Woods Timer Failed - Acid Overdose (Yikes!!)

Jaimslaw

LifeTime Supporter
Jun 5, 2015
321
San Diego, CA
Now have an equal appreciation for ensuring that my Stenner Pump does not run continuously (the other more often discussed concern amongst others here being to ensure the Stenner doesn't run when pool pump is off).

Long story short, consecutive util. co. power interruptions caused Woods Exterior timer to malfunction and continuously dose pool with MA. As luck would have it, I spotted the Stenner still running about 5 hours into 1st day of malfunctioning. Crazy low ph levels were addressed before any real damage could occur...but have taken steps to protect against that from happening again.

Considered changing to the WiOn wireless timer but actually found it easier to do minor dosing timing adjustment at the Woods Timer itself while I am outside tending to weekly pool chores vs. going inside to retrieve my cell phone or tablet to adjust via wireless device using the WiOn.

In view of any digital or mechanical timing device having the potential to go bad and cause the Stenner pump to just keep running (tho some have less potential than others), I stuck with the Woods Timer - they are only $19. With a multi-plug adapter connected to the Woods timer, one line out is to the Stenner and the other is now a line out to an exterior rated mini halloween effects strobe light. I spray painted the strobe shell green and concealed it on top of my pool equipment wall amongst the trumpet vine. It strobes with the daily 3 minute dose time about when I get up every morning.

Not a perfect solution but this inexpensive and simple set up dramatically increases the odds of spotting a timer malfunction and consequent acid overdose. The activated strobe light can readily be seen even in broad daylight, alerting me to a malfunction if I should see strobing past my scheduled dosing time.

I'm sure other safeguards arrangments could be set up but this works for me.

I remain a huge fan of automated acid dosing. Never had such rock solid, consistent ph levels with virtually no maintnence except for annual Stenner tube maintenance and filling up acid container once every six months.

Cheers to all.
 
Not a bad idea...given how inexpensive they are, might just buy one more and hook two up in series. And Keeping the strobe will allow peace of mind in view of some Amazon buyers of the Woods timers who've had successive units go bad on them.

Can't be too careful when automating MA dosing.
 
This why the commercially available systems all have dose-counting logic in the controller to implement a daily hard volume limit. This way, the units can't dose beyond a hard-coded volume limit. It's annoying to those that have high acid demand pools BUT it keeps your pool from getting hit with a tank full of acid.

Glad you caught it early.
 
I grabbed another Woods timer per Mike's suggestion. With the two timers connected in series and the strobe light set up, I'm feeling more at ease about the MA dosing. Because all timers IMO can malfunction and lead to a dangerous acid dump, pretty sure tandem timers hooked up in series should be SOP when going with automated acid dispensing. That extra $20 is well worth the added protection.
 
Thank you for confirming this works as expected. Do you think there will be battery failure for the timer that does not have a constant source of power? Please keep us updated :)

This is the main hurdle that is keeping me from acid dosing in this manner...
 
Thank you for confirming this works as expected. Do you think there will be battery failure for the timer that does not have a constant source of power? Please keep us updated :)

This is the main hurdle that is keeping me from acid dosing in this manner...

In a test done late last year, I was able to verify that the Woods timer retains its setting in memory for at least 48 hours without having any power connected to it. So no problem insofar as battery life w/out a constant source of power.
 

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I just hope it works long term with only getting a few minutes of juice everyday. Thanks again for testing!

In my setup, like so many others, the power to the Woods timer is supplied during the full run cycle of the pool pump. This means the timer is supplied with power for several hours each day. The Timer stops being fed power when the pool pump shuts off ( which of course, is what keeps the Stenner Pump from running during times the pool pump is off).

Woods timers are known to go bad...like every other product. I guess a case could be made for mechanical timers being less prone to glitches. If going with a mechanical timer, the timer would have to always be connected to an "always on" power source to ensure continuous operation of the timer. In a set up where the mechanical timer controls when power is sent to the Stenner pump, you would splice into the power cord to the Stenner pump so as to route the hot wire of that power cord to the switch leg/relay for the pool pump (neutral & ground wires left alone). Thus, irrespective of any problem that might occur with the mechanical timer - including a power outage that messes with the on/off setting- the Stenner would only be able to run when the pool pump is running. This configuration requires proper connection/splicing of that power cord hot wire so as to be code compliant. Also FWIW, this is only one of many possible wiring configurations that can be devised to ensure the Stenner pump does not run when the pool pump is off (and admittedy, is not the optimal wiring configuration).
 
Intermatic makes a standard dual timer setup for 2-speed pumps. The primary timer sets when the pump is powered on and the secondary timer is slaved to the primary and determined when the "high speed" runs.

Couldn't that timer be used in this instance - the primary timer powers the pump and the Stenner is only controlled by the secondary timer? In this case, there would be no worrying about two timers being out of sync and the timer mechanism is always powered on. Obviously this isn't a "wireless" solution but these types of mechanical timers have been around for ages and are fairly bullet-proof in their operation.
 
Just to understand your dual speed pump scenario, would not this require a reconfig of one's pool pump timer setup?

- - - Updated - - -

I am wondering if there might be a mechanical solution here, such as pumping from a secondary reservoir that is connected to the main tank and refilled with a low flow dripper.

I was thinking along similar lines.ie, a mechanical means that does away with timer malfunction issues. Maybe where the pressure from a pool supply or return line provides the "power" source for a pump device of some sort. This device would have an impeller that the water pressure would cause to be turned and thereby create a vaccuum or suction that would then draw the MA/Cl from a tank into a port in the pool line. Would then need valve to be able to adjust flow rate as the pump device would be running during the entire pool pump cycle. Would entail three pool line entry (& exit) points...from pool line to mechanical pump device and return back to pool line, and then a supply line from the MA/CL tank to the pool line.

Probably would be insufficient pool line pressure generated to create adequate draw via this "device.".
 
Hmmm, I wasn't trying to be simple... I thought you had one timer plugged into another such that they both had to be on in order for the Stenner to receive power. I thought the second timer (the one connected to the pump) would only receive power during the few minutes it runs during the day.

Hope it works for you, because I'll probably use your plan as a blueprint for my future setup. :)
 
Hmmm, I wasn't trying to be simple... I thought you had one timer plugged into another such that they both had to be on in order for the Stenner to receive power. I thought the second timer (the one connected to the pump) would only receive power during the few minutes it runs during the day.

Hope it works for you, because I'll probably use your plan as a blueprint for my future setup. :smile:

Yes, I could have been a lot clearer in explaining my timer configuration/settings.

I have two timers: the first timer (timer #1) that is receiving power from the pool pump relay is set to a run one hour each day. It gets juice for the full 6 hour pool pump time frame. The Woords timer below it (timer #2) that governs the Stenner run time is set to run 3 minutes each day. So it is fed an hour of juice each day. If Timer #1 should glitch and go into a permanent ON mode, Timer #2 is there to ensure a maximum 3 minute run time. If Timer #2 goes into a permanent ON mode, the most the Stenner pump will run is the one hour that timer #1 is set to.

My Stenner puts out .89 of an ounce per minute - so an hours worth of acid is the worst case scenario (53.4 ounces total ounces or a little less than 1/2 gallon). I can live with that - plus the strobe light is hooked up as another quasi fail safe (will strobe beyond the 3 minutes the Stenner is set to run if glitch with one or both timers should occur - increases odd of detecting a permanent ON mode).

I actually am experimenting with the length of time the Woods Timer internal battery will keep itself charged without being hooked to a power source. I recall when I purchased the first Woods timer last fall (the one that glitched into permanent ON mode due to back to back power outages), it kept its display showing for 5 days following a charge of about 6 hours. I never tested it beyond that 5 day period but its possible it could have gone for a lot longer. One Amazon poster claims his Woods Timer was still showing its display two weeks after he unplugged it. I have to believe the retained charge is quite long given how little juice the unit's timer board and its led display consumes. I've got another one on order for another use and plan to fool around with the battery retention length for different intervals (more geek factor stuff for me to do). It may be that just a few minutes a day is plenty. I'll report back those results.
 
Ahhh, I see... that makes sense :) thanks for helping me understand. I don't doubt the LCD portion would last a long time with minimal power. Admittedly I have no idea how it switches power on/off but conceivably that would cause a greater draw. I think that concern is addressed with providing an hour of power a day to the unit.

I think I will do something similar with my setup, although given my higher feed rate I may only dose every couple of days. Luckily I've found that if the tank is actually touching the outside of our house it is audibly very apparent when it is running. My main concern is being away on vacation, so maybe I'll just look into keeping less in the tank.
 
The Stenner does have a noticeable low frequency hum that, if it had to run for an extended period, would be quite an auditory nuisance IMO. Its sound is not quite drowned out by the pool pump because of the difference in frequency between the two sounds.

Keeping a lesser amount in the tank while away on vacation would be a safeguard against a timer glitch induced acid dump. it's far preferable to have a relatively harmless spike in ph levels from a dry tank than a boatload of acid dumped into the pool. Per my original post, this could have happened with me were it not for pure luck in the glitch occurring on a weekend when I vaccuuming up leaves in the equipment pad area.

Wish the Wion wireless timer had a feature where it could be programmed to send a notification to your cell phone if it detected any kind of a glitch in its run program - assuming that function would itself be glitch free.
 
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