Pump Replacement on Hayward Tristar

[racingiron]

Hi all, first post, but longtime lurker. Really appreciate this resource and thanks in advance for advice on this post.

I’m replacing the pump on my 11 year old Hayward Tristar SP3205EE. Original pump has bad bearings and when I pulled it off yesterday to inspect, I found it very crusty overall and can’t even get it fully open for some reason. It’s a single speed 1/2 HP (0.99 THP) Century. Planned replacement is V-Green EVO VS (1.3 HP) that I’ll run at a slower speed for my 12k gal with just cartridge filter and SWG (and rarely used heater).

I’ll get a “go-kit” and probably new seal plate too. Just wondering if I should replace anything else as a matter of course? Does anyone know if the 48Y V-Green comes with a spacer for 56Y install? Will the original impeller be adequate with the new motor? Inyo lists this impeller as “1/2 - 3/4 HP” and “0.75 THP” which is a bit confusing since it’s on a 1 THP unit.

 

[mas985]

A 1/2 label HP having 1 THP motor rating is not uncommon. THP motor ratings for single speed and two speed pump are usually always higher than the label HP. Just part of the industry confusion about motor ratings and marketing tactics. DOE regulations has now changed that so all motors are now labeled with only THP.

But I would recommend upsizing the impeller and the VS motor. The reason is that smaller impellers are less efficient and nosier at same flow rates as larger impellers. Plus are easier to clog up.

For example, if you go with a VGREEN EVQ 225, you can then use SPX3215C impeller as a match for the THP.

However, with VGREEN you can actually use even a larger impeller than what the motor can support and the motor will automatically derate (i.e. run at lower RPM) to accommodate what ever impeller you decide to use. It is a great feature.

 

[racingiron]

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.

 

[PoolStored]

By upgrading, the higher HP motor can move the same water with less electricity. It will save you money on electricity.
I doubt, even if you upgrade, that the pump will put out 85 GPM at full speed.

 

[racingiron]

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!

 

[PoolStored]

If you are not going to use the heater, then clean the filters, then turn the pump down until the SWG flow switch turns it off. Then add 200 RPM for a dirty filter and that is the lowest you can and should run if you want to use the SWG.
If you are going to use the heater, it is going to require flow. Depending on the model, you may have to run 2200 RPM or so to get enough flow to not damage the heater.
Is your heater in the loop? What is the heater model#? Is it bypassed?
Post a few pictures of your equipment pad.

 

[racingiron]

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?

 

[PoolStored]

How does one determine the flow required for a heater?

The manual.

 

[1poolman1]

How does one determine the flow required for a heater?

Along with Pool Stored advice, you just clean the filter, find a speed that allows the heater to work and add 200 or so rpm for a dirty filter and you are good. You don't really get to adjust an EVO to that degree, so just find a speed that works, and one that doesn't. Use the one that does. Every pool is different.

 

[racingiron]

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!