
Originally Posted by
jstenger
Moombadaze,
You need to add a spring loaded check valve and a tee in the hose between the hard tank and the IBS. The flow direction of the check valve would have to face the tee. There is no need to attach a hose to the other side of the valve, it is only used to bring air into the hard tank. Once the IBS is sucked flat, the vacuum pressure will cause the check valve to open and allow air to enter the hard tank, and allow all the water to be drained out. Leave the oneway vent where it is, and don't bother adding a directional valve. This way it will be fully automatic.
Note: It must be a spring loaded check valve.