AutoPilot Digital questions & math verification

[VladSI]

Hey all,

I've decided to go with AutoPilot digital as my SWG choice after researching on the forum. It looks like a solid and mostly trouble-free system. After the research, I do still have a few questions that I hope you all can answer for me...

1. The manifold looks like it has 2" connections. My plumbing is 1.5". Is a reducer ok to use or should I re-plumb everything to 2" (which still requires reducers elsewhere).

2. I've read that the AutoPilot no longer includes the pump relay. Do I just call up Autopilot requesting it and they'll send it gratis? Do I have to purchase it?

3. Currently, I've got a 110 outlet by the equipment that is not dedicated. My neighbor is an electrician and will run a new circuit/line for me. Should I make it 220 or 110? What's the difference to the SWG since it seems that it's field convertible to either? If I get the pump relay, does using 220 for the SWG impact the 110 pump?

4. Per the manual, there are 2 pump programs. Does that mean 2 pumping durations per day? In other words, run the pump 6am-8am on program 1 and then 6pm-8pm on program 2?

5. And now the toughest question of all - sizing. I *think* that my turnover rate is about once per hour or hour and a quarter. As such, I only run the pump about 4hrs per day which is still probably overkill. To be able to keep the pump run-times low, I'm thinking either RC-42 (40k) or RC-52 (50k). On the 40k rated cell, I would need 3.6 hours at 100%. On the 50k cell, 2.9 hours at 100%, which is what I'm leaning towards as that would allow me to lower the % and give me more variables to play with than just pump run length. This is all assuming that their rating is based 100% power 24hrs a day. Are my assumptions correct? Is my math ok?

Thanks!!!!

 

[jblizzle]

1. If you are doing plumbing work anyway, replacing the pad plumbing with 2" can help the flow rate, but not required. Just use reducers where needed.

2. No idea

3. Usually the SWG and pump are powdered on the same circuit and timer. Is your pump only 115V or can it be switched to 230V? The advantage of using 230V is that the wire runs can be smaller because the currect is lower.

4. No idea.

5. We typically recommend a cell that is 2-3 times larger than the pool, so 40K is pretty large. I don't think the math works the way you think it does. You need to look at the output rating of each unit (in pounds of chlorine) and that is what it will produce in 24 hours at 100%. Then you need to look at how much chlorine you have to typically add in a day and that will tell you how long the unit will need to be run. Buying a SWG that is rated for 8 times the size of your pool just seem rediculous to me. It is going to cost you more upfront and will cost you more when you need to replace the cell.

If you want to save money on power, then consider replacing the motor/impellor on your pump with a 3/4HP 2-speed motor.

 

[JasonLion]

2) Some dealers include the relay automatically, almost all of the others will include it on request. If you already have your unit, call up AutoPilot and see what they will do for you.
4) Yes, you get to set two periods during the day (well 24 hour period) that the pump runs.

 

[VladSI]

1. If you are doing plumbing work anyway, replacing the pad plumbing with 2" can help the flow rate, but not required. Just use reducers where needed.

Flow would still be improved even if I need to use reducers on the filter, pump and skimmer which are all 1.5"? Wouldn't the reducers limit the flow? I'm just looking for some education here.

3. Usually the SWG and pump are powdered on the same circuit and timer. Is your pump only 115V or can it be switched to 230V? The advantage of using 230V is that the wire runs can be smaller because the currect is lower.

From the information I can find online, it's 110/115 only.

5. We typically recommend a cell that is 2-3 times larger than the pool, so 40K is pretty large. I don't think the math works the way you think it does. You need to look at the output rating of each unit (in pounds of chlorine) and that is what it will produce in 24 hours at 100%. Then you need to look at how much chlorine you have to typically add in a day and that will tell you how long the unit will need to be run. Buying a SWG that is rated for 8 times the size of your pool just seem rediculous to me. It is going to cost you more upfront and will cost you more when you need to replace the cell.

How do I determine how much chlorine I'm adding now in pounds (bleach)? Also, in terms of cell replacement, with my sizing, the pool should disintegrate before the cell dies .

 

[jblizzle]

Head loss is additive. Going to larger diameter for fittings (90s, tees) ... most of which are on the equipment pad ... will lower the over all resistance and thus increase the flow rate. There is not reall "maximum" flow through a certain fitting or pipe.

Also, if you have say two 1.5" suction lines (skimmer and floor), if you combine down to a single 1.5" pipe on the pad that is a 50% loss in flow area, but if you combine into a single 2" at the pad, that is only a 10% loss in flow area.

Now is it worth doing? The actual affect on flow rate may be minor and it is probably not worth changing things just for this reason. But, if you are changing some of the plumbing anyway, it does not cost much more to bump up the pipe and fitting size.

I am not sure if the Autopilot being wired for 220V can supply 110V power for the pump ... I do not know how that setup works.

Somewhere there is a list of how much each SWG is spec'ed for. Here is one source, not sure how accurate/up to date it is:
http://www.discountsaltpool.com/Full_Ma ... arison.htm
That is pounds of chlorine gas. Use the poolcalculator.com to figure out the PPM rise you would get.

Both of the ones you listed appear to produce more chlorine that the Hayward I have. My pool is 3 times the size of yours and I am running it at around 30% for 12 hours. So if all things were equal, it should work on your pool at 30% for 4 hours or 60% for 2 hours and produce the same amount of chlorine. So again, those SWG seem WAY larger than you should need.

 

[VladSI]

Thanks, Jason.

I totally get the point about resistance with fittings. I will consider going to 2".

Taking into consideration the chlorine output of each unit and my avg daily usage (2 oz or 2.5 ppm), I did some calculations and it looks like I need either the RC-36 or RC-48

For a 4hr run time, the cell % needed (at power level 3) would be
RC-36 = 59%
RC-48 = 48%
RC-60 = 37.5%

 

[jblizzle]

FYI, Running a SWG at higher CYA levels and lower FC levels seems to result in a different FC loss. I was losing 3-4ppm each day while using bleach, but now see that the FC is stable and the 12 hours @ 30% appears to only be adding 1.5ppm each day.

I think you are over-thinking

And you pump is still quite over-sized. If you put a 2-speed motor on it, you could run on low for 8 hours to move the same amount of water and still save 50% of your electrical usage.

 

[VladSI]

I'm at 60 CYA right now which is right around the recommended level for SW. Yes, the pump is over-sized. The pump is also only 3 weeks old. For me to purchase another pump, I'd need to shell out $200 minimum. How does that make financial sense to save money on electricity? Let's take pump replacement off the table for this discussion.

Yes, I do tend to over-think things. I'm in info tech and being a thorough analyst comes with the territory.

So I get that you are telling me that this setup is overkill. Other than pump replacement (off the table), no alternatives have been offered up. I did do my research and am leaning very heavily towards AutoPilot. Based on forum feedback, it seems to be the most reliable system. I am perfectly willing to pay more so I can play more and maintain less. I leave for work at 7am and don't get home until 7pm at the earliest. I can't deal with a system that constantly needs to be monitored for breakdown.

 

[jblizzle]

I can't deal with a system that constantly needs to be monitored for breakdown.

That seems a little overly dramatic. Any of the SWG will generally work fine and any of them can have problems. I hope you also realize that a SWG does not make the pool maintenance free, you still should be testing thing almost daily ... especially the pH will will tend to rise depending on your TA.

I am not sure what alternatives you would like me to bring up. All I am saying is that the SWG you have mentioned seem to be oversized and you could save money getting a smaller one. But, that does not seem to be a concern.

Another note, say you are running the SWG at 10% (because it is way over-sized) and you need a little more FC and you only have increments of 5% ... well changing from 10-15 is a 50% increase in FC. If you started at 50% and added 5% more, that is only a 10% increase in FC. So, there can be problems when the SWG is WAY over-sized. Although given you short run time, this may not be a problem.

 

[VladSI]

I know that I can't eliminate the possibility completely but I'd like to reduce the probability as much as I can. I currently test and adjust FC daily. The pH is tested and adjusted weekly. My pH currently has a tendency to drift down, especially after a rain storm (acid rain in NYC). The SWG might actually even out the effects. TA is about 80-90 which I know needs to be lowered for SWG.

To your point, since my run times are short (and can be shortened much further), I should be good to go with the RC-36 and a power level of 2 or 3. Level 2 should put the % in the 60s easily.

Thanks for all your feedback, Jason. This conversation has been very productive.

Hopefully, Sean will jump in with his opinions too. He seems to be the AutoPilot expert on the forum.

 

[harleysilo]

Well you can shorten your pump run time, to the minimum required to keep your water to your liking. With a oversized SWG you could run into needing more filtering with no more FC added. I have issues because my pool is always covered with an opaque cover, so little loss of chlorine to sun and little pump run time needed for filtration. I run my SWG below 10% consistently and am constantly fiddling with it to keep FC low (on target). In fact it's turned off right now and I won't need to turn it back on for probably a week, my FC spiked to 12ppm due to my fiddling.

 

[VladSI]

That's a really good point that I didn't think about. I, too, use an opaque solar cover. Thanks!

 

[peterdaly]

My AutoPilot was installed with 1.5" reducing sleeves to match the existing pool plumbing, and yes, it comes with 2". If you plan on converting anything to 2"...then don't glue in reducing sleeves. From what I've heard, it's always a good idea to convert to 2" where you can if you have a variable speed pump, but that's not really a SWG/AutoPilot discussion.

My AutoPilot gets fed 220 from the same 220 relay that controls the 220 pump. In my case, I'm using the AutoPilot in "Manual Timer" mode, and not using the built-in AutoPilot timer/control function, so it's wired directly with the pump itself on the switch side of the 220 pump relay in my OnCommand controller.

 

[Poolsean]

Vlad,
Most often I tend to not comment when it's a question on opinions of AutoPilot, as I do work for AutoPilot and don't want to answer with any bias. However, since you asked me specifically to chime in...
The AutoPilot can be wired for either 110 volts or 220 volts. The Timeclock Relay is available at no charge, and should be ordered at the same time as the DIG unit. If not, the dealer you get the DIG from can order it for you, at no charge.
Regarding the 2" plumbing, I would also recommend upgrading as much plumbing to 2" as you can, but in either case, you probably won't notice too much of a difference. To be technical, you would need to calculate the Equivalent Feet of Head, based on all your fittings, type of fittings, straight length of pipe, filter, valves, etc... then look at the difference between 2" and 1.5" head loss charts. IMHO, do it if you can, don't worry about it if you don't want to do it.

With 6,000 gallons, you can pretty much go with any size AutoPilot cell you want to, IF you use an external time clock. With an external time clock, you can program the DIG-220 to control the amount of time the AutoPilot is actually on. If you use the AutoPilot as your time clock, you will need to be careful as the unit be powered up whenever the pump is on. And while you can control the output and cell power of the DIG, the RC52 can easily overchlorinate, if the pump run is too long. However long that is really depends on how your pool is used. That is, if you have kids, dogs, neighbors, etc. using your pool daily and even worst on the weekends, the RC52 may be necessary. lol.
If it were my pool, I would probably go with an external 110 volt time clock to run the pump and AutoPilot, and consider using the Digital Nano Plus. This has all the features of the Digital, but without the different cell and power level options, and is sufficient for a 6,000 gallon pool...and quite a bit less.

 

[VladSI]

Sean,

Thanks for answering my post! I'm not worried about any bias as the decision to go AutoPilot has already been made . It's just a matter of details at this point.

I don't understand what advantage an external timer would give me. Can you explain further or maybe point me to a tutorial post? I've only been a pool owner for 3 weeks so I'm not familiar with all the products and terminology yet. I have a basic Intermatic timer right now but I suspect you may be referring to something else as, from what I can tell from the AutoPilot manual, the functionality between the timer I have and the AutoPilot's timer is the same. If you are referring to the the ability to run the pump without chlorinating, I thought that was something the AutoPilot was capable of by using the menu to turn the pump on manually (off schedule).

I did take a look at the Digital Nano Plus but some aspects are turning me off a little. First of all, it uses a cell which I don't see being sold as a replacement (RC-28). Second, there aren't as many retailers selling it online. And third, due to lack of widespread retailer availability, the difference in price between the two is less than $300. For that kind of difference, I'd rather go with the full-featured widely-used model.

 

[Poolsean]

One and the same time clock. The intermatic will then control both the AutoPilot and pool pump. As I said, if you're going with the larger cell, this is the method I would recommend. In this manner, you won't need the internal pump relay kit, and can program the AutoPilot to run the chlorine generator fewer hours than the pump, so as to avoid overchlorination.
However, if you use the internal pump relay option to control the pump, I would recommend sticking with either the RC35 or RC42. With the internal pump relay, whenever the pump is programmed to come on, it will generate chlorine, based on the Purifier % setting.

 

[JoshU]

I did take a look at the Digital Nano Plus but some aspects are turning me off a little. First of all, it uses a cell which I don't see being sold as a replacement (RC-28). Second, there aren't as many retailers selling it online. And third, due to lack of widespread retailer availability, the difference in price between the two is less than $300. For that kind of difference, I'd rather go with the full-featured widely-used model.

The Nano Plus just came out this past May. It is largely based off of the Nano which has been out for several years and has been in wide use. Since its release was in the middle of the pool season not everyone has added to their product catalogs yet.

The RC-28 is a new cell that AutoPilot created just for use with the Nano Plus. Since any of the units out in field right now have only been out since May they are still covered by warranty so none of the dealers are offering them for sale yet.

 

[VladSI]

Thanks for clearing that up for me, Josh.

And a big thank you to everyone else who replied to my thread. You've all definitely educated me a little more on the topic and have given me some things to think about.

Love this forum!