Circuit wiring…

[Pullstart 70,638]

I have a task.  I would like to add auto fill to the pool.  If anyone recalls, I only have the top skimmer working currently, and there is still a small leak in the bottom of the pool.  When we need to replace the liner in the next year or so, that issue will be fixed.

 

There is an auto fill kit for the tune of $1,000 and I realize there is some safety and security involved here.

 
This kit uses a sensor that hangs in the skimmer box.  It uses continuity to satisfy the call for water, and shutting off a fill valve (that will tie into the piping).  I imagine it is ultra low voltage.  24?  5?  I am not sure.  What is really stumping me, is how a normally open circuit will make a call for heat.  A closed circuit will shut down the system.

 

@8ntruck?  Any thoughts?  Water and electricity don’t mix… I’d like to not test this on guinea pigs, or even Uncle Jim.

[Pullstart 70,638]

This is the fill system sensor.  It is to hang in a stand pipe, or skimmer box.  I have a 3/4” conduit piped into the skimmer box and into the pump house.

[squonk 47,360]

That sensor works like a Manitowoc Ice Machine water level sensor. As long as water is touching both probes the board it's connected to senses water conductivity and knows there's enough water. When the level drops the conductivity stops and the board trips a relay that turns on the water supply. Probably 24 volts

[Pullstart 70,638]

@squonk so you’re saying I need more Wisconsin in my water?

[squonk 47,360]

3 minutes ago, Pullstart said:

@squonk so you’re saying I need more Wisconsin in my water?

Toss some cheese in it! 

[ri702bill 12,469]

2 hours ago, Pullstart said:

@squonk so you’re saying I need more Wisconsin in my water?

No, he means that you can lick your fingers, touch both probes & still live to talk about it since it's 24 VDC...

[wallfish 20,214]

4 hours ago, Pullstart said:

What is really stumping me, is how a normally open circuit will make a call for heat.  A closed circuit will shut down the system.

 

We do some radon water systems that have a mechanical fill and off system. Like a toilet does. Pretty simple and no electrical components.

Edited 14 hours ago by wallfish

[ri702bill 12,469]

1 hour ago, wallfish said:

Like a toilet

Somehow, pool & toilet do not play well in the same sentence.....

[wallfish 20,214]

Just in case you're interested in trying a mechanical fill valve

 

[8ntruck 9,039]

I'll  agree with @squonk.  Probably 24v dc.  That will probably run a relay that operates the valve.

 

By the way @Pullstart, what have you got going the next couple of weeks?  I've got to come see you.  I'm good maybe Wednesday or Thursday this week or after Wednesday next week.

Edited 9 hours ago by 8ntruck

[wh500special 2,430]

10 hours ago, Pullstart said:

…

 
This kit uses a sensor that hangs in the skimmer box.  It uses continuity to satisfy the call for water, and shutting off a fill valve (that will tie into the piping).  I imagine it is ultra low voltage.  24?  5?  I am not sure.  What is really stumping me, is how a normally open circuit will make a call for heat.  A closed circuit will shut down the system.

 

@8ntruck?  Any thoughts?  Water and electricity don’t mix… I’d like to not test this on guinea pigs, or even Uncle Jim.

I’ll agree that in this case water and electricity shouldn’t be mixed.  
 

You can “steer” the logic of your switched circuit using either normal open (NO) or normally closed (NC) relays.  Valves too are available either NC or NO, so you have options there.  (Edit: terminology might also use the words Direct Acting and Reverse Acting.)
 

in the case of a valve, you may also see it listed as a Fail Close or Fail Open, meaning when the control signal goes away it will either close (fail closed) or open (fail open).  Usually valve direction is chosen to give you a failsafe condition.  For instance, if you lose control power you probably want the valve to reliably close and stay that way lest you overflow the pool and flood the basement.  So you’d work out the logic that the valve closes if the power goes out, somebody pulls the plug, etc. 
 

 The manufacturer of the automatic fill device probably has the logic planned out using whatever combination of switching (the one in the water), relay (if used), and valve actuator they’ve determined to be the best failsafe combination.  They also might have selected the action of the switch to be in the direction it is to avoid false triggers due to splashes or waves from wind or swimmers.  
 

I also suspect there is some timing action going on with their control.  They may require the switch to be open for X minutes before triggering the valve to open.  Likewise, and to avoid rapid cycling, they may have a minimum time interval that triggers the valve to open and let water in also to avoid short cycling.  These are timer relay functions. 

 

If you piece together a diy system you’ll have to work out the logic that seems the most logical and failsafe to you.  
 

A mechanical toilet valve sort of thing takes away the risk of electrical malfunction.  If you do chose the electric route there is a range of marine/boating products that can be used to trigger an event.  For instance a solid state automatic bilge pump switch can get you there, although the action (NO) is

probably the reverse of what you’d normall be looking for. 
 

as for mixing electricity and a swimming pool, you’re on your own there especially if you source the power (or tie it in any way) to your house AC power.  There are ways to achieve safe isolation, but it’s not intuitive and I would venture is not in the playbook of a typical electrician. 
 

Keep in mind that even if you were to, for instance, power your system from a battery charger or AC to DC power supply and that even if you have 12V between your DC leads there is often nothing anchoring either lead (+ or -) to a safe reference/ground.  You may end up with that 12V supply floating at some dangerous potential relative to the water and the people in it. 
 

I’d probably just buy the off the shelf solution.  
 

good luck!

Steve

Edited 9 hours ago by wh500special

[8ntruck 9,039]

 @wh500special brings up a very good point about a safe reference/ground.  That didn't enter this retired mechanical engineer's mind. 

 

In Lake of the Ozarks in Mo. there are many electrified docks in that lake.  Over the years there have been a few deaths and many occasions where something went wrong with the wiring or whatever was plugged into it where people got shocked.  An insufficient or floating ground was the cause of most of those incidents.

[squonk 47,360]

I looked at the manual for this thing. The sensor reads just like I said. Same technology is used for boiler water level sensing.  Electronics read water touching the probes through conductivity. The electric to the probes is 24 v DC at 1 amp. 

[Pullstart 70,638]

Lots of good information here, and though I enjoy ribbing, it’s the meat and potatoes here that I was looking for!  
 

There is a lot of thoughts to chew on. 
 

One- false senses.

I would build this on a timer, so it only operates between midnight and 3am, or similar.  That should cut down on the waves and pump actions.  
 

Two- Toilet fill.

I have thought about this often too.  I could easily just build a drop in system and stick the hose on it.  I have limited space in the skimmer box, and I have a feeling that when my brother in laws come over for their self proclaimed cannon ball contest, the water may have the ability to break the mechanical valve.

 

Three - low water cut off sensor.

There is a float sensor in commercial water heating that I may be able to sneak through the conduit that’s plumbed into the box.  It’s small and stainless steel, and quite rigid.  It runs on 24vdc logic in the water heating industry as well.  That I am used to, in my previous life.

 

Four - liability and fail safe.

Self explanatory there.  I don’t want to get someone hurt.

[SylvanLakeWH 31,702]

My BIL has a fail safe system. Works every time. No electricity involved.

 

Hose in pool. Turn on. Drink adult beverage of your choice. Turn off.

 

Sometimes automatic stuff is way more desirable in a theoretical sense than reality...

 

[Pullstart 70,638]

2 minutes ago, SylvanLakeWH said:

Hose in pool. Turn on. Drink adult beverage of your choice. Turn off.

I think my check liver light would come on!

 

 I realize that right now I am in a unique situation, and can’t let the water get too low.  I also travel on occasion and can’t let it go a few days.