Overflow Kit issues

[mnwakerider]

So I just put in an overflow kit in my 2003 SAN. I am having an issue with it. When I am filling the bags off of the vent line I am getting a fair amount of flow out of the drain line. I tested plugging the drain and the system worked perfectly. It does not flow out of the drain unless I am filling.

Any ideas on why the drain line is letting water out while filling the extra bags? I have done other kits that use the Jabsco pumps, but have never done a kit when the aerator style pumps. Any help is greatly appreciated.

[Texan1554]

Bunch of threads around here on this. Do some searches and you will find the info you are looking for. Search piggy back ballast, ballast installs etc...

Has to do with the older design of the system, most folks just plugg the overflows while filling in that system I believe.