Mysterious VSP priming events

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C3Cl3N3O3

C3Cl3N3O3

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Bronze Supporter
May 25, 2015
460
Fort Mill, SC
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hey gang, this is an odd one for me. I've noticed some mysterious priming events with my Jandy VSFHP185DA2A. My schedule is as follows:

12:00 am - 4:00 am: OFF
4:00 am - 12:00 pm: 2000 RPM (Filter)
12:00 pm - 4:00 pm: 2350 RPM (Skim)
4:00 pm - 12:00 am: 2000 RPM (Filter)

I have a fountain hooked up now so the changes in pump speed are very visible. The fountain will be at one of three heights based on the speed. On three occasions, I've noticed the fountain unexpectedly at the 2750 RPM height which is the priming speed. When I check the app at this time, it shows the pump as "priming". After a few minutes, it returns to the normally scheduled speed. All three observations were around 4:45 pm, which is forty-five minutes after the pump slows from 2350 RPM to 2000 RPM. On the second occurrence, I was looking right at the fountain at the time. There was nothing unusual at the time, the fountain went straight from the low height to the high height with no sag beforehand. In all cases, there were no bubbles at the returns and no evidence of a leak or loss of prime. Flow at all three returns is healthy at all times. The water level is normal, with no chance of sucking air at the skimmer. The first two occurrences had DE in the sand filter, but I backwashed and did not replenish it prior to the third occurrence. The sand filter pressure has remained steady at 12 PSI since the backwash.

I've not observed it occur at other times, but that could be random chance. The fountain is new, but I think it is acting as the alert mechanism and not the cause. It's entirely possible this has been occurring for a while unnoticed.

I'm at a bit of a loss here, any ideas?
 
I put up the bat signal looking for people with experience with your pump. The only other thing I can guess at is the program times ending at starting on the same minute.

If you have no issue with priming (e.g. pump below pool, or pump always stays full) you could remove the priming cycle (set to zero) or minimise the duration of it. Would have to keep an eye it for a while and make sure it stays primed, but it would surprise me if it wouldn't prime at 2000 RPM. That's another alternative I suppose is setting priming to 2000 RPM. Only other I can think of is to abandon variable flow settings and go with variable speed settings, if that's possible on that pump.
 
Thanks, actually the filter schedule is 4:00 am to 12:00 am. The skim schedule overrides it for four hours, then it returns to filter. I just don't think the schedule is doing this directly.

I considered some sort of power glitch. I can't imagine what that would be. The pump is on its own 240 V breaker, and I don't see it reproduce when the AC unit or anything else kicks on.

I'm not even sure it is a problem that requires mitigation. That's really what I'm trying to tease out here. Sometimes these sorts of issues can be precursors to bigger things to follow, other times they are nothingburgers. This certainly has me a bit uneasy.
 
Can you remove the iQ thing and just run the pump alone to see if it still occurs? Like a Service Mode that we have on most automation systems.
 
No, as I said the pump didn't turn off between the 2000 RPM mode and the 2750 priming mode. It went straight into it, I was looking right at it.

What I am suspecting is incomplete priming. I do see some air at the top of the pump basket from time to time while running. I don't see bubbles at the returns, however.

Does this pump detect loss of prime and/or incomplete priming, and would you expect it to potentially switch to repriming while running in that case?
 

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C3Cl3N3O3 said:
Does this pump detect loss of prime and/or incomplete priming, and would you expect it to potentially switch to repriming while running in that case?
Click to expand...
I think most VS pumps will detect a loss of prime. The threshold for this one may be too sensitive for a change in RPM. Hard to say. What is the filter pressure when the pump runs at full speed (3450 RPM)?

But why not just stick with one speed that does the skimming well? Why run a pump at all if it isn't skimming? The pool is well circulated after the skimming mode anyway.
 
Honestly, I've never run it faster than the priming/service speed of 2750 RPM. There is a quick clean mode of 3200 RPM which I don't use. At 2750 RPM, it is usually between 12 - 15 PSI and I backwash around 20 PSI.

The Jandy installer set up the schedule and I've only made small adjustments. It seems reasonable to me to filter for 18 hours a day but run the pump a bit faster for 4 hours to improve skimming. It's always skimming when the pump runs of course, but I do see some surface debris lingering at the problem areas at the 2000 RPM speed. I haven't seen anything remotely resembling a consensus on TFP as to how to set these up. I'm open to suggestions. That said, with the fountain, there is an unexpected benefit that the circulation pattern changes between the two speeds which results in even more debris getting skimmed. I have overhanging trees and deal with a lot of debris.

I just checked the pump basket running at 2350 RPM. There is a small amount of air, but not much really. It has been cleaned recently. I suppose I can lube that cover O-ring for good measure.
 
Most on the forum will follow the following guidelines.

First is to find out the minimum RPM that is necessary for proper skimming. This is usually determined by the water flowing over the weir door vs around the sides. If the water is not traveling over the top of the weir door, it won't be skimming very well if at all.

Once that is determine, members will run at that speed for 24 hrs per day OR until the surface cleaned OR for as long as necessary for heating, chlorination or other functions. It just depends on what is required for your pool.

As for the priming issue, the pump should only go into priming mode if the flow rate decreases significantly like when a lot of air enters the pump basket. One possibility is that at lower RPM, the weir door may not be getting pulled down and the skimmer may drain of water and a lot of air enters the pump triggering the priming mode. Have you watched the skimmer and/or the pump basket during the start of the priming mode?

Do you have any check valves in the plumbing?
 
There are no check valves in the plumbing

I think the weir door may well be the culprit. There was one incident a few weeks back where I thought the door may have stuck open momentarily. I heard some sucking sounds coming from the skimmer and had a few minutes of bubbles coming from the returns. It's not a perfect match with the priming events but could well be the cause. Mechanically it seems to move without obstruction, and it always appears down with water flowing over it.

So, run the pump at 2350 RPM for 24 hours a day?
 
I can hold the weir door up and get the skimmer to run dry. So, water doesn't go "around" it much. I didn't hold it long enough to get any air in the system. It goes right back down, there seems to be ample flow at 2000 RPM to keep it down. My pool equipment is also below the skimmer level. So that's still a bit of a mystery. It could have an intermittent mechanical obstruction, I guess. I don't see how. In that case, increasing the pump speed may not resolve the issue.
 
C3Cl3N3O3 said:
There are no check valves in the plumbing

I think the weir door may well be the culprit. There was one incident a few weeks back where I thought the door may have stuck open momentarily. I heard some sucking sounds coming from the skimmer and had a few minutes of bubbles coming from the returns. It's not a perfect match with the priming events but could well be the cause. Mechanically it seems to move without obstruction, and it always appears down with water flowing over it.
Click to expand...
See if you can catch in the act. It might not be very consistent.

C3Cl3N3O3 said:
So, run the pump at 2350 RPM for 24 hours a day?
Click to expand...
24 or you might only need 4. There is no magic number. Personally, I like to run as little as possible. Solar heating dictates my run time. Everything else requires much less run time. In the winter, I run only 3 hours per day.

However, 2350 RPM seems pretty high for a single skimmer. I run at 1500 RPM (~30 GPM) and have two skimmers plus I have a very a low HP VS pump. The 12 PSI is a little high for that RPM as well so your system may have a lot of head loss requiring higher RPM. What size is the plumbing?
 
Really glad to see you have some true experts here :)

Just one thing... a couple of bubbles swirling around, clinging to the lid over the pump strainer basket, is nothing to be concerned about, provided those little swirling bubbles stay fairly consistent throughout an unchanged pump run. Just mentioning this so you can ignore that aspect. I kinda prefer a small bubble which makes it obvious water is flowing, haha (purists don't like bubbles, but for me, perfect is the enemy of good)

Also, once the pump is running normally, there's not really a chronic priming problem that isn't easy to observe. It's somewhat more of a "primed" or "didn't prime" kinda thing.
 
I did some experimentation at different speeds. The water level is halfway up the skimmer. I started at the 2000 RPM speed at worked my way down to the minimum 600 RPM. The weir door remains down with water skimming over the top at all speeds. At 600 there is barely any flow, but it is trickling over the door. Only when the pump is stopped does the weir door go up. I observed the pump basket at 600 RPM for a while and there was no air.

So, a weir door malfunction remains a possibility, but it isn't caused by insufficient flow. In fact, I think I'm going to reduce my "filter" schedule to 1400 RPM. There is a nice flow and skimmer action at that speed. I have no idea how Jandy guy came up with 2000 RPM as the optimal speed.
 
I've been putzing around on the patio all morning in and out of the pool running at 1400 RPM. It seems to all be running fine. The fountain is a little less dramatic, but I'm saving 50% on energy usage. That's a good tradeoff, assuming it doesn't exacerbate the priming issue (whatever that is) or cause my water quality to drop off. I'll be monitoring that.
 
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