I know the subject of holding tanks
has been discussed many times on this site and I for one was very interested in the input from everyone. After much research
and reading the posts on this and many other sites I was able to design a system that worked for our CSY
44 WO. I wanted a gravity, through tank, system so I could eliminate three way valves, vented loops, etc. The most difficult design feature to overcome was where to install a tank so I could keep hose runs as short as possible and close to vertical to the existing thru hull
. I decided that a bulkhead mounted tank was the only way to achieve this and Ronco had a perfect fit. The tank has a 9 gallon capacity and is 15” X 32” X 5”.
I just completed our install and have to say I am very pleased with the results.
The tank was installed on the aft bulkhead so it partially sat on the upper counter of cabinet and the discharge piping was routed through the cabinet to the thru hull
under the sink. I secured the tank to the bulkhead by constructing a frame and shelf out of 3/4” marine plywood
, glued and screwed together then West System the whole thing. The frame was then thru bolted and screwed to the aft bulkhead. The discharge from the head
runs up the bulkhead next to the door frame to the top of the tank and the 1” vent comes out of the other end and is routed into the upper cabinet then out the side of the hull
is all 1 1/2” schd. 40 PVC from the head
to the tank and tank to thru hull
with the exception of some short pieces of sanitary flexible hose to allow for movement. I installed a Groco 1 1/2” brass valve inside the cabinet and close to the tank as possible that is closed when tank use is required or can be left open for a flow through system when not. Tank venting is supplied by 1” PVC from the tank to a thru hull. I added a valve to the vent line with the thought that in the event of a blockage, the valve could be closed which would pressurize the as the head was flushed in hopes of dislodging any blockages. I don’t know if it would work
and hope I don’t need to find out. Thought it was a good idea to have just in case.
During the first test of the tank, I filled it full with fresh water
to check for leaks
. Then opened the valve to check for leaks
down stream and check the discharge rate. When I opened the valve the tanked emptied in about 5 seconds.
After three weeks of use everything seems to be working very well and I can focus on the fit and finish of a tank cabinet.