Replacing 2hp motor with 3hp. Need advice

[optimus310]

Hey Guys,
I'm new to the forum and new to owning a pool. Sorry if this has been answered before, but I can't find the information I need. I recently bought a house with a 15K gallon in-ground pool. The pump that came with the pool was a Pentair Challenger 2HP which had been really loud since I moved in. Since the home was sold as is I didn't get the option to have them replace the motor. I recently came across a good deal on a Whisperflo 3HP (used) which runs very quiet and it’s in very good shape. Now I know that a 3HP motor is over killed for the size of the pool, but I guess I couldn’t pass on the deal. My concern now is if the 3hp motor can potentially cause problems to internal or external PVC piping.

The inlets that come from the ground to the 3way valve for skimmer and cleaning are all 2in.
I only have 3 side jets, a cleaning vacuum line and a skimmer.
No spa or anything else that would need that much more power.

The sand filter with the new pump is reading 18PSI, but I haven't backwash in about 2 weeks. I can’t backwash it at the moment due to a cracked pipe which I will fix this coming weekend.

Thanks for your input.

 

[bobodaclown]

Hello,
It will cost more to run in the long run, but that being said it's working. It shouldn't cause problems. The impeller is what moves the water. The impeller is matched to the motor. It's normally ok to go up in size on the motor but not down. Think of putting a V-8 motor in a small vehicle, over kill. But it you put a small 4 cylinder in to a large vehicle you'll destroy the motor. Kinda the same theory. Most electric single speed pool motors run at 3450 rpm. How much water it moves depends on the size of the impeller and restrictions.
Bigger impeller and more restrictions needs a bigger motor. Smaller impeller, less restrictions less motor needed.
Hope that makes sense.
Bob

 

[mas985]

So are you putting the larger motor on the old Challenger pump? If so, that is fine.

 

[JasonLion]

Welcome to TFP!

Assuming you replaced the entire pump with a 3 HP pump, it is certainly going to use significantly more electricity than a smaller pump would. It will also put more strain on the filter. You don't say what size your filter is, so I can't tell if the pump is oversized for the filter or not. You run some risk of causing channeling in the filter.

Your original pump was already significantly too large. Since you don't have a spa or other water features the correct pump for that pool would be a 1/2 HP or 3/4 HP pump.

 

[optimus310]

Thanks for the feedback guys, and sorry for the confusion. I did replace the entire pump not just the motor.

JasonLion: I'm not sure on the size of the filter right now since I'm a work, but if I had to guess its a Hayward 36 inch. I will double check that later today.

 

[optimus310]

So after looking at my filter last night looks like its the following model
Hayward Pro-Series S244S
http://www.hayward-pool.com/prd/In-Grou ... 5516_I.htm

Effective Filtration Area: 3.14ft
Design Flow Rate: 62 GPM
Turnover:
8hours 29,760 Gallons
10hours 37,200 Gallons
50 PSI Max


so all in all I think the filter should be able to handle the load. I backwashed it for about 2 minutes last night and dropped the PSI from 18 to 15. Other than using more electricity do you guys see any other potential problems like PVC not handling the load, filter blowing up or anything?

Thank you.

 

[jblizzle]

What size breaker is feeding the pump? Looks like a 2HP Whisperflo could be ~11amps while the 3HP is ~15amps. So, if it is fed by a 15amp service (14AWG wire), that could be a problem as well.

I have a feeling the extra electrical costs of running the 3HP are going to quickly become more than you would have spent for a 1HP which would likely have been plenty of flow for your pool.

 

[optimus310]

It has a dedicated 20amp breaker and it runs on 208-230v. I guess I will keep an eye on electric bill and perhaps replace soon if it goes over the top.

 

[mas985]

so all in all I think the filter should be able to handle the load.

huh? A 3 HP pump will probably well exceed 62 GPM so no, the filter won't handle the load. Dirt will most likely blow past the filter and you might even break a lateral or two.