"Demand" is a very harsh word!
Besides, one of the grey tanks (usually the kitchen) has an undercounter air relief valve and doesn't need a rooftop vent. Basic plumbing theory.
Formerly posting as "littleblackdog"
Martha, Allen, & Blackjack
2006 Chevy 3500 D/A LB SRW, RVND 7710
Previously: 2008 Titanium 30E35SA. Currently no trailer due to age & mobility problems. Very sad!
"Real Jeeps have round headlights"
