I have read self install voids the warranty.

These are the pumps I'm looking at that are 3/4 HP. Hayward and Pentair are brands I'm familiar with, Sta-Rite I've never heard of but I'm also new to pool equipment.

 
Last edited:

ajw22

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Jul 21, 2013
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A few issues with variable speed pumps for us.

A few issues with what you said...


Most of them are $1,000 plus which not really in our price range at this time.

A VS pump run at low speed giving less than 3/4 HP in flow will save you in energy costs more than the difference in price.

Another issue is most seem to be for hard wired 230V wiring. We only have 115V wiring available in our pump's location.

Both pumps I linked to in post #2 run on 120V.

Another concern I have is our current pump runs at 3/4 HP and our filter and 1 1/2" plumbing has a max flow rate of 60 GPM.

You run a VS pump at low speed to give you your 60GPM or less and it will use a lot less energy then a 3/4 HP SS pump.

A variable speed pump running at at 1.5 HP is double the horsepower we are currently using which worries me about overwhelming our sand filter.

You never have to run your VS pump at full speed.

The other factor is this "Feet of Head" measurement that I have no idea how I can calculate as I have no idea how much footage of underground piping we have, so I feel like I'm guessing at this and that worries me. How do I measure what I can't see? So those curve charts that list Feet of Head on the vertical and Flow rates listed along the horizontal seem useless to me if I don't know the feet of head. I know what it represents in that it is a way to calculate resistance to flow.

It doesn't matter with a VS pump. You adjust the speed to give you the flow you need.

Another issue is that most of them I have read self install voids the warranty.

The DIY warranty on the Pentair and Hayward pumps I linked to in post #2 will be the same as what you listed. Ask Doneys if they can get the VS pumps for you.

These are the pumps I'm looking at that are 3/4 HP. Hayward and Pentair are brands I'm familiar with, Sta-Rite I've never heard of but I'm also new to pool equipment.


Sta-Rite is a Pentair pump. It is evidential to a Pentair pump except for the shape and branding.

You got a lot of choices. Good luck with whatever you decide.
 

JamesW

TFP Expert
Mar 2, 2011
27,002

The motor is from May of 1991.​


That's 30 years old, which is a lot longer than you will get from a new motor.

The pump looks older, but it's hard to tell.

1626208296236.png

Dating a Century Motor​

The following table allows a date of manufacture to be determined for any Century motor manufactured between 1938 and 2010. The Serial Number as stamped on the data plate will consist of one or two letters followed by one or two digits. The letter(s)s can be looked up in the table below. The digits indicate the month: 1=January, 2=February, etc.

1626208025674.png
1626208153247.png
 

Midwestdude

Active member
Jun 19, 2020
25
Indiana
A few issues with what you said...




A VS pump run at low speed giving less than 3/4 HP in flow will save you in energy costs more than the difference in price.



Both pumps I linked to in post #2 run on 120V.



You run a VS pump at low speed to give you your 60GPM or less and it will use a lot less energy then a 3/4 HP SS pump.



You never have to run your VS pump at full speed.



It doesn't matter with a VS pump. You adjust the speed to give you the flow you need.



The DIY warranty on the Pentair and Hayward pumps I linked to in post #2 will be the same as what you listed. Ask Doneys if they can get the VS pumps for you.



Sta-Rite is a Pentair pump. It is evidential to a Pentair pump except for the shape and branding.

You got a lot of choices. Good luck with whatever you decide.
Thank you for the information. My wife's Dad who is an excellent plumber and electrician though he's not an officially licensed one. I'd be confident in his help installing a pump. If I do go for the variable speed pump I'm weighing the pros and cons to the warranty being void for self install. Sounds like at best the warranty would be 1 year for the Hayward, and Pentair seems to give you 60 days for self install and possible extended warranty with "qualified installation."

Doheny does carry both the Pentair SupeFlo VS and the Hayward MaxFlo VS. Warranty and install aside between the Pentair SuperFlo and the Hayward MaxFlo, which variable speed pump is the better overall product?

I did find this interesting under the question section on the item page for the Pentair variable speed pump. Sounds like there is a possibility that they would extend some kind of warranty for the Hayward MaxFlo. I posted a question in the item page for the Hayward pump directly asking about the warranty situation for self install.

Screen Shot 2021-07-13 at 9.10.38 PM.png
 

Rancho Cost-a-Lotta

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Apr 10, 2018
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If you choose a Pentair pump from an authorized E-Commerce dealer, you get an additional one-year parts only warranty. Eligible Pentair products have model numbers that start with "EC."

 

reggiehammond

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Oct 4, 2020
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Thank you for the information. My wife's Dad who is an excellent plumber and electrician though he's not an officially licensed one. I'd be confident in his help installing a pump. If I do go for the variable speed pump I'm weighing the pros and cons to the warranty being void for self install. Sounds like at best the warranty would be 1 year for the Hayward, and Pentair seems to give you 60 days for self install and possible extended warranty with "qualified installation."
Just wanted to chime in with encouragement - I’m a total moron with basically zero handy experience and I’ve in the past 2 years:
* Replaced SS pump with Intelliflo VSF
* Replaced leaking DE filter with new Quad DE 60 Filter
* Installed a SWCG
* Removed a Polaris PB4-60 Booster and tied it’s return piping into my filtered flow

This stuff is NOT rocket science, at all. You can do it!
 

ajw22

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Jul 21, 2013
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Both the Pentair SuperFlo VS and the Hayward MaxFlo VS are equally good. Lots of us are partial to Pentair products due to better support and parts availability.

We don’t hear much about pumps failing with the first year to worry about warranty support. Lots of folks here have DIY Pentair pumps without problems.
 

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Midwestdude

Active member
Jun 19, 2020
25
Indiana
Both the Pentair SuperFlo VS and the Hayward MaxFlo VS are equally good. Lots of us are partial to Pentair products due to better support and parts availability.

We don’t hear much about pumps failing with the first year to worry about warranty support. Lots of folks here have DIY Pentair pumps without problems.
Good customer support is worth a lot these days. Of the two brands I am leaning towards Pentair. This thread has put my mind at ease a little as far a s self installing. Even with a professional install the warranties aren't long and from what I can tell are a bit limited. I had also emailed the pool company that did our renovation and his recommendation was a variable speed pump between 1 and 1 1/2HP along with a flow meter to help us dial in the flow.

I like how much energy you can save running a VS pump at lower RPM's vs a single speed pump at a higher RPM. I'd probably have to kick up the speed when using the suction side vacuum. Next season we have talked about chaining to a robotic pool cleaner.
 

ajw22

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I had also emailed the pool company that did our renovation and his recommendation was a variable speed pump between 1 and 1 1/2HP along with a flow meter to help us dial in the flow.

Here is what your pool company guy does not understand.

Running a higher HP VS pump at a lower RPM is more energy efficient. A 2 to 3 HP VS pump will save you more then a 1 to 1.5 HP VS pump.

Let's say you need the RPM that uses 1/2 HP for your flow. A 1 HP pump will need to run at half speed. A 1.5 HP pump will need to run at 1/3 speed. A 2 HP pump will need to run at 1/4 speed. A 3 HP pump will need to run at 1/8 speed. All those will give you the 1/2 HP flow you need.

All motors run at about 3400 rpm. So the 1 HP pump will run at 1700 rpm while the 3 HP pump will run at about 600 rpm. A motor running at 600 rpm uses much less energy then one running at 1700 rpm.

This is a long way of saying you are better off getting a 2 HP or so VS pump then a smaller one. You will run it slower and it will use less energy.
 
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Midwestdude

Active member
Jun 19, 2020
25
Indiana
Here is what your pool company guy does not understand.

Running a higher HP VS pump at a lower RPM is more energy efficient. A 2 to 3 HP VS pump will save you more then a 1 to 1.5 HP VS pump.

Let's say you need the RPM that uses 1/2 HP for your flow. A 1 HP pump will need to run at half speed. A 1.5 HP pump will need to run at 1/3 speed. A 2 HP pump will need to run at 1/4 speed. A 3 HP pump will need to run at 1/8 speed. All those will give you the 1/2 HP flow you need.

All motors run at about 3400 rpm. So the 1 HP pump will run at 1700 rpm while the 3 HP pump will run at about 600 rpm. A motor running at 600 rpm uses much less energy then one running at 1700 rpm.

This is a long way of saying you are better off getting a 2 HP or so VS pump then a smaller one. You will run it slower and it will use less energy.
That makes a lot of sense to me. Initially I was thinking I had to match the motor/pump specs as closely as possible. Because in my uninformed thinking higher HP=faster flow=overwhelming my sand filter. And I had visions of sand blowing out my return jets and killing my sand filter. Doesn't help that some of the videos I watched on YouTube initially fed that fear. I've learned a great deal from this thread. Being our second season as pool owners and neither of us having had a pool to maintain till we moved here, we're still somewhere on the learning curve. Knowing now that all motors regardless of HP run at their fastest all run at the same RPM which is what makes variable speed pumps so energy efficient to set their speed at whatever RPM you need for your system's flow saving a lot of money on energy costs. It certainly opens up the field of options when choosing a pump, rather than limiting myself to outdated less efficient tech.

I do have a question about the timers. Our old system didn't have a timer I manually turn it on or off and my timer is my watch, phone, or clock on the wall. I'm assuming with these newer pumps because they seem to all have a 24 hour clock, I can set a timer for the pump to turn on or off at specific times or say turn on at a specific time and run for x number hours. Or can I just run it 24/7. Can you also program it to change RPM's as needed like having it run most of the 24/7 schedule at one RPM and then kick up for a period of time and then return to a base RPM?
 

ajw22

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Jul 21, 2013
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I do have a question about the timers. Our old system didn't have a timer I manually turn it on or off and my timer is my watch, phone, or clock on the wall. I'm assuming with these newer pumps because they seem to all have a 24 hour clock, I can set a timer for the pump to turn on or off at specific times or say turn on at a specific time and run for x number hours.

Most VS pumps have a built in control panel and timer. Some VS pumps, like from Jandy, are made to connect to automation panels and have no built in control panel.

If you have a SWG and no automation then you need a timer for the SWG.

The VS pump power should not be on a timer and should be continuously powered.

Or can I just run it 24/7.

You can. I do. The cost for running the pump at low speed is so little I let my pump and SWG run 24/7.

Can you also program it to change RPM's as needed like having it run most of the 24/7 schedule at one RPM and then kick up for a period of time and then return to a base RPM?

Yes.
 
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