indoor tankless gas water heaters must be vented vertically or horizontally to the outdoors using Category III stainless steel venting material (No other venting material is permitted). RTG-42PV indoor models require 3" stainless steel venting. RTG-74PV and GT-199PV indoor models require 4" stainless steel venting. Venting details, including clearances and diagrams, can be found in the "Use & Care Manual" of Rheem indoor tankless water heaters. NOTE: Rheem outdoor tankless water heaters do not require venting materials.When choosing an indoor location, you should consider the shortest venting distance to the outdoors. Consult your professional installer or contact us for maximum venting distances.Rheem offers all necessary venting materials, accessories and expertise to make your tankless water heater installation easy - including horizontal vent kits listed below.Vent Kits for Horizontal VentingRheem horizontal vent kit (RTG20003) for RTG-42PV series indoor gas models includes:(1) Adapter (2) 90 degree elbows (1) 12" length vent pipe (1) Two-piece 6" - 19" adjustable length pipe (1) Two-piece horizontal wall thimble (1) 90 degree termination elbow with vent screen (1) Pressure relief valve Rheem horizontal vent kit (RTG20007) for RTG-74PV and GT-199PV series indoor gas models includes:(1) Adapter (2) 90 degree elbows (1) 12" length vent pipe (1) Two-piece 6" - 19" adjustable length pipe (1) Two-piece horizontal wall thimble (1) 90 degree termination elbow with vent screen (1) Pressure relief valve 18-AWG, 2-conductor thermostat wire for remote control Rheem horizontal vent kit (RTG20066 ) for RTG-53DV series indoor gas models includes:(1) Adapter (1) 90 degree elbows (1) Horizontal termination (1) 12" length vent pipe (1) Pressure relief valve (1) 18-AWG, 2 conductor thermostat wire for remote control The location of your indoor tankless water heater may require additional venting material. Venting diagrams shown are for illustrative purposes only.
