Concentric ventilation system for Rinnai tankless water heatersRinnai's unique Ubbink concentric venting system offers maximum performance and safety while still being easy to install. Compatible with all indoor Rinnai water heaters, except the 98 series which uses separate intake and exhaust venting. Aluminum Inner Vent For Exhaust • Lightweight Available concentric water heater vent fittingsRinnai® is a registered trademark of Rinnai Corporation. GadgetsGo is not associated with or sponsored by Rinnai Corporation. |