If the mid-line of the unit is to be installed at or below the waterline of the
vessel, a Siphon Break must be used. Either a "valve" or "tee"
type can be used.
The valve must always be at least 10" above the waterline, regardless of the
pitch and roll of the vessel. There is no maximum height. Commercially available
anti-siphon valves are fairly reliable; however, they do get fouled and can
stick in either the open or closed position. Regular maintenance is necessary.
The "tee" method is a more reliable type of siphon break. The tee is
generally designed with 1/2" hose barbs on the input and output connections
and a smaller connection on the branch. The branch hole should be restricted to
1/8" dia. Mount the tee a minimum of 10" above the vessel’s waterline.
The branch side of the tee is connected to an overboard thru hull, also mounted
above the waterline. Or, the branch side of the tee can be tapped into the
exhaust hose, after the Silencers. The hose from the branch should always flow
in a continuous up or down direction. Never loop the hose up and down. If in
doubt, call us for consultation. The thru hull should be mounted so it is
always vented to atmosphere, never under water.
