This may be a dumb question, but why do you need a spa fill and spa jets. Why not loop back spa fill into the spa jets like most pools?
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- Thread starter Foosman
- Start date
The primary reason is to get a higher flow rate to the spa when the spa is spilling over into the pool. We have a 8' spa spill over and I'd like to be able to move 80GPM to have a nice sheet of water. We could have put in more jets, but I was worried it would result in weaker jets. Also, we are not using an air blower, to avoid the noise, so spillover mode would result in the spa bubbling...which I did not want. Finally, some TFP members pointed out that we can pre-heat the spa quicker without the aeration of the jets if we use the spa fill instead of the jets.
if we had a smaller spill over I would not have added a spa fill.
I know the Spillway flow was always your intention but with that kind of flow I would have opted for a dedicated pool suction to a waterfall pump (Pentair AFP-180 ) and dual 2" returns to the spa. You may struggle to get your desired look even if you do get 80gpm. That's a huge spillway.
The spa is not far from the pump, so the head loss is low...I'm not worried on the spa fill. The suction side is a little harder to figure with 2 skimmers and a drain and needing to balance these when running in normal circulation mode. I picked a cartridge filter due to the lower head loss.
I have a second pump for 2 bubblers and 2 water bowls, so I do have a straight pool suction line in play. I'll have to think about this as perhaps I should use a dedicated pump on the spillover and the VS pump for the bubblers/water bowls.
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Ahhh..... so you are using the spa jets with a Venturi instead of a blower so there is no way to turn off the bubbles?
That is a big spill over. That will look nice once you get it dialed in.
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I like the idea of a dedicated VS for water features. Especially if you you are changing what features are on. You could dial in each combination of features with valves and speed until it looks just right.
I plan on having 3 bubbles on a tanning ledge and two bubblers in scupper bowls. In addition, I have planned a rain curtain and some deck jets. Only some combinations can work together and look right, so I will figure out what speed looks good for each combination and that will be that.
Just my two cents.
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That's exactly my point... Your head loss is low but you'll be using a high head pump. I've seen them easily turn spas into whirl pools which will not be good for your Spillway appearance.
- May 23, 2015
- 24,694
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
I can corroborate from direct experience that you do not want a high head pump on a low head water feature. I have a 3HP single speed WhisperFlo pump on my waterfall (fed by a 2" pipe with about 50' of run). When it was first installed, it would rattle and cavitate like crazy. I had to install a shutoff valve on the waterfall pipe and do a lot of adjustments of the three-way splitter valve (the pump feeds the waterfall and an additional wall return) and the shutoff valve to create enough back pressure on the pump to quiet it down while simultaneously trying to optimize the flow out of the waterfall. It's basically a huge Rube-Goldberg setup whose primary function is to waste a lot of electricity.
Someday, when I get off my lazy rear end, I'll tear out the WhisperFlo and install the exact waterfall pump that Brian suggested above.
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I will be using an Intelliflo 2 VST so I can adjust the speed down. I'm attaching the curve below. My understanding is the rule of thumb for a sheer decent is 10GPM per foot, so I targeted 80GPM as the maximum. Since it's a spillover I think less than 80GPM would likely also look nice. I didn't pay too much attention to the hydraulics since I was thinking I could adjust the VST speed, but now I'm a little worried. If the return head loss is too high, my plumbing plan would allow me to divert some water to the jets in addition to the spa fill, but I don't think too high a head loss is going to be the issue. I could add a valve on the spa spill, but with the 2" pipe at 84GPM I'm already at 8ft/s. Sounds like I need an expert TFP-er to help me with the hydraulics calculation here!
- May 23, 2015
- 24,694
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Basically you have an open 2" pipe running from your IntelliFlo to the spa. That is a very low head plumbing line and it's similar to how my waterfall got plumbed. You're basically down around 20-30ft of TDH which means you're probably going to have to run the pump below the 2350RPM curve to keep it happy. The end points of the curves are basically where the pump stops operating efficiently and starts to cavitate because the water flow rate is too high. That's what happens in my waterfall - the 3HP Whisperflo runs full-tilt at 3450RPM and the unobstructed length of the 2" pipe doesn't provide sufficient head loss to keep the flow rate on the curve. So the flow rate spike to a point where the impeller starts to cavitate (and I know this is cavitation because it sounds like marbles rattling around in my wet-end when the pipe is fully opened). Cavitation can be very bad for the pump's internal parts (erosion) and wastes a lot of energy.
The waterfall pump that Brian cited is a nice option because it costs A LOT less than a variable speed pump and it is designed to move lots of water at high flow rate under lower pressure. So, even though it is a single speed pump, it is more efficiently moving the water than a similar sized pool pump.
I bet with the VSP you'll be able to find a speed that keeps the pump from cavitating. The only problem is, will that speed get you the flow rate you need to make the spillway look good? If I had to hazard a guess, I think you'll be right on the edge but you should be ok...
The waterfall pump that Brian cited is a nice option because it costs A LOT less than a variable speed pump and it is designed to move lots of water at high flow rate under lower pressure. So, even though it is a single speed pump, it is more efficiently moving the water than a similar sized pool pump.
I bet with the VSP you'll be able to find a speed that keeps the pump from cavitating. The only problem is, will that speed get you the flow rate you need to make the spillway look good? If I had to hazard a guess, I think you'll be right on the edge but you should be ok...
The 10gpm/ft formula is for actual sheer descents that are manufactured to direct the water for that type of appearance. In the case of your Spillway, I don't see 80 GPM giving you the arc you are after.
My Spillway design is much different than yours but I have about 5' total feet that an Intelliflo XF with 3" plumbing can not provide enough water to project outward.
My Spillway design is much different than yours but I have about 5' total feet that an Intelliflo XF with 3" plumbing can not provide enough water to project outward.
Brian,
I see your point now...that 80 GPM is not nearly enough. I agree, if I need more than 80 GPM then it would have been better to run additional plumbing and use a water feature pump. I recall seeing a similar spa spillover on here with a ~7' spill over and no special plumbing and it looked good. I'll do some searching for this pool If the flow is too low then I'll play around with sending it out the jets and spa fill which will get me above 80 GPM. I have 2 skimmers that are 2" lines and a 2" drain line, so I can likely get more than 80 GPM on the suction side. I'm just not sure the head loss is where it needs to be in this case, but I might be able to push this to 110-120 GPM with the VS pump.
- May 3, 2007
- 17,387
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
When in this spillover mode, will the water be traveling through the filter and heater too? If so, that is likely to add quite a bit of head loss.
Also, is the 2" pipe into the spa actually going to be open without any wall fixture or eyeball?
I can estimate the maximum flow rate if you can give me some more details about the plumbing setup, run lengths, fittings (if you know them).
Also, is the 2" pipe into the spa actually going to be open without any wall fixture or eyeball?
I can estimate the maximum flow rate if you can give me some more details about the plumbing setup, run lengths, fittings (if you know them).
Yes, when in spillover the suction will be through the usual circulation path: filter, SWG, heater. I'm not sure what the plan is for the spa fill fitting...it's in the spa wall so will need something. I would definitely appreciate the calculation for the scenario returning to both the spa fill and jet simultaneously.
Filter: Pentair CC520
Heater: Raypak 406
SWG: IC60 SWG
Return side plumbing:
Spa jets: 44' total: 2.5" PVC for 37' then 2" PVC for 7'. 6 Jets in a 2" loop. 4 90's. 2 Jandy 3-way valves in path.
Spa fill: 46', 2" PVC, 4 90's. 2 Jandy 3-way valves in path + 1 Jandy check valve
Suction side:
Skimmer 1: 47', 2" PVC, 5 90's, 1 Jandy 2-way valve + 1 Jandy 3-way valve
Skimmer 2: 90', 2" PVC, 6 90's, 1 Jandy 2-way valve + 1 Jandy 3-way valve
Pool drain: 60', 2" PVC, 8 90's, 1 Jandy 2-way valve + 1 Jandy 3-way valve
Thanks!
- May 3, 2007
- 17,387
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
This is a rough estimate but I get about 110 GPM @ 79' of head @ 3450 RPM. If you had two 2" return pipes that would increase the flow rate to 120 GPM.
Thanks Mark. This gives me another option to try when I fire up the pool. I think the biggest downside of returning through both the spa fill and jets is the aeration of the jets...I guess I can plan to keep the manual air intakes closed when not using the spa.
- May 3, 2007
- 17,387
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
When I said two return paths, I was not referring to the spa jets. I was referring to an identical path to the spa return. Spa jets have a lot of head loss so that path will really not help much. A couple GPM at most.
You can always put an automated valve on the air line if you don't want the aeration
So this is using just the spa fill return for the return: "Spa fill: 46', 2" PVC, 4 90's. 2 Jandy 3-way valves in path + 1 Jandy check valve"?
I guess my concern would be the velocity, since it's only a 2" pipe...seems the pressure would be really high and potentially hard on the plumbing?
- May 3, 2007
- 17,387
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
The 110 GPM was just for the single return. Someone speculated on having a second identical return which is why I gave the 120 GPM number.
But return side velocity is far less important than suction side velocity due to risk of entrapment. High velocity just means high head loss which is what you will have. But other than that, there is really no issue. The return side has filtered water so very little abrasion.
But return side velocity is far less important than suction side velocity due to risk of entrapment. High velocity just means high head loss which is what you will have. But other than that, there is really no issue. The return side has filtered water so very little abrasion.