This new PP concentric up and out vent kit is approved for the New Green Therm C950ES & C1050ES tankless water heaters. The PP concentric up and out vent kit is also approved for the Bosch Therm C950ES & C1050ES.
Before attaching the appliance adapter to the top of the heater, a second metal plate comes with the kit and would cover the other intake air hole. Then you would want to remove the exhaust collar from the top middle of the heater and then attach the appliance adapter as this will enable the heater to exhaust to the outside and also take its combustion air down the outer side of the same hole.
Bosch Greentherm PP concentric up and out vent kit (7738003210)