Pentair VS Issue/Question

[batterfierd]

Hello, I recently installed a pentair VS pump. After a bunch of tweaking, it seemed to be working pretty well. I have an Intelliflo spreadsheet that shows the relationship between wattage and flow, and all seemed well.

But not I have an issue. I took various wattage readings during my initial installation and saved the information. Two months into it, and the wattage/water flow seems to have decreased considerably. For example, my initial readings were roughly 823 watts at 2300 RPM with an estimated GPM of 61.14 and 33 ft. head. Today, I'm seeing 683 watts at 2300 RPM, reducing the estimated GPM to 36.94 and 39ft. of head.

I've cleaned out the basket in the pump, and the filter was cleaned about 5-6 months ago, and backwashed about 2 months ago. I recently had to replace my salt cell, which is a Jandy AquaPure 1400, and replaced it with another Jandy 1400. The pool chemistry is good, thoug hI have added chemicals in the recent weeks to eliminate the Phosphorus and increase the conditioner in the pool.

Any advise here would be greatly appreciated.

 

[mas985]

If the filter pressure is higher than normal, then it probably needs to be cleaned. A dirty filter and higher filter pressure results in lower flow rates and wattage readings.

 

[batterfierd]

I should have mentioned, but the filter pressure is fine. It's at 10psi, same place it was at after the cleaning. The filter itself is a DE filter, and about 10 years old. I'm not sure if that matters or not.

 

[mas985]

The reduced wattage should correspond to a change in filter pressure. Do you remember what the clean filter pressure was at full speed and can you check that now?

 

[batterfierd]

I don't. I know the filter pressure at a lower speed, 1900 RPM, and it's the same now. But are you saying that's not relevant, and I should be comparing pressure only at full speed? If that's the case, I wouldn't know, and I guess all I'd be left with is the choice of cleaning the filter again, which seems premature given the last time it was cleaned.

 

[mas985]

The reduced wattage is indicative of reduced flow rate and that can occur with several changes:

Dirty filter
Clogged impeller or suction line
Change in the plumbing system (i.e. cleaner engaged, valves changed, etc)

So you might want to check all of these things especially the last one. Did you change anything when the wattage changed?

 

[batterfierd]

For the rest of the plumbing, I did replace my old salt cell with a new one, and Jandy moved from a 2 port to a 3 port cell, so some minor plumbing rework was needed, but nothing outrageous.

I don't believe the suction line is clogged, at least I don't see how that would have happened.

I do have two diverter valves in front of my filter pump. The first is for control between the skimmer and main drain. I pulled that off, all looks well, and there is no difference in flow regardless of the valve position. The second diverter valve is for the pool/spa function, and again, no difference in flow. So I'm hoping that likely clears up any intake issues, since I think it's unlikely that any clog would impact both the pool and spa.

And unless you think it's likely that the salt cell in line after the heater is the problem, then I guess I need to set my sights on the filter. I just can't imagine it being dirty already, but maybe its time for a cleaning. Do DE filters become less effective over the years, even with proper maintenance?

 

[mas985]

I don't believe the suction line is clogged, at least I don't see how that would have happened.

Sometimes it doesn't take much. It can happen when opening a pool during vacuuming at lot of leaves or debris or if debris gets past the skimmer it can sometimes lodge in the impeller.

It would be very odd for the pump power to change without a change in the plumbing somewhere.

 

[batterfierd]

Thanks for all of your help on this.

What's the best way for me to check this? The pipes right out in front of the pump look fine, and at the skimmer look fine. Obviously checking in between will be difficult.

Would I need to open up the pump to check the impeller? It has a strainer basket in it, so I'm not exactly sure how any large debris would end up in the pump.

 

[mas985]

The easiest thing to do is to remove the pump basket and reach down into the impeller inlet and see if you can feel anything stuck in there.

Also, to clear a suction line clog, you can use a hose stuck into the pipe that enters the pump basket and wrap it with a wet rag to seal it and turn it on.

If that doesn't work, you can try backwashing the filter and see if that was issue. Other than those three things, the only other possibility is that the new cell is adding more head loss than the previous one or the changes to the plumbing might have more restriction somewhere.

Also, I forgot to mention that if you are using one of my spreadsheets, the data fit I use loses accuracy at lower RPM values, so it is best to calibrate at high RPM and then use the second column for the lower RPM. So the flow rate may be higher than what you were showing in the first post.

 

[batterfierd]

Thank you very much for your help on this. It ended up being the filter. I dont understand why, since I just cleaned it 3 months ago. I did add some chemicals to remove phosphorus and add conditioner (at different times) which I've read can clog the filter, so maybe that's what did it.

In any case, I'm back up to where I was before. Thanks!!!

 

[mas985]