Pressure and Flow issues

[DougS]

Hi all,
We just remodeled our in ground pool - 28,000 gallon pool with 18" raised spa with 32" spill wall into the pool. Spa has 6 jets (upgraded from 4).

Equipment:

• Pentair Intelliflow VS pump
• Pentair Clean & Clear Plus 320 filter
• Pentair Mastertemp 250 heater
• Solar heating just added

Problem: Raised spa doesn't spill over into pool unless I divert most (nearly all) of the return water to the spa and turn up the pump to almost maximum speed.

When we remodeled, the spa was raised about 18 inches off the ground and we added 2 spa jets. Also, we completely re-plumbed, so there are many more 90-degree angles in the plumbing. Also, they added 2 pool return ports.

When I sum it all up, there just seems to be not enough pressure getting to the spa to force the water to spill over.

I've wracked my brain and it seem that there are a few ways to solve this, but want help from experts:
1) Add flow restrictors to the pool returns (because the return water is taking the least-resistance path).
2) Redirect more return water to the spa (but I don't want to starve out the pool sweep which depends on pool return water. So I cannot go too far)
3) Add speed to the pump. But of course, the whole reason for variable speed is to save electricity, so I want this to work on low RPM settings (I'm hoping it will work at 2200 RPM or or less). Is that a pipe dream?
4) Get a bigger filter (420 instead of 320). My thinking is that with more surface area, the filters won't get dirty as quickly, so the pressure won't build up and rob the system of flow.

I haven't even started up the solar for summer yet, so I wanted to get this all working well before complicating it with the solar.

Any suggestions?

 

[chiefwej]

You might try changing the diameter of the pool return fittings. That way you will still have decent circulation for your skimmers, but it should increase the available flow for the spa.

 

[Jimrahbe]

Doug,

I don't have a spa, so you can take this for what it is worth. Seems to me even the smallest pump will cause your spa to spill over as long at more water is going in that coming out. Seems like the problem is the spa draining faster than it should. Is there some valve that selects between spill over and not?

JasonLion said this on 2-19-2014... "There are various modes, each of which uses different valve settings. In pool only mode you want 100% of both suction and return to the pool. In spa mode you want 100% of both suction and return to the spa. In spill-over mode you want 100% of suction from the pool and the return should be adjusted to go to both the pool and spa at the lowest flow to the spa possible that still makes the spill-over look good. Typically you run in spill-over mode for one hour a day, pool mode for the rest of the daily cycle, and spa mode when you are using the spa. However, some setups don't use all three modes, or vary the pool/spill-over relative times."

You might want to look at your valve settings..

Jim R.

 

[DougS]

Thanks Chiefwej,

I did add flow restrictors to the pool return fittings. That helped some, but not enough. I'm still dialing in the settings on the valves to have a mix of return to pool AND spa for the spill over to work. But I'm also working on getting better pressure overall. Just replaced the filter cartridges, so I'm testing that now. Also, the Pentair 320 stem (in the middle of the filter) might need replacing with a wider stem. I'm calling Pentair to discuss this because when I ordered a replacement screen, it had a bigger diameter than the original one. So I'm thinking they improved on the stem to help with pressure issues.

 

[DougS]

Thanks Jim,

I think you're right. I will have to use three modes (Pool only, Spa Spill with mixed return settings, and Spa only). But I'm still struggling with the overall low pressure. Just replaced the cartridges, so trying that. Also, the stem and screen in the very center is very narrow, so I'm thinking that may be it.

But another possibility here is that when we remodeled, we added several (5-10) 90-degree angles to the plumbing as well as 2 more spa jets. Maybe the pluming is causing too much overall "head" pressure loss. This article explains it: http://www.troublefreepool.com/threads/830-Hydraulics-101-Have-you-lost-your-head

That would mean replacing the 90-degree fittings with long-sweep 90s. That would be a big project to replace them, but it may be needed. This article says it improves pressure by 12% - http://www.pondtrademag.com/do-different-pvc-fittings-really-make-a-difference-in-water-flow/

Doug,

I don't have a spa, so you can take this for what it is worth. Seems to me even the smallest pump will cause your spa to spill over as long at more water is going in that coming out. Seems like the problem is the spa draining faster than it should. Is there some valve that selects between spill over and not?

JasonLion said this on 2-19-2014... "There are various modes, each of which uses different valve settings. In pool only mode you want 100% of both suction and return to the pool. In spa mode you want 100% of both suction and return to the spa. In spill-over mode you want 100% of suction from the pool and the return should be adjusted to go to both the pool and spa at the lowest flow to the spa possible that still makes the spill-over look good. Typically you run in spill-over mode for one hour a day, pool mode for the rest of the daily cycle, and spa mode when you are using the spa. However, some setups don't use all three modes, or vary the pool/spill-over relative times."

You might want to look at your valve settings..

Jim R.