Is your motorhome or caravan unusually long (> 6.5-metre-long interior) or are the living areas separated by doors? If so, we recommend installing an additional gas sensor. Another sensor means that any propane/butane gases or narcotic gases that escape can be detected much more quickly; the control panel would trigger the alarm long before a critical gas concentration could occur. You can connect up to three sensors to the G.A.S.-pro.