The Bosch Therm 940ES and Bosch Therm 830ES tankless water heaters require either 3" or 4" single wall stainless steel venting.
The Bosch Therm 940ES is a 199,000 BTU heater and the Bosch Therm 830ES is a 175,000 BTU heater. Read the manual carefully as these two heaters have been approved for longer runs using 4" Z-Flex stainless steel venting.
At Pro Water Heater Supply we carry the full line up of Z-Flex Z-Vent 3" and 4" stainless steel vent pipe. This special single wall venting is rated AL29-4C and is approved for Category I (vertical only), II, III & IV applications and is designed for use with boilers, high efficiency gas and oil heaters and water heaters where cool flue gases are vented under pressure.
Z-Vent contains a built-in, fail-safe gasket and locking band connection. No sealant is required.
Z-Vent is available in up to 24" diameter and is also used to vent boilers.
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