Looking to replace my old single speed motor with a variable speed as my pump seems to still be in great condition. From what I am finding looking at retrofit variable speed motors, I have a choice of a 1.3 or 1.65HP motor. As far as I understand, my current pump is a 1HP. Does it makes sense to upsize to the 1.65HP and upgrade the impeller and related parts to a 1.5HP to run at a lower RPM? Or am I better off leaving the 1HP internals? For reference all of my plumbing is 1.5" on suction and return side. Single main drain and 2 skimmers on suction side, 3 return jets on return side. Thank you all in advance for the insight.
Do I Need To Change Impeller with Variable Speed Motor Swap?
- Thread starter kevtheo1191
- Start date
- May 3, 2014
- 62,616
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Welcome to the forum!
Post a picture of your PUMP label. We need to know the brand/model and any other identifying information.
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool
Post a picture of your PUMP label. We need to know the brand/model and any other identifying information.
I suggest you read through Pool Care Basics - Trouble Free Pool and even look at a few of our videos TFP-TV - Trouble Free Pool
Have looked all that over a few times, dug through old posts and couldn't find an answer specific enough to make a judgement call. I will have to look again tonight but I do have this label from the motor handy, has the pump model on it.
- May 3, 2014
- 62,616
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Your current motor is 1.25 hp. You can use the 1.65 hp motor if that is the THP. Is it variable speed?
Yes. Would it be recommended to get the 1.5HP pump internals to upgrade from the 1HP pump internals to better match the new motor and run at a lower rpm? or is a 1.5HP pump a waste on 1.5" piping?
www.inyopools.com
Pentair Challenger (CF Series) VS Motor Upgrade Kit - 1.65HP - INYOPools.com
Pentair Challenger (CF Series) VS Motor Upgrade Kit 1.65HP
www.inyopools.com
- May 3, 2014
- 62,616
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
- May 3, 2007
- 18,052
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
It does make sense to upgrade to a higher HP if you really want to keep that wet end. But the challenger wet ends are not exactly the best design. I would probably be more incline to do a full replacement.
Have you considered some of the lower end VS pumps from Calimar or Black & Decker?
I haven't no. Mainly looked at Pentair and Circupool for full replacements. This just seemed like a nice middle ground to get away from the single speed and not have to cut up all my PVC again. Most of my equipment is older but in good shape because its in a shed. But if the technology of the pumps has improved enough as well as the motors then maybe I need to reconsider.
Side question: Is the 1.5" PVC too much of a restriction as far as a 1.5HP pump is concerned vs sticking to a 1HP (matching motor if I go new obviously). Read multiple posts that say go bigger and run at a lower RPM. My sand filter is huge so I have plenty of headroom for GPM, need to do the calculation of what the current setup is putting out.
Side question: Is the 1.5" PVC too much of a restriction as far as a 1.5HP pump is concerned vs sticking to a 1HP (matching motor if I go new obviously). Read multiple posts that say go bigger and run at a lower RPM. My sand filter is huge so I have plenty of headroom for GPM, need to do the calculation of what the current setup is putting out.
- May 3, 2007
- 18,052
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
If you are running at lower RPM, the pump behaves like a lower THP pump. The impeller hydraulic HP (HHP) delivered to the water is dependent on RPM^3. So 1/2 the RPM, is 1/8th the HHP.
But even running the pump at full speed with 1.5" plumbing, while inefficient, is usually not a big issue. In some ways, running at high RPM on small plumbing is self-correcting in that the pump has lower flow rates with more restriction. But in general, you will want to keep velocity below 8 ft/sec or ~50 GPM.
However, for maximum energy savings, the objective is to set the RPM as low as possible while still accomplishing the task at hand (e.g. skimming, SWG, heater, etc.).
But even running the pump at full speed with 1.5" plumbing, while inefficient, is usually not a big issue. In some ways, running at high RPM on small plumbing is self-correcting in that the pump has lower flow rates with more restriction. But in general, you will want to keep velocity below 8 ft/sec or ~50 GPM.
However, for maximum energy savings, the objective is to set the RPM as low as possible while still accomplishing the task at hand (e.g. skimming, SWG, heater, etc.).
That all makes sense. Yeah the idea is not to just throw money away and figure out the lowest RPM I can run at, sounds like a better unit where you have more control over RPM may be the smart decision than predetermined points. I've seen that SWG can be pretty picky about minimum flow rate depending on the brand. Guess its time to put this mechanical engineering degree back to work and do some hydraulics math
