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Holding tank monitor

I had the electrosense monitor, but it failed. The Cat5 wire was not outdoor type, and in the bilge it cracked and shorted out. I otherwise really like the monitor, it worked well and was trouble free until that happened. Electrosense is now out of business.

I bought a scad monitor and the internal tank sensor. Nice idea, with a pipe that is inserted into that tank, with foil strips inside, instead of having foil strips on the side of the tank like many monitors use.


Trouble is, I am struggling to get it to calibrate. After cutting the sensor to the correct length, I tested it in a bucket and it seemed fine. But in the actual tank I am getting a calibration error. At this point I don't have confidence that it will be trouble free, and since there is no way to know how full the tank is to properly calibrate it, I've spit water out the vent, and still can't get it to work.

Anyway, other than the no longer available electrosense, what are others using? There seem to be very few options, short of cutting a bigger hole in the top of the tank for a standard 5 hole SAE mounted type.
 

Brian_Burk

New Member
My wife and I are new owners of a 1978 Morgan 382 (SV Samba) and are also looking for drop in option for the holding tank sensor. Electrosense seemed to the be consensus until late. I too am interested in hearing what folks have found to work a without modifying the original plug.

@Warren Holybee - Is the SCAD sensor you linked a drop in replacement to the original plug?
 
My wife and I are new owners of a 1978 Morgan 382 (SV Samba) and are also looking for drop in option for the holding tank sensor. Electrosense seemed to the be consensus until late. I too am interested in hearing what folks have found to work a without modifying the original plug.

@Warren Holybee - Is the SCAD sensor you linked a drop in replacement to the original plug?
Very close. The SCAD is 1" NPT, so only a 1" to 1.25" NPT adapter is needed. The sensor can be cut to length.

I think I have it working at least "good enough" but need to fill and empty the tank a few times to be more comfortable. Calibrating it in a bucket doesn't work. It works fine in the bucket, but in the tank gives a calibration error. What I did (which wasn't fun) was remove the sensor and leave the tank open. Empty the tank. Put the sensor in and do the empty calibration, then remove it and fill the tank, looking in the hole to not over fill it. Then put the sensor in and do the full calibration.

Now, it seems there is about 1/4 to 1/3 tank before the gauge reads any more than empty, but it did seem to read full at the correct time. As long as I know I am getting close to full, and when it is completely full I consider that "good enough" It is possible I cut the sensor a bit short.

But given how difficult it was I need to test it some more before I am comfortable with it. I will try and do that this next weekend. If it proves to work, I would have to recommend this as the best option for our difficult tank situation.
 

Brian_Burk

New Member
Thanks, Warren.

Out of curiosity, how did you wire the new sensor? Did you split power off an existing circuit in the head? I am thinking how best to do it and tying into the existing shower pump circuit doesn't seem too hard. I might be able to get power out of the existing holding tank sensor which is currently dead. But I am not sure where it is dead, a multi meter would be able to solve that quickly.
 
I mounted the meter near my electrical panel. It is powered directly off that panel through an inline fuse. Then 3 wires go from the meter to the sensor. If I mounted it in the head, I would do it the same way, and run new wire from the panel to the head. It's not a hard run. There is conduit from the locker under the chart table through the settee to the locker across from the head. From there there is a passage to the mast bucket, and then up into the head cabinet. You would need to pull 5 wires, 2 for power, and 3 for the sensor, which instead of going to the panel would exit the conduit and go down into the bilge.
 

terry_thatcher

Terence Thatcher
I have been afraid to take the old sensor out for fear I would break something never get the hole covered up. Plus with a 6' draft, my bilge floor is waaayyy down there.
 
I have been afraid to take the old sensor out for fear I would break something never get the hole covered up. Plus with a 6' draft, my bilge floor is waaayyy down there.
For sure, buy a 1.25 npt plug and have it in your other hand. Get the plug in ASAP to hold the smell where it belongs. It came out pretty easy with a set of channel locks, and seals well only being screwed in hand tight. You could probably fabricate a very long "socket" with a piece of pipe.

If you use the holding tank with any regularity, you really need more than a light that turns on only after it's so full you can no longer use it.
 
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