Venting Requirements for the New Bosch Greentherm T9900 & T9800 Condensing Tankless Water Heaters

Global Protankless Supply is now carrying the New Bosch Greentherm T9900 & T9800 Condensing Tankless Water Heaters.  This is to cover the venting requirements for the indoor model heaters.  The Bosch T9900 & T9800 models can be vented horizontally out the sidewall of the home or vertically through the roof.  The venting connection and intake hole is on top of the unit and is 2" diameter.  The Bosch Greentherm T9900 & T9800 series heaters can be vented using 2", 3" or 4" PVC, CPVC, PP or ABS.  

The minimum exhaust pipe length is 1 ft (0.3m) of straight vent pipe. The minimum air intake pipe length is 1 ft or one 90° elbow or an air intake grill cap to prevent debris from falling into the appliance.

See the table below for maximum exhaust and intake lengths:

Please call Global Protankless Supply at 866-289-4652 for further questions or to place an order.

New Greentherm PP Concentric up and out vent kit

New for the Bosch Greentherm C 950 ES & C 1050 ES is the polypropylene concentric up-and-out venting kit consisting of the appliance adapter, a 90° elbow, and a termination. This is the simplest and quickest venting option possible for a condensing tankless unit. The outer metal pipe and the inner polypropylene pipe make it both lightweight and rigid. The termination is telescopic to allow for varying wall thicknesses.

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)

The Greentherm models C 950 ES & C1050ES are also approved for PP twin-pipe venting systems. Availability of generic PP vent pipe has increased and systems are becoming more popular due to ease of installation.  The twin pipe installation would be used if the customer needed to go out a different area out the sidewall or through the roof and would need to take the combustion air from the outside also.



PP Common Venting Systems for Cascaded Units

New for the Greentherm C 950 ES and C 1050 ES, and the Therm C 1210 ES and C 1210 ESC, is a common venting system of polypropylene pipe for up to four appliances. Offered in either a side by side or back to back configuration, the kits allow for a single vent pipe for all units. Combustion air must be taken from the room for multiple units common vented.  A 3" PVC 90 degree elbow would want to be placed on either the left or right air intake hole for the combustion air to keep anything from falling into the heater.  This is mandatory for commercial applications, with multiple units installed and that the multiple units are common vented with either the side by side or back to back venting option.  All other applications such as residential, single units, etc. must take the combustion air from the outside using 3" PVC or 3" dia PP pipe.  Please refer to the installation manual for the Bosch tankless water heater for the combustion air requirements for the heater. 

Side by side with horizontal termination (left),

back to back with vertical termination (right)



The new polypropylene pipe (PP) common venting system features different kits for cascaded units of 2, 3 or 4 units.  Kits would have to be ordered as needed:

Kit A - side by side, units #1 & #2 (2 heaters) (7736501100)

Kit B - side by side, units #3 & #4 (1 heater) (7736501254)

Kit C - back to back, units #1 & #2 (2 heaters) (7736501253)

Kit D - Extension back to back, units #3 & #4 (2 heaters) (7736501252)

There are also additional 6" diameter PP venting pieces available.  There are additional:

Horizontal Termination Dia 6"  (7736501117)

Vertical Termination Dia 6"  (7736501119)

Extension rigid straight pipe 20" Dia 6"  (7736501137)

Extension rigid straight pipe 40" Dia 6"  (7736501135)

Extension rigid straight pipe 80" Dia 6"  (7736501133)

Rigid 90 degree elbow Dia 6"  (7736501132)

For example:

Say you were common venting and cascading 4 units side by side and venting up through the roof then you would want 1 - Kit A for units #1 & #2, 1 - Kit B for unit #3 and then 1 - Kit B for unit #4.  You would also then need 1 - 90 degree elbow, how many extra feet of extension straight pipe and then the vertical termination.