Holding tank fittings

[brettportzer]

So, we have a 1972 43DC that has the three tanks built into the keel, and the only one that has ever been plumbed is the middle one, for freshwater.

Both heads are now vacuflush and they both connect to a completely dead old treatment system up in the bow.

My aim is to remove all of that and move the plumbing to the front holding tank, which also is in the bow, about 2 ft away, so it should be a reasonably easy changeover.

I have read a bunch of threads on here about these issues, but they all have involved fixing the tube when it rotted off, pretty much, but I don't have anything plumbed to this tank.

Got the plugs out, but I don't know how to plumb in the dip tube, for instance...

Any ideas? Attaching a pic of the plate and the plugs.

Thanks!!

 

[Top Hatt Craig]

That’s a water tank flange you have pictured. The largest fitting is for a water level gauge and one each of the smaller are for fill and vent with the fourth unused. A holding tank flange looks like this.

 

[Top Hatt Craig]

The two large holes are for the dip tube and the level sensor, the next smaller is from toilets and the smallest is for vent. The dip tube can be replaced with PVC use a “close nipple” then you can glue 1 1/2” PVC inside the close nipple as it’s a slip fit. The 1 1/2” “T” is then threaded onto the close nipple. Trial fit before gluing so you can position and mark the dip tube so it’s about 3/4” off the bottom of your tank.

 

[TROUBLE]

Do you have the Pump out access on your deck?
Art

 

[brettportzer]

Thanks for this info.

So basically you are saying that the holes are the wrong size and I need to change the plate?

I have gotten the impression from other threads that removing the plate is tough.

 

[brettportzer]

Do you have the Pump out access on your deck?
Art

We do, there are some T's in the setup for going into or out of the treatment/holding tank, but basically the way it is currently being used is as a holding tank where both heads come together into a PVC pipe and then there is a hose that goes to the treatment tank and then it either goes out through a seacock or up to the deck.

The vent is also functioning correctly as well.

 

[Top Hatt Craig]

Thanks for this info.So basically you are saying that the holes are the wrong size and I need to change the plate?I have gotten the impression from other threads that removing the plate is tough.

You might be able to fabricate a PCV level sensor that doesn’t need as large of a hole as the original.

 

[brettportzer]

You might be able to fabricate a PCV level sensor that doesn’t need as large of a hole as the original.

I'll have to investigate further, but it looks like maybe the large hole in my plate can be the dip tube, the next one down can be the toilet input and then another the vent, and then I could use the dometic tank full sensor (Dometic DTM01 https://www.defender.com/product.jsp?id=1759985 ) and mount that directly through the fiberglass top of the tank.