Should I change my Pump Impeller or buy a Variable Speed Pump?

[Dead Beaver Ranch]

Here's my setup:
~20,000 Gal Inground pool with Vinyl liner
Sand filter Hayward S244T
Pentair Rainbow 320 Automatic Chlorine (used very rarely)
Hayward booster pump for Polaris 280 pressure side cleaner
Hayward Heatpro Heatpump
All pipe is 1.5"

As best I can tell the pump is a Hayward Pump Model #SP2607X10. I can't be certain as the label is missing and the motor is not the original motor. The current motor is an A.O. Smith 1.0 HP/1.0 SF. I calculate I have less than a 20' head if I average the line coming from the skimmer and the line coming from the bottom drain. If so, the specs for the pump shows 85 GPM for a 20' head. Based on my other equipment it looks like what I really need is about 45 GPM.

If this is all correct it appears to me that I have WAY more pump than I need. I have read here that I can benefit from changing out the impeller. The pump motor is new while the pump itself is older but still has some good life left in it. I am getting sand blowing out onto the steps of the pool. I replaced all the internal components in the sand filter but this has not corrected the problem. I'm thinking the real issue is the pump is oversized. I am assuming it currently has 1 hp rated impeller (SPX2610C). I am thinking I want to change the impeller to solve my problem and save on electricity. It also looks like the impeller is the only part I would need to replace as the diffuser would stay the same. I watched very closely when the service man replaced the pump motor so I am pretty confident I can handle the task of changing the impeller.

My questions is should I replace the impeller or purchase a different (variable speed) pump?
If the recommendation is that I replace the impeller, which one should I use (SPX2607C or SPX2605C)?

Thanks for your help. This site has been very helpful to this first time pool owner.

[mas985]

I calculate I have less than a 20' head if I average the line coming from the skimmer and the line coming from the bottom drain. If so, the specs for the pump shows 85 GPM for a 20' head.
Exactly how did you calculate that? Hint, calculating head loss is not trivial and it isn't just the length of pipe. I doubt it would be that low. I can estimate it for you but I will need the following information

What is your current filter pressure?

How high is the filter gauge relative to the pool water level?

Number and length of suction lines from the pool to the pump?


I doubt the pump is over sized, it is one of the smallest pumps on the market. If you have sand blowing into the pool, it could be broken lateral. That is the most common issue with sand filters.

As for a VS, it usually isn't worth the extra cost unless you have very high electrical rates.

[Dead Beaver Ranch]

Answers:

What is your current filter pressure?
-Current pressure is 18 lbs. When it's clean the pressure is 14 lbs.

How high is the filter gauge relative to the pool water level?
-50"

Number and length of suction lines from the pool to the pump?
-Two lines which come together as one somewhere underground: from skimmer to pump is 12.5' and from drain to pump is 22'


I doubt the pump is over sized, it is one of the smallest pumps on the market. If you have sand blowing into the pool, it could be broken lateral. That is the most common issue with sand filters.

-I have completely replaced all the components to sand filter, so I have ruled out a problem lateral. The only thing not new is the tank.

Thanks, DBR

[mas985]

The pressure seems a bit high for that setup so that might have something to do with it. Does the pressure gauge go to zero when the pump shuts off?

Assuming the gauge is correct, the pump's operating point is around 42 GPM @ 54' of head. The 244T is a 3.1 sq-ft filter and it has a design flow rate of 62 GPM so the flow rate from the pump is fine. I would focus on the filter. Given the pressure, something is still not right.

[Dead Beaver Ranch]

Yes, the gauge goes to zero when the pump is shut off. I replaced the pressure gauge when I rebuilt the filter. Is it possible that the wet end has the impeller for a 1.5 hp pump?

Are you saying my setup has a 54' head?

Thanks

[mas985]

Is it possible that the wet end has the impeller for a 1.5 hp pump? Not unless the motor was up sized as well. Up sizing the impeller without up sizing the motor will overload the motor and trip the thermal limiter switch.




Are you saying my setup has a 54' head?
Yes, that is my best estimate based upon the filter pressure and the suction side plumbing layout.

[Dead Beaver Ranch]

So it looks like I should leave well enough alone as far as the pump goes. Is the pressure I am seeing at my filter what you would expect? If not, is it higher or lower than you would expect? Thanks again.

[mas985]

As I posted earlier, the pressure seems to be a bit high which means that there is more head loss in the return plumbing than would normally be expected for that setup. It could be the filter or anything after the filter.

[skeeter_ca]

mas,

Would you recommend him tapping into the system in a few different points to determine where the back pressure is? Maybe one between the filter and heater and then one after the heater.

skeeter

[mas985]

That is a bit invasive and could cause other issues. However, a picture of the pad equipment might be useful to narrow it down some. Check valves, filters and backwash valves have all been know to cause problems with high pressure. Not to mention an incorrect valve setting. :o