Section 27-886. Special venting arrangements

(a)  Equipment with sealed
  combustion chambers. The vent requirements contained in this  subchapter
  do  not  apply  to equipment having sealed combustion chambers and which
  are so constructed and installed that all air for combustion is  derived
  from outside the space being heated and all flue gases are discharged by
  integral  vent to the outdoors. Such equipment, having integral venting,
  shall be installed in accordance with the conditions of  the  applicable
  standard governing their use.
    (b)  Gas-vent  exhausters  and chimney exhausters. Gas-vent exhausters
  and chimney exhausters may be  used  with  gas  appliances  in  lieu  of
  natural  draft  vents.  Where  an  exhauster  is  used  with gas-burning
  equipment requiring venting, provisions shall be  made  to  prevent  the
  flow  of  gas  to the main burner in the event of failure of the exhaust
  system. A vent connector serving gas equipment vented by  natural  draft
  shall not be connected into the discharge side of a power exhauster.
    (c)  Ventilating  hoods  and  exhaust  systems.  Ventilating hoods and
  exhaust  systems  may  be  used  to  vent  gas  equipment  installed  in
  commercial  applications. When automatically operated equipment, such as
  water heaters,  are  vented  through  natural-draft  ventilating  hoods,
  dampers  shall  not  be  installed  in  the ventilating system. When the
  ventilating hood or exhaust  system  is  equipped  with  a  power-driven
  exhaust  fan, the equipment control system shall be so interlocked as to
  permit equipment operation only when the power exhaust is in  operation.
  When  used, ventilating hoods shall be built and installed in accordance
  with the provisions of subchapter thirteen of this chapter.