autofill overflow question

[factotum44]

I’m getting a pentair autofill installed with my new build. Water supply will be hooked up during lawn/irrigation system repair at the capped pvc pipe. the arrow in the first pic points to the overflow fitting. Builder stated it won’t be needed since overflow drain is built into the pool (the arrow in the second pic). It will drain out a pipe downslope from the pool which is at the top of a hill with more grass and then a retention pond at the bottom.
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I want to be able to leave town for a week and not worry about water level (too high/low for skimmers, deck flooding) and just keep the same pool pump schedule.
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I reviewed the equipment install instructions and you can adjust the float to a desired water level. If water exceeds level, it will drain out the overflow, but not if it’s capped. I suppose this won’t matter if the sidewall pool overflow drain (2nd pic) is placed in the sweet spot to keep water flowing at the right height to the skimmers.
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Is there any situation that I might need the autofill overflow pipe instead of or in addition to the sidewall overflow drain?

My builder and his crew have been great and communication has been one of their best attributes, so this post is more to help my own understanding. Thank you for any information you can provide.

 

[ajw22]

What is the level of the bottom of your skimmer mouth?

What is the level of the top of the skimmer mouth?

What is the level of that overflow pipe in the sidewall?

What is the level of the overflow pipe in the Pentair autofill?

How much space will you have for water between normal water level and where water overflows?

With the Pool Builders setup if the autofill valve fails on, which they do, water will continously flow into the pool and out the overflow until you realize it or get your water bill. I haven't looked at the Pentair manual to see if you use their overflow they have a way of preventing that.

 

[JoyfulNoise]

If it’s a simple ball float valve, then the chances of them failing open is minuscule. It’s usually the toilet bowl style fill valves that have issues with failing open. My float valve has operated flawlessly for 10 years but, again, it’s the very simple bladder float style.

My auto fill drain pipe was capped off as well. No need for it. Since you have a separate wall based overflow port, then your builder is correct that the auto fill pot overflow is redundant and unnecessary.

 

[factotum44]

If it’s a simple ball float valve, then the chances of them failing open is minuscule. It’s usually the toilet bowl style fill valves that have issues with failing open. My float valve has operated flawlessly for 10 years but, again, it’s the very simple bladder float style.

My auto fill drain pipe was capped off as well. No need for it. Since you have a separate wall based overflow port, then your builder is correct that the auto fill pot overflow is redundant and unnecessary.

I can’t tell the actual float design based on the instructions, but it looks like that part is made by fluid master. I couldn’t take any measurements without risking damage to the cantilever coping forms but eyeballing skimmer and overflow drain height—-it looks fine. thank you for your response.

 

[tim5055]

Water supply will be hooked up during lawn/irrigation system repair at the capped pvc pipe.

I will just point out that in many jurisdictions an autofill can not be connected to an irrigation system as the source of water. Irrigation is considered non potable water due to the possibility of backflow. Almost all areas require a RPZ (reduced pressure zone) backflow preventer between the potable water supply and the non-potable water lines (like irrigation). Some jursidictions go so far as to require a yearly test/inspection of the RPZ.

 

[factotum44]

I will just point out that in many jurisdictions an autofill can not be connected to an irrigation system as the source of water. Irrigation is considered non potable water due to the possibility of backflow. Almost all areas require a RPZ (reduced pressure zone) backflow preventer between the potable water supply and the non-potable water lines (like irrigation). Some jursidictions go so far as to require a yearly test/inspection of the RPZ.

The builder mentioned likely needing something like that but figured irrigation folks would deal with it. Irrigation system already has one. Seems strange they would require a direct waterline from the house/street and backflow preventer rather than allow tie in to irrigation system which already has backflow preventer and also given that pool is chlorinated. Sounds like I may have wasted some money. I don’t want to trench a waterline around my house. Yard is torn up enough.

 

[tim5055]

Seems strange they would require a direct waterline from the house/street and backflow preventer

While it may seem strange, once past the backflow preventer that covers the irrigation system it is considered non potable water as a pressure drop in an irrrigation pipe could suck lawn chemicals into that pipe.

Probable, no. Possible, yes.

Pools should only be filled from a potable water source, even with proper sanitation procedures being followed because chlorine won't eliminate the lawn chemicals that "may" accidentally get in the pipe. Once a water source is considered non potable, you can't change it back.

Building codes are written to try to make things fool proof. You know how you set up the plumbing, but the next owner may not. They may install a water fountain off of that autofill water line that is supposed ot be potable water.

 

[factotum44]

While it may seem strange, once past the backflow preventer that covers the irrigation system it is considered non potable water as a pressure drop in an irrrigation pipe could suck lawn chemicals into that pipe.

Probable, no. Possible, yes.

Pools should only be filled from a potable water source, even with proper sanitation procedures being followed because chlorine won't eliminate the lawn chemicals that "may" accidentally get in the pipe. Once a water source is considered non potable, you can't change it back.

Building codes are written to try to make things fool proof. You know how you set up the plumbing, but the next owner may not. They may install a water fountain off of that autofill water line that is supposed ot be potable water.

I didn’t think about lawn chemicals. Thank you for elaborating.

 

[darkrider]

The overflow outlet at the back of the autofill is much smaller than what will likely be installed on your pool wall. Our PB did not connect the overflow outlet at the autofill, but rather used the larger wall outlet, and added a cutoff valve behind our decking. Most of the time, I leave the valve closed, so I will be able to tell if my autofill is leaking. However, it only takes a minute to turn the valve to open when we go out of town.