3152 Osmolator Nano ATO not shutting off

AdamNC · Feb 7, 2019

My Tunze 3152 Osmolator Nano ATO has been acting up lately. Not shutting off randomly until it hits the 1:30 timer or longer, stops pumping 5-6 seconds AFTER the float switch is tripped. I confirmed it multiple times in the sink with a timer. One time the auto stop ran to 2:48 then randomly between 1:30-1:48 for the rest of the tests. I've already opened up the controller and confirmed that the jumper is on the 2 prongs and not just 1 for the auto shut off feature. I've cleaned the float switch confirming that it is not obstructed.

I was wondering if there is any kind of warranty on these, like a year or so? Tunze normally has a great warranty but I'm not sure if I need to go through you guys or BRS.

It was purchased April 5, 2018 from BRS and I have the digital receipt from them but not the paper one.

gatorbait01 · Feb 7, 2019

My Nano has been giving issues too. For me, I think the switch is somehow going bad. It's a few years old, but has been having issues enabling/disabling for the last couple weeks. I've cleaned the switch numerous times and it seems to work when I test it. Works for a day or so, then fails again. Is it possible to buy a new switch assembly?

AdamNC · Feb 7, 2019

I didn’t pay attention when I had the box open but I think the float switch wire is soldered in.

rvitko · Feb 8, 2019

The float wire is plugged in on the Nano Osmolator it is replaceable but more often then not the float is not the issue, floats usually last 4-5 years. It has a 2 year warranty. It should run 1 min 45 seconds before a time out, it also overfills 3 seconds after the float is raised, this varies a little, the float has a 3 second delay, it waits 3 seconds for the pump to turn on and 3 seconds for it to turn off but this can be as long as 5 seconds as their is some variability. This was added in 2016 as we found tanks with wavy surfaces will cause it to switch over and over and this reduces the life of the relay, so a slight delay to allow a wave to pass and a slight overfill to reduce switching cycles extends the product life in this circumstance. It is possible what you are seeing is normal and a power disruption or magnet or movement of the float switch reset the timer at some point roughly a minute in adding another minute. You are welcome to send it in, units made after 2015 we can connect to a computer and run diagnostics and get a readout of errors.

rvitko · Feb 8, 2019

The switch is part 3152.300, you can order them on tunze.com, but keep in mind this is a magnetic switch so a magnet nearby or even the magnet holder on thin glass or misaligned can actuate or pin the switch. This can also happen if another Tunze magnet holder was mixed up with the 3152 magnet holder which has a shielding inside and a purpose designed layout to not affect the float switch provided it is on glass 3/16-3/8" thick and lined up and not offset.

AdamNC · Feb 8, 2019

If magnetism may be a problem, would putting a piece of acrylic to add thickness help?

rvitko · Feb 8, 2019

Yes, but be sure to check off the other possibilities, if for example you swapped a magnet from a Tunze Stream to a Nano Osmolator, that is a much stronger magnet so the acrylic won't help much and it is very important the magnets are lined up in and out and not offset.