What To Consider Before Purchasing A Propane Tankless
Water Heater - Combustion Air Requirements
The combustion air requirements only apply to indoor
installations and where air is drawn from within the room where
the water heater is installed. The 250SX, 2400E are the
only Bosch tankless water heaters that have a separate air
intake that allows for air to be drawn from the outside. The RTG-53DV GT-199DV RTG-74DV are the only Rheem tankless water heaters that allow for air to be drawn from the outside. For all other indoor
installations, the amount of combustion air should be a minimum
volume of 50 cubic feet per 1,000 Btu/hr rated input.
If the gas water heater is installed in an area smaller than what the combustion
call for, then the installer must make special provisions for combustion air in
the form of two openings, each one within 12" of the top and 12" of the bottom
of the space, having a total free area of 1 square inch per 1,000 Btu/hr of
rated input if the air is taken from inside the house. This requirement reduces
to 1 square inch per 4,000 Btu/hr if the air is taken from the outside.
Model
Combustion Air Requirements in Sealed Room
Size of openings if cannot meet combustion air
requirements in
sealed room
Combustion air requirements do not
apply to the 2400E/250SX when air is drawn from the outside
through the intake vent.
RTG-74PV
199,900
10,000
1,250
50 sq inches (i.e. 7” x 7”)
200 sq inches
(i.e. 14” x 14”)
RTG-74DV,
RTG-74X, GT-199DV
199,900
Combustion air requirements do not apply to
the RTG-74DV and GT-199DV when air is drawn from the outside
through the intake vent.
Note: A Propane tankless water heater cannot be installed in a mobile home, bedroom, bathroom, or any other confined living space normally kept closed.
Note: The above information is meant as guidance.
Always consult your installation manual and/or local code
requirements before any actual installation.
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