Why is my Autopilot Digital Nano unhappy with pump speflow w

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Lovrpool

0
Sep 1, 2013
38
Ohio
We just had a fiberglass pool (13,000 gal) installed (2wks ago) and we have an Autopilot Digital Nano SWG and Sta-Rite Intellipro Variable speed pump. We wanted the variable speed for energy savings however the autopilot doesn't like anything less than 1500rpms. We are "pool illiterate" and I have been so thankful for this forum and have learned a lot!!

Is this normal to have to run the pump no lower than 1,500 rpms?

So far We have been running the pump at 1500 rpms for 6hrs during the day and 4 hrs at 2100 during the eve when we are usually on the pool the most. Another 2 hrs at 1500 and pump doesn't run at night. (Total run time 12 hrs during the day). Temps are in the 80s during the day 60s at night.

Appreciate any advice!!
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

Welcome to TFP.

Can you post a picture of the equipment pad? That will probably help us spot if there's something you can change plumbing wise.
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

First, fill out your signature with your pool stats and equipment list as outlined here: pool-school/read_before_you_post

Second, answer the following questions:

Filter pressure at full speed?

Filter gauge height relative to pool water?

Distance from pool to pump?

Suction line pipe size?

Also, you might want to check the SWG flow switch for any debris or damage.
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

Filter pressure At full speed (3450 rpm) is at 30psi. Cleaned cartridge filter last night as well as the SWG cell filter screen (which was clean).

Gauge height from pool water is 4'.

Distance from pool to pump is 30'.

Pool plumbing is 2"

When we checked the filter screen we wrapped it in plastic and reassembled and turned the pump on to flush out any debris. How would we know of the flow switch is damaged?
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

From everything you mentioned, I estimate that the flow rate should be about 40 GPM at 1500 RPM and 26 GPM at 1000 RPM so it looks like it should work fine. Are you getting decent flow rate out of the returns at 1000 RPM?

Also, do you know the type of check valve that you have? Flapper or axial spring type. If the latter, those can add a lot of head loss to a plumbing system, especially at low speeds. What was the filter pressure at 1500 RPM?
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

Not sure on type of check valve. Turning pump down to 1000 rpms the psi is 1. Could drastically tell a difference in the flow of the returns when went from 1800 down to 1000. At 1500 rpms it is at 5 psi.
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

It is seems like it is one of two issues. The check valve is closing down on low speed further restricting flow rate. Or there is something wrong with the flow switch (which you have already inspected). I don't want to have you replace the check valve without knowing which type it is so is there a part # on the valve anywhere. Can you take a close up of the valve? Can you ask the PB what brand/part# he used?

Also, when was the last time you cleaned the filter? It might be worth a try too.
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

The check valve is the spring type. It has a sticker on it that says "3lb spring".

We took the cartridge filter out last night and sprayed it off real good.

Tried reducing the rpms on the pump to 1480 and the autopilot got unhappy pretty quick. It's stubborn at needing it at 1500 for the 'check flow' error to go away on the display.
 

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Re: Why is my Autopilot Digital Nano unhappy with pump spefl

Unfortunately, I think the problem may be with the check valve. 3 lbs is way to strong for low speeds. The lowest head loss check valves are like this:

jandy_checkvalve.jpg

http://www.zodiacpoolsystems.com/Produc ... Valve.aspx

That type of check valve should never have been installed and I would try to get your PB to replace it with a Jandy flapper style check valve.
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

That wasn't the check valve that I was referring to. The one I am referring to is between the heater and the SWG setup and it looks like this:


pvc-spring-check-valve-solvent-by-solvent.jpg
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

Yes, between the heater and the SWG loop.
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

That is an irrigation check valve and should never be used on a pool. Your PB should know better. That type of check valve requires 2 PSI to open which at 1000 RPM is a problem because the pump cannot generate that much pressure and still deliver the minimum flow rate. That is most likely the cause of the problem.

If it were my pool, I would demand that he replace it with a proper check valve at no charge.
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

Thank you Mark!!!!!! I just saw that on the lowes' site for the specs that it requires min. 2psi. Oh geez. Just sent an email to the PB to switch this out to something that is more compatible with the system we have. Thanks!!!!! This forum rocks! :)
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

Saw new check valve part next to equip. Not installed yet. It is a Spears 2" S1520-20 (swing check valve). Found specs online: min. Opening pressure less than 0.5psi, full flow (open) 150 psi, back pressure (closed) 75psi.

I couldn't find specs in the jandy other than says min. Hydraulic loss.

With 0.5psi the swg should allow me to run the pump under 1500rpms. This sound correct?
 
Re: Why is my Autopilot Digital Nano unhappy with pump spefl

I believe the Jandy valve opens at 0.25 PSI. The Spears might work ok but the Jandy has half the opening pressure and you can replace the valve without cutting into the plumbing which is a big plus. Any reason the PB doesn't want to use a Jandy?
 

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