Replacement pool pump system; please advise!

[e1836936]

I have a 15x30 in ground pool with built in over-flow spa (separate spa blower not currently working but I'd like to repair or replace). Approx 15,000 gallons of water. I need to replace my Magnetek Century Centurion 3/4hp pool & spa pump; it's old, inefficient, leaking, has wiring issues & sounds like it's dying but the filter case is in OK shape lol and I replaced the C-1100 filter cartridge in February.

I was quoted by local pool guys for the same size 3/4hp with no filter upgrade but also given options for 1hp, 1.5hp & Variable Speed with & without filter upgrades i.e. C1750 & C2000 as well as systems with salt generator upto 40,000ga. The reason given for me needing a 1 or 1.5 hp is I have the built-in over-flow spa with a separate blower and if I "want to use the spa to it's full potential (which I do), I need 1 to 1.5 hp".

I have no idea how anything including the spa blower worked in the past with this pump, I can't even get the pool light to work. lol FWIW, I'm looking to add an automatic pool cleaner to the system too, like Hayward Navigator or XL OR one of the Kreepy Kraulys.

All of your thoughts and advice are greatly appreciated.
THANKS!

 

[Bama Rambler]

Without knowing more about the spa and it's requirements we can't recommend a pump. If you'll list everything you can about the spa including type, size and number of jets and the size and length of the plumbing maybe Mark (mas985) will look at it and make a recommendation.

 

[e1836936]

Great, thanks!

Spa Details:
Type: Built in, over-flow
Size: 4' x 7'
Number of jets: 5
Size of the plumbing: 1.5"
Length of plumbing: The spa blower is the round thing on the left of the Intermatic T104P timer, which is in the middle. That piping at the bottom the spa blower runs right toward the spa, which is about 10' away; the pool pump & filter are about 45' from there.

Current pump & filter set up:
Magnetek Century Centurian 3/4hp pool pump with C-1100 cartridge filter

Thanks again!

 

[e1836936]

What other info about the spa and it's requirements can I try to get?

 

[jblizzle]

Often spa pumps are even around 2HP (without a blower), but given that you have a small filter and all the water must pass through it, you likely should not go too big on the pump.

A 2-speed pump would likely be a good idea, run low for filtration and high when you want to use the spa ... that will save a good bit of electricity.
Likely a larger filter would be a good idea as well.

If you get the blower working, you may not need too large of a pump to have forceful jets.

How big is your pool? And we can try to suggest a filter size that may help improve the spa as well.

Please add your pool details and location as described HERE as it will help us help you.

 

[e1836936]

Thanks Jason, I actually was looking at a Jandy FloPro 1hp 2 Speed pool pump but reconsidered when I found that I needed to add some kind of relay switch or add another timer to go with my T104P.

No problem, I've added my pool details & location as described.

 

[jblizzle]

There are a few switch plates available that install on the back of the motor for $30.

Or get a Pentair Superflo which I know comes with the switch already installed. There is not usually a need for the speed change to be on a timer.

For a 15k gallon pool, consider at least a 220 sqft cartridge filter. Looks like your existing filter is less than half that, which will mean more frequent cleanings and higher restriction on higher flow rates.

 

[e1836936]

There are a few switch plates available that install on the back of the motor for $30.

Or get a Pentair Superflo which I know comes with the switch already installed. There is not usually a need for the speed change to be on a timer.

If I'm understanding...the speed change can be either automated via a different/additional timer or the speed change can be manual via a switch either added or already installed on pump. My other concern with the new 1hp 2-speed pump was that it had 2" pipe openings and I currently have 1.5" piping.

For a 15k gallon pool, consider at least a 220 sqft cartridge filter. Looks like your existing filter is less than half that, which will mean more frequent cleanings and higher restriction on higher flow rates.

I find myself cleaning it at least 1-2x week.

 

[jblizzle]

Your filter pressure is going up that quickly? That seems a little rare. With the size recommendations we make, usually they only need to be cleaned a couple times per year ... ASSUMING you do not have algae. Once algae enters the picture, you will be cleaning the filter a lot.

You are correct. The speed change can either be on a timer, or just done manually. In your case you could run on low most of the time and just kick up to high speed for the spa.

Do you plan on fixing the blower? If not, then you may want a little larger pump to have good jet action, but you would also likely need a larger filter to handle it.

Is your current motor 115 V or 230 V? Most 2-speed pumps seem to be 230V, but a few of the smaller ones are 115V. It does not really matter what the pump openings are as you can use fittings to change to the smaller pipe. Some of the smaller pumps (Superflo) come with fitting for 1.5" pipe.

If you are going to be replumbing any, it does not hurt to increase the pipe diameter where you can to increase flow rate.

 

[e1836936]

Your filter pressure is going up that quickly? That seems a little rare. With the size recommendations we make, usually they only need to be cleaned a couple times per year ... ASSUMING you do not have algae. Once algae enters the picture, you will be cleaning the filter a lot.

Pressure seems to run about here most days.
How do I know, if algae had entered the picture?

You are correct. The speed change can either be on a timer, or just done manually. In your case you could run on low most of the time and just kick up to high speed for the spa.

Automation is NICE! How about when using the Great White pool vac?

Do you plan on fixing the blower? If not, then you may want a little larger pump to have good jet action, but you would also likely need a larger filter to handle it.

If cost effective, it'd be nice.

Is your current motor 115 V or 230 V? Most 2-speed pumps seem to be 230V, but a few of the smaller ones are 115V. It does not really matter what the pump openings are as you can use fittings to change to the smaller pipe. Some of the smaller pumps (Superflo) come with fitting for 1.5" pipe.

If you are going to be re-plumbing any, it does not hurt to increase the pipe diameter where you can to increase flow rate.

Here's the label from the pump.
I'm not planning on re-plumbing, only if necessary. How would using a fitting to change to smaller pipes affect water flow?

 

[mas985]

The blower should really not make a difference when sizing a jet pump. Blowers only add air which doesn't have much momentum so it really doesn't add to the strength of the jets. Blowers simply compensate for the poor air duct designs that have too much restriction to work on their own. Some builders have claimed that they have successfully build spas with air ducts longer than 100' without a blower so it isn't necessary unless the design is poor. The main criteria for a spa pump, is the flow rate that the jets require.

 

[jblizzle]

What makes you think you need to clean every week? Does the pressure shoot up? That pressure seems so low it is basically not believable. Does it go to zero when the pump is off? Are you getting good flow into the pool?

Yes you would run high for the vacuum.

That motor can be either wired for either 115V or 230V ... so that does not help know what you current wiring is. Is it on a single or double breaker?

Smaller pipe and fittings raise the head loss and pressure and decrease the flow rate.

 

[e1836936]

Well, maybe I'm over doing the cleaning but it's seems very dirty when I do clean it. FWIW, I AM doing a lot of landscape & remodeling work around it so I'm sure that's added to it. I don't believe the pressure shoots up and yes, it goes to zero when it's turned off. I believe I'm getting good flow into the pool...The over flow spa appears to be flowing nicely and the 2 eyeballs flow pretty well also...but how do I confirm?

Although, I like the sound of automation, a manual switch sounds more appropriate, if I'm only switching to higher speed when using the spa & cleaner.

Hmmm?
If a smaller pipe and fittings raise the head loss, pressure and decrease the flow rate...
That doesn't sound good!

I'm not sure how the motor is wired but this what I've as far as electrical boxes outside for the pool:

 

[mas985]

If a smaller pipe and fittings raise the head loss, pressure and decrease the flow rate...
That doesn't sound good!

It all depends on your perspective and how you react to it.

Smaller pipe increases head loss which results in lower flow rates and lower energy consumption. However, the gallons pumped/watt-hr is lower too so technically the efficiency is lower. So if you increase run time to compensate for the lower flow rate, then the net energy use would go up. However, if you kept the same run time, then you would benefit with slightly lower energy use at the expense of lower amount of water filtered which may not be a bad trade off.

The opposite is true when you increase plumbing size. The flow rate increases, energy use increases but the gallons pumped per watt-hr also increases making the pump more efficient. However, to benefit from that increase in efficiency, you must reduce pump run time. If the pump run time is fixed because of other requirements, solar, SWG run time, etc, then you are actually better off with the more restrictive pumping.

 

[e1836936]

Thanks!
I apologize for the delay...

Like was said earlier..."If you are going to be re-plumbing any, it does not hurt to increase the pipe diameter where you can to increase flow rate."
So, I'll have to look into that.

What else can I let you know to help suggest the proper type & size pump & filter?

 

[e1836936]

Thanks!
AGAIN...I apologize for the delay...
What else can I let you know to help suggest the proper type & size pump and/or filter?

 

[jblizzle]

Didn't we already go through this? Here is the filter recommendations again.
For 15k pool minimums are:
220 sqft cartridge
23" sand filter
43 sqft DE filter

Still recommend 2 speed and the size depends on the how much water you want to move through the spa jets.

 

[e1836936]

Didn't we already go through this? Here is the filter recommendations again.
For 15k pool minimums are:
220 sqft cartridge
23" sand filter
43 sqft DE filter

My apologies, I didn't see where anyone mentioned sand or DE? It appears that cartridge filters larger than the 1750 require upto 4 cartridges, which seems costly moving forward come replacement time.

...the size depends on the how much water you want to move through the spa jets.

Do you plan on fixing the blower? If not, then you may want a little larger pump to have good jet action,...

The blower should really not make a difference when sizing a jet pump. Blowers only add air which doesn't have much momentum so it really doesn't add to the strength of the jets...

I'm kinda confused here about the pump size as related to the blower & spa jets??
Yes, "it'd be nice" (fixing the blower), "If cost effective" & I "want to use the spa to it's full potential.".
FWIW, make & model recommendations would be very helpful as well!
Thanks!

 

[mas985]

Cartridge filters have the lowest head loss of any of the filters and yes while the cartridges can be expensive to replace, if you maintain the filters properly you can get a good number of years out of them. I have just been through 8 years on mine and still without a tear.


But to size the pump properly, I would like to get some more information.

The pressure on the filter seems way too low so either the pressure gauge on the filter is broken or there is an issue with the pump impeller and/or suction lines. This could be part of the problem with the spa jets so I think some diagnostics are in order.

Also, was the pressure shown in spa mode or pool mode?

If you tap on the pressure gauge does it change?

Does the gauge go to zero when shut off?

Have you ever disassembled the pump to inspect the impeller/diffuser?

Do you know the size of the spa jet nozzles? (not the exterior fitting but deep inside the spa is a nozzle with a small opening)

 

[e1836936]

Cartridge filters have the lowest head loss of any of the filters and yes while the cartridges can be expensive to replace, if you maintain the filters properly you can get a good number of years out of them. I have just been through 8 years on mine and still without a tear.

Thanks!
I guess the question for me is....Is it worth the extra replacement cost to go from say the 1750 (one cartridge) to something like the 2020 (four cartridges)?

But to size the pump properly, I would like to get some more information.

The pressure on the filter seems way too low so either the pressure gauge on the filter is broken or there is an issue with the pump impeller and/or suction lines. This could be part of the problem with the spa jets so I think some diagnostics are in order.

Also, was the pressure shown in spa mode or pool mode?

If you tap on the pressure gauge does it change?

Does the gauge go to zero when shut off?

Have you ever disassembled the pump to inspect the impeller/diffuser?

Do you know the size of the spa jet nozzles? (not the exterior fitting but deep inside the spa is a nozzle with a small opening)

I'm not sure what mode it was in at the time of the picture BUT at that time, when I connected the auto vacuum cleaner into the skimmer, it was not getting much suction & hardly moving. Since then, I kept opening & closing valves until I got good suction in the vacuum...Again, I'm really not sure what "mode" it's in but I have good suction on the vacuum & that "sucker" (no pun intended) almost makes up the side walls...(It kinda pulls a Bo Jackson on the Royals...when he ran up the wall and back down again with out making it to the top) but it's moving much faster now AND I still have good flow from the spa . Today the pressure is hovering near 15...I haven't cleaned the filter in several weeks.

I'm also not sure about anything "deep inside the spa"...Only what I can see on the exterior.