VacuFlush Holding Tank

[TommyB]

Hi All,
have 3 vacuflush toilets plumbed into a center line holding tank. Appox 85 gals give or take.
Just realized yesterday that the red lights in the heads are not working . they are supposed to warn on 3/4 tank full.

Question is, how do I test the sender unit on the tank. Looks to be a 1/4 to 1/2" nipple with a piece of copper tubing, then 2 wire are attached to the copper tubing.
(I'll post pics later)
No idea make / model etc of the sending unit.

Thanks!

 

[Jim saco]

Blow into the sending unit and see if the light comes on. The puck rots out because it's mild steel. Or the sending tube is rotten inside the tank. I replaced the puck with a pneumatic bilge pump switch and it's been working ever since.

 

[Finalee]

The float is likely hung up with some @#$#@

 

[Beckytek]

Take off the rubber top off the red hockey puck, short out the 2 wires connected and see if the red light comes on, it may be burned out. There are a number of things that could be wrong as mentioned as being mis-adjusted. The adjustment is in the red housing with the springs. Tubes could be rusted through, etc.
Here is a diagram of the system so you can see how it works.

 

[TommyB]

Looks like I spoke to soon. Looking at the top of my holding tank, what I thought was a sending unit is just some copper vent tube, hooked to a 1/4" plastic tubing then runs through a bulkhead and ends up over the shower sump

not sure where the sending unit is. Only one holding tank that 3 heads flow to.

Copper tubing runs to plastic tubing


top of holding tank
Inlet
pump out
Air vent (to carbon filter)
then that 1/4" air vent copper thing

 

[Finalee]

It must be accessed via another hatch. I do not see it in the pic.

 

[TommyB]

It must be accessed via another hatch. I do not see it in the pic.

no other hatch any where near that holding tank.
the only other way to get in there would be to cut a hole in the sole.
I've checked

 

[Jim saco]

Follow the wires backwards starting at the 3/4 full light. Mine was in my forward sump bildge mounted on the wall. If you have the vital/owners manual it'll tell you were it is or was mounted.

 

[TommyB]

Follow the wires backwards starting at the 3/4 full light. Mine was in my forward sump bildge mounted on the wall. If you have the vital/owners manual it'll tell you were it is or was mounted.

Thanks.
So it works off air pressure like that switch thing Beckytek posted about?
I saw that red hockey puck looking thing but thought it was a high water alarm in the forward bildge area.
I'll check it out and post what I find.
Again Thanks!!

 

[MikeP]

I believe that "vent tube" your seeing IS the tube to the sensor that triggers the 3/4 light. The sensor is, as previously explained, a hockey puck-shaped thingie that may or may NOT be particularly close to the tank fittings.

The dip tube on the tank that provides the air pressure to the sensor is s essentially just a a copper pipe (1/2" or 3/4", I can't remember) with a hole in the top for the 1/4" copper tubing-to the sensor. The length of the dip tube determines the point at which the light illuminates. If the dip tube or copper tubing to the sensor has any leaks, the light will not illuminate.

Obvioulsly, as noted, there could be an electrical issue rather than a tubing issue but the original dip tubes are often perforated after years of waste immersion...

You can replace an original copper dip pipe with a PVC tube/appropriate fitting.

 

[TommyB]

I believe that "vent tube" your seeing IS the tube to the sensor that triggers the 3/4 light. The sensor is, as previously explained, a hockey puck-shaped thingie that may or may NOT be particularly close to the tank fittings.

The dip tube on the tank that provides the air pressure to the sensor is s essentially just a a copper pipe (1/2" or 3/4", I can't remember) with a hole in the top for the 1/4" copper tubing-to the sensor. The length of the dip tube determines the point at which the light illuminates. If the dip tube or copper tubing to the sensor has any leaks, the light will not illuminate.

Obvioulsly, as noted, there could be an electrical issue rather than a tubing issue but the original dip tubes are often perforated after years of waste immersion...

You can replace an original copper dip pipe with a PVC tube/appropriate fitting.

Thanks!
Located the Hydro-Par hockey puck thing.
Shorted out the 2 wires and lights come on. So guessing the pick-up tube is wasted.
Now, if I can get that 1/2 fitting off the top of the tank.
Can I heat this plug or is that a bad idea? I had both feet pressing on a big arsed cresent wrench and the plug would not move
Almost like that plug is welded in place.

Ordered a new sending unit and plug with tube from sams. Now to get the plug out

 

[TommyB]

Obvioulsly, as noted, there could be an electrical issue rather than a tubing issue but the original dip tubes are often perforated after years of waste immersion...

You can replace an original copper dip pipe with a PVC tube/appropriate fitting.

Finally got the nut holding that cooper tube off. Only thing left was the nut. guess the entire tube got eaten away. Replaced with a new nut/ welded copper tube.
All seems to work
Again Thanks!

 

[marmac520]

TommyB re your picture of the top of the holding tank - what is the device beside the tank in lower right of the pic?

 

[magnawake]

Finally got the nut holding that cooper tube off. Only thing left was the nut. guess the entire tube got eaten away. Replaced with a new nut/ welded copper tube.
All seems to work
Again Thanks!

So how did you finally get the nut to break free? Mine is stuck as well. I wasnt going to order a new unit until I could get the nut loose.

 

[jlangley]

I like to use a 50/50 mixture of transmission fluid and acetone myself. You have to shake it up well before each use as they separate while sitting, but a very effective penetrant.

 

[Boatsb]

Acetone is pretty dangerous in enclosed spaces. Quite the flammable liquid with a low boiling g point so it evaporates quickly. It also is a solvent for plastics. Be careful how and where you use it.

 

[fissioneng]

So how did you finally get the nut to break free? Mine is stuck as well. I wasnt going to order a new unit until I could get the nut loose.

Wire brush the paint/corrosion away from the threads, then soak with PB Blaster, leave overnight, repeat. Then gently tap each flat of the head. I need to do this too, but that's how I would approach it. If it doesn't loosen one weekend, I let it sit a week and go at it again.

PB Blaster is pretty flammable too, but you don't need much.

 

[TommyB]

TommyB re your picture of the top of the holding tank - what is the device beside the tank in lower right of the pic?

a valve.
This model did not come with and overboard pump out. So I added a T into the deck pump out,
then this valve, and ran hose to a vacuflush pump-out motor to a through hull.
I'm sure not the best way, but works
Was not sure the pressures involved, so added the valve before the vacuflush motor just in case i needed to close that part of the line off.
Now that I know it will work as intended, I'll remove the valve and run a length of hose right to pump out motor

I used pb-blaster on it for a couple days and it came right off.

 

[TommyB]

So how did you finally get the nut to break free? Mine is stuck as well. I wasnt going to order a new unit until I could get the nut loose.

PB Blaster, soaked for 2 days.
Socket and breaker bar and it came right off.
Ordered new plug with the copper tube brazed on it from sams.