I've given much thought to this leak detection caveat when using auto-leveling. It's why, I think, some PBs don't like to install them. And I have a few notes...
Because the filler and overflow are in the same well, and covered from sight (and somewhat from sound), it's possible that if the valve gets stuck on, the water will just flow right out the overflow and continue to, undetected, indefinitely, until discovered. This could amount to a massive amount of water loss (and associated cost). And that
did happen to me once, so it's a real concern. I must have caught it pretty quick, because the event didn't show up on my water bill, but it definitely could have been much worse.
I've negated this issue in several ways.
- I believe my valve's failure was caused by a build up of calcium in the mechanism. Since switching to soft water for fill, I believe that will significantly reduce this risk. In fact, it occurred right after I altered the plumbing to the filler, so I probably broke loose some crud in the pipe that got caught in the valve. So that one was on me. That's not to say the valve couldn't fail for any number of other reasons. The valve is basically a toilet tank valve, and those
do fail. It likely worked without failure for 5 year prior to that. It's been working fine for three years since.
- I plan to pro-actively replace the valve (about $25) every five years or so. Further reducing this risk. It's a simple DIY process (10 minutes).
- I check my skimmer basket regularly, usually once a day, and check my filler valve at the same time (they're right next to each other). So a failed valve is not going to run for weeks or even for more than a few days. Checking on your pool and pad for failures is pretty much a daily necessity anyway. Any less and you are at risk for any number of expensive consequences. So the existence of an auto-leveler system doesn't necessitate additional observation, it's just part of the normal observation.
- Because my overflow level is adjustable, I've adjusted that level to be significantly higher than the fill level (those two levels can be adjusted independently). Which means should the valve fail, causing the water level in the well to increase enough to spill into the overflow outlet, the level of the pool will also increase the same amount. Which will be very obvious with even a casual look at the pool, even from inside the house (or via my "pool cam" while away). Unless I completely ignore my pool for days or weeks, a catastrophic water loss is just not going to happen. In reality, I look at my pool every day, usually several times a day, so the most I would lose would be 24 hours worth, if the failure occurred the minute after I last looked. That very low-probability risk is completely acceptable to me for the convenience the system affords me.
And because I know from experience, too many times to admit to, that filling from a hose or manual fill valve could get forgotten about until a day or two later, I would waste (HAVE wasted) far more water doing that then from some unlikely valve failure. So for me, the risk of an auto-leveler is far less than the risk of my own faulty brain. And it is that same faulty brain that would be far more likely to let the pool evaporate below the skimmer causing a main pump failure, which would be considerably more expensive than a high water bill.
To be thoroughly fair here, the notion that one would notice the pool too full (indicating an auto-filler failure) could not be applied to the use of an auto-leveler I cited above: keeping an exact height of water over a baja ledge, because to do that you need to adjust the fill level and overflow level the same. So if you were using auto-leveling for that purpose, you'd never see the valve failure just by looking at the pool, you'd have to regularly check the valve itself.
So that's what I have to say about that!
