[C320-list] Dometic Masterflush 7120 Installation

[Troy Dunn]

Was a pretty crummy day yesterday so I decided to follow in Doug Treff's
footsteps and install the Masterflush 7120 on Wonky Dog.

We never flush with bay water and after 4 years of using the shower hose to
flush the toilet and sitting on a bowl that was uncomfortably small; I
decided enough with all that and replaced the old Jabsco.

I posted a whole bunch of pics in my gallery.

Couple of additional notes beyond all the great ones Doug already provided
a couple years back.

1) The macerator outlet leaves the head in a direction that is suboptimal.
It will be a tight turn either left or right to get to an existing hole in
the liner.   There are essentially 2 solutions to the problem.   You must
either install a 90 degree PVC elbow before the joker or after.   I opted
to install the joker after the turn.  I will provide an update if this
becomes a problem.

2) The obvious place to pull power and ground is from the wires going to
the shower drain sump.   I intended to piggy back off the switch spade for
power and grab ground at the pump.   Turns out the mini switch for my sump
has mini spades.   I didn't have piggy backs that would work for that
spade...so... I cut the macerator (the one that we never will use) wires
right at their butt connection and extended those newly available wires.
I tied positive to the new switch pigtail and I connected negative to the
solenoid spade and then piggybacked the head macerator to that spade.  I
guess if I sell the boat I should hook the holding tank macerator back
up...I'll add that to my product backlog.  Although....I'd prefer to rip
out that macerator and install a raw water washdown pump to connect to my
newly available  thru hull barb under the head.  Getting all that
Chesapeake mud off the anchor would be kinda nice, LOL.

3) I opted to use WhaleX to hookup the freshwater.   This was incredibly
simple.  Razor blade at the head sink cold water line.   Cut out an inch,
install a T.  Buy a 1/2” to WhaleX 90 degree adapter.   Install line.

4) Something to watch out for.   The template sent to me with the head was
improperly sized for the switch.  This would have been a disaster.
Fortunately I purchased the second optional switch and noticed the issue
when making my paper template with my copier.  I was measuring to make sure
the copier wasn’t messing up the scale and I was glad I did.  Fortunately a
proper template was provided with the optional switch so I just used that
one.   No idea how the other one got messed up.

Troy Dunn
Hull #514