Upgraded to VSP - now can't run below 2000 RPM

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zamazing

Well-known member
Jul 18, 2015
130
Bergen County, NJ
I recently upgraded my filter pump from a single speed 1.5 HP to a Hayward Tristar VS. Unfortunately, I cannot run the pump below 2000 RPM because I get a "No Flow" alarm on my panel which automatically shuts down the pump as well as the SWG. The main reason for this is that my pool requires two T-15 SWG cells and the cells are plumbed in parallel (see photos below). As a result only half of the actual water flow is detected by each of the flow switches.

I am considering removing the two flow switches from their current location and just using one flow switch either before or after the point where the water splits. I figure I can then use a basic phone jack splitter (see photo) to connect the single flow switch to both my Omnilogic and Aquarite Panels. Before I go ahead with this, I want to see if anyone sees any safety (or other) issues with this approach.

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Given that you do not have valves that could isolate one or the other SWG, I think it might be ok to just have a single flow switch, not exactly sure how that would be wired to both controllers though.

There is some concern that the lower flow through each SWG could result in some gas build-up. To help with that, I would rotate the cells down 180 degrees so the gas can not build up in the cells (this is recommended for low flow rate applications by Hayward).

I think another option might be to run the cells in series with only 1 flow switch. Although admittedly I am not sure if that is recommended or not or if there is a reason not to do so.
 
You are splitting the flow between two SWGs so technically, you need twice the minimum flow rate to be safe. If you move just the flow switch you will be operating below minimum requirements which I wouldn't would be a wise thing to do. A series installation of the cells would be a better solution.
 
jblizzle said:
I think another option might be to run the cells in series with only 1 flow switch. Although admittedly I am not sure if that is recommended or not or if there is a reason not to do so.
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mas985 said:
You are splitting the flow between two SWGs so technically, you need twice the minimum flow rate to be safe. If you move just the flow switch you will be operating below minimum requirements which I wouldn't would be a wise thing to do. A series installation of the cells would be a better solution.
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Thanks for the advice guys. I agree that installing the SWG's in series makes the most sense. I will try to contact Hayward to see whether they see any long-term issues with doing so. Clearly, the second SWG in line is going to be exposed to highly-chlorinated water on a regular basis. That can be controlled to some extent by setting the percentage on the first SWG to say 20%, and putting the main burden of chlorine production on the second SWG, and then switching them around every couple of months.

On a related note, I know that TFP recommends shutting off your SWG when doing a SLAM. Does the reason behind that have anything to do with not wanting to expose the SWG cell to highly-chlorinated water?
 
The SWGs do not really make "highly chlorinated water".

The reason for that recommendation is so that you have a better feel for the progress of the SLAM without the SWG adding chlorine, nothing to do with the elevated FC levels. If you are not able to be around much, you can certainly use the SWG to supplement the FC. Just adds a little more wear and tear on the cells who will only generate X amount of chlorine in their life.
 
zamazing said:
Thanks for the advice guys. I agree that installing the SWG's in series makes the most sense. I will try to contact Hayward to see whether they see any long-term issues with doing so. Clearly, the second SWG in line is going to be exposed to highly-chlorinated water on a regular basis. That can be controlled to some extent by setting the percentage on the first SWG to say 20%, and putting the main burden of chlorine production on the second SWG, and then switching them around every couple of months.

On a related note, I know that TFP recommends shutting off your SWG when doing a SLAM. Does the reason behind that have anything to do with not wanting to expose the SWG cell to highly-chlorinated water?
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Sounds like a good plan.

I'm not aware of any issues that SLAM level FC would cause to an SWG.

It's a grey area on recommending SWG off during SLAM. Yes, it must be off when performing the OCLT. However, it can be helpful in maintaining some FC levels if the owner is not able to dose frequently, such as when they are at work, etc., to keep the FC levels closer to shock level for longer periods without manual dosing. It's an owner comfort level and expertise issue whether or not to use the SWG during a SLAM. Sometimes it's best to simplify things and only have one source of FC being bleach during a SLAM, especially for someone new to self-testing and managing their own pool.
 
The flow switch is a safety feature to ensure the cell has enough flow. I don't think I'd rely on one prior to the Tee, or even a single one from just one side. You could end up with the switch saying there is enough flow, yet neither cell "really" has enough. Cells in series makes sense though if Hayward says it's ok.

I'm confused though, why is your pump getting turned off? I have my SWG wired so I generate a false no-flow condition when I don't want it to run but it doesn't shut off my pump.

If you do want a single control source and still ensure each cell still has enough flow for safety I would re-wire the switch wires themselves. Each is a simple open/closed circuit so you could wire one side to go between the two switches and the other wire from each going to the connector creating one larger circuit. BOTH flow switches would then have to have enough flow for anything to turn on. If either is low it will show a no-flow condition.

It seems like what you have should work well though, other than the stopping the pump part. If 2000 rpm isn't enough for both SWG to work then 2000 rpm isn't enough.
 
The T-15 Cell produces 1.45 lbs/24 hours or 0.001 lbs/min and if the pump is pushing only 20 GPM at 1000 RPM, the rise in FC is only 6 ppm.
 
NeedMoreSun said:
I'm confused though, why is your pump getting turned off? I have my SWG wired so I generate a false no-flow condition when I don't want it to run but it doesn't shut off my pump.
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With the Omnilogic panel, you can create a variety of Interlocks between different equipment. For example, you can setup an interlock between your filter pump and cleaner pump so that the cleaner pump will not turn on unless the filter pump is on. There is a default interlock between the flow sensor and filter pump when you have an SWG installed. A No flow condition effectively prevents the SWG from being activated and also eventually shuts down the filter pump so that it doesn't run dry.
 

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I looked into this further and it's not exactly an interlock between the flow sensor and the filter pump but a feature called Flow Monitoring that can be enabled for any given pump. Here's the clip from the manual:

Flow Monitoring Enabled? Requires use of a Hayward flow switch. This feature will help protect the filter pump from damage due to no flow. When Yes is selected, the OmniLogic will monitor the state of water flow when the filter pump is on. If no flow is detected for more than 20 minutes, the OmniLogic will shut down the pool pump and will indicate an error. The error will be cleared the next time the pump is turned on.​

I suppose I can disable this feature to run the pumps below 2000 RPM for filtration, and then crank the RPM up above 2000 for a couple of hours for chlorination. I'm not so keen about losing this safety feature though...
 
Yeah, and being split is causing it even when there is plenty of total flow the pump would be worried about. Go with a single flow switch and it would allow the SWG to be on when there isn't really enough flow. Too bad they couldn't specify which flow switch for what and add one :)

What about your pump itself? Is it able to sense loss of prime, aka no flow, and pause or shut itself off? If so it's a redundant setting anyway at the controller level?
 
I think I may have come up with a solution that retains the safety feature.

I can leave the two existing flow sensors as they are plumbed and use them to regulate chlorine production. One flow sensor is wired to the Omnilogic panel and the second to an Aquarite panel. It turns out that the Omnilogic has a second flow sensor input. The plan is to add a third flow sensor before the split and wire that to the second input on the panel. Then I can enable flow monitoring on the pump but tie it to this new sensor which will presumably trigger at half the RPM of the other two.

Does this make sense?


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But then the SWGs will still not generate chlorine below 2000 RPM. Why bother even running the pump at that point.
 
I'm not sure because of the Flow Monitoring feature.

Maybe I need to re-think why I need to operate below 2000 RPM. Outside of efficiency, is there any other reason for operating at 1000 RPM? I assume running the pump for 8 hours at 1000 moves the same amount of water as running the pump for 4 hours at 2000 RPM.


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Yes the turnover is the same but so what. If your skimmers don't work at 1000 rpm, it is wasted runtime.

Before making ANY plumbing decisions, you should really get a handle on what works (RPM) for your setup and what doesn't.
 

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