Tunze 3155 pump won't stop pumping

[robert s b.]

I have a Tunze 3155 ATO, was working fine until recently, my eye detects the water level, when the green light turns on, but the pump keeps on pumping, but seems to be having a hard time, but it goes. Yellow light does not stay on but flashes and very feint. But it does stop on the secondary float valve when it starts the constant beep alarm. Is my pump bad or is it the circuit board?

 

[rvitko]

How old is it? I would lean toward a bad pump or corroded pump connector.

 

[robert s b.]

It's about year and half. I have tested 2 other pumps on it and still the same.

 

[rvitko]

Is this set up on a smaller tank or a larger tank? I had assumed an older unit was in use here, on a unit that is only 1.5 years old, the possibilities would be limited to:

1) The tank is smaller than 50 gallons and the deliberate overfill combined with close set sensors and the pump running at a higher speed (not turned down to nano) are causing the issues. During the deliberate overfill the lights blink and are on together, at the default pump speed about 1 extra cup of water is added to minimize repeated cycles.

2) The sensor has a relatively minor issue, it is dirty or due to moved equipment some bubbles are clinging to it. The sensor should be shiny when dry, if it is dull, it needs to be cleaned buy a few hours in vinegar and wiped with a soft towel.

3) The connector for the pump has a short due to saltwater or some corrosion is present. One bad pump is certainly possible but if 2 new ones have been tried I would rule out pump issues.

4) An error I have not encountered before is always possible.

If it was filling past the float my guess would be a siphon and I still would not rule that out entirely, make sure the hose terminates at the tank or sump above the water level that is in the reservoir, otherwise water will siphon until these levels are equal.

 

[robert s b.]

Hi Roger,

It is the older unit, I have a newer unit I my MT, this is on a nano and this unit does not have adjustability, only a jumper. Bought it at an LFS that had a few older models they want to clear out. It might be the connector. It is now giving me little power and the pumps are very slow, which is odd. Might be corrosion?

 

[rvitko]

Is the face of the controller blue or black?

Black with optic sensor is 2002-2009
Blue but without speed control for the pump is late 2009-end of 2011.

Their were many small circuit board revisions over those time spans, the Osmolator tends to get some minor tweak to the board every 12-24 months but that would help narrow down issues.

 

[robert s b.]

 

[rvitko]

It is pre 2009, one possibility is it is pre 2008 which had a different board that suited the pump of that time period. In 2008 the pump changed to a double seal, it looks the same but had a second seal added to increase the durability and that increased power consumption. These older units had a 9V power supply or a switchable 9-12V power supply and the power supply had to be set to 9V to run a new pump and the screw terminals need to be free of corrosion and it is a good idea to cut back the wires and verify they are shiny copper and have not corroded or oxidized.