Pump Replacement on Hayward Tristar

Thanks for the reply!

I'm a bit confused though. Why the recommendation to upgrade so much on the pump? Original is 1 THP and I think was appropriately sized for the pool and filter. That's why I was looking at the 1.3 THP VS motor. Of course I'm planning to run this at lower speed for longer periods, but seems a good match when I need to run full power. What's the benefit of jumping to a 2.25 THP motor (and impeller)? It seems I'd never want to run that at full power with my little 84 GPM filter.

Just to provide an update on this: I got the new motor installed, and upgraded the impeller. I went with the 1.3 HP VGreen with SPX3210C impeller. I'm very happy with the results. Pump is way quieter at full speed than the old one (with obviously blown bearings). I'm currently running constant at 1725 RPM and it's extremely quiet with plenty of flow. I'll shortly play around with going down even further.

One drawback, and a possible reason to limit the upsizing you guys recommend: when running at full speed (as this pump does when priming for three minutes at startup), it pulls more than my skimmer can handle and will suck air. Part of that is because I have an overflow hole in the side of my skimmer that keeps the pool level from getting too high. I believe that hole is a bit low, so I'm going to put a small elbow on that to raise the level a bit. I also need to check that the weir is opening all the way. I guess if I went any bigger, this would be even more of a problem. I can set this thing to not do the full-speed prime if needed, so it's not a huge concern. I'm planning for 24x7 running, so will rarely do startup cycle anyway.

Oh, and based on advice here, I added a current-sensing relay to power the SWG. It works like a champ all the way down to 1K RPM. Coincidentally, my electronic timer decided to croak during the downtime while I was waiting for the pump to arrive, so it's a good thing this whole setup made that useless anyway!

Thanks for the advice here and all the great info in the archives!

Heater is a Hayward heat pump, always bypassed if not in use, and rarely used. I'll get the model and post up some pics. Thanks for the advice on the speed setting. Lowest it'll go is 1K. I think I ran it at 1100 during my initial fiddling and the SWG was active. That mode doesn't have a prime setting and may be where I land, and just manually boost whenever the heater is engaged. How does one determine the flow required for a heater?

Now for a follow-up. I filled the pool, actually a bit above the drain hole because I filled it while the pump was running, which pulls the water level down in the skimmer. If I shut the pump off, the level is just above the overflow drain. Running at this level, the full-speed prime runs fine with no air pulled through the skimmer. I'm going to definitely put a small extension on that overflow. I'm still running at 1725 because I've been more focused on getting all the pool math dialed in for the season. I'll drop speed lower soon.

As for the heater, I haven't run it yet with the new motor. I did check the label, and it says flow should be 30 - 75 GPM. Now I just have to figure out how to calculate my flow rates. I've attached a pic of my pad, all plumbing is 2". Just going by gut feel of the return jet turbulence on the water surface, this new motor at 1725rpm with the bigger impeller seems to be roughly the same as the old single-speed, but that's not very scientific. As little as I run the heater, I'll probably just boost the pump speed to at least 1725 to be safe.

Thanks for all the support!