chimney or vent?

[retire09]

For the termination of a vent serving both a natural gas water heater and a unit heater in a garage, do you use the requirements for a chimney G2427.5.3 or a vent G2427.6.3?

 

[JBI]

What are they installing? A listed vent or a listed chimney?

CHIMNEY. A primarily vertical structure containing one or more flues, for the purpose of carrying gaseous products of combustion and air from an appliance to the outside atmosphere.

Factory-built chimney. A listed and labeled chimney composed of factory-made components, assembled in the field in accordance with manufacturer’s instructions and the conditions of the listing. Masonry chimney. A field-constructed VENT. A pipe or other conduit composed of factory-made components, containing a passageway for conveying combustion products and air to the atmosphere, listed and labeled for use with a specific type or class of appliance.

Special gas vent. A vent listed and labeled for use with listed Category II, III and IV gas appliances. Type B vent. A vent listed and labeled for use with appliances with draft hoods and other Category I appliances that are listed for use with Type B vents. Type BW vent. A vent listed and labeled for use with wall furnaces. Type L vent. A vent listed and labeled for use with

appliances that are listed for use with Type L or Type B vents. chimney composed of solid masonry units, bricks, stones or concrete.

 

[klarenbeek]

You might want to check the instructions on the unit heater to see if it can be vented with another appliance. Most of the new ones I see need to be vented independently.

As far as the cap, agree with JBI. If using chimney, follow chimney section, if using gas vent such as b vent use gas vent section.