John Wood Takagi - 910 - Manual (Page 7)

7
Combustion Air Supply
The water heater location must provide enough air for proper
combustion and ventilation of the surrounding area. See the
latest edition of ANSI Standard Z223.1 or any applicable
local codes. In general, these requirements specify that if
the unit is installed in a confined space, there must be a
permanent air supply opening.
Minimum Recommended Air Supply Opening
Size For Water Heater
Water
heater
size
When drawing
make-up air from
outside the
building
When drawing
make-up air from
inside the building
(from other
rooms within)
MAX
380,000
BTU/h
164cm 2 (25.3 in 2 ) 2452cm 2 (380 in 2 )
When combustion air
is supplied from out-
side the building, an
opening communicat-
ing directly with the
outside should have
a minimum free area
of 6.5cm
2 (1 in 2 ) per
15,000 BTUH input
of the total input rat-
ing of water heater in
the enclosed area
When combustion
air is supplied from
inside the building,
an opening com-
municating with the
rest of the dwell-
ing should have a
minimum free area
of 6.5cm
2 (1 in 2 ) per
1,000 BTUH input of
the total input rating
of water heater in the
enclosed area. This
opening should never
be less than 1284cm
2
(199 in 2 )
Combustible Air Supplied By Mechanical Fan Or
Make Up Air Device
The 910 water heater is equipped with a combustible air
sensor that will shut off the unit when inadequate combus-
tible air supply to unit is detected.
If a mechanical fan or make up air device is used to
supply air to the water heater or utility room, the installer
should make sure it does not create drafts which could
cause nuisance shutdowns.
If a blower is necessary to provide adequate combustion
air to the water heater, the blower and water heater must
be set up so that the water heater cannot fire unless the
blower is operating. Possible methods include the use
of the 910 internal fan control port or the use of external
flow sensors/transmitters and relays. •
•
Direct Intake Vent System
This 910 water heater may be converted to a direct-vent
(sealed combustion) appliance by installing an adapter (Part
No. TM-DV50) which will bring all required combustible air
from outside the building. When installing the direct-vent
conversion kit, please follow all instructions included with
the kit.
The 910 must be installed in a location where the proper
amount of combustible air will be available to it at all
times without obstructions.
If used as a direct-vent appliance, the 910 requires a
127mm (5 in.) combustible air supply pipe. The intake
pipe must be sealed airtight.
Air supply pipe can be made of ABS, PVC, galvanized
steel, corrugated aluminum, corrugated stainless steel or
Category III stainless steel.
Change the DIPswitch settings to the direct-vent system
(see diagram below).
Sidewall venting is recommended for the direct-vent
system.
The manufacturer recommends running the exhaust vent
and the intake pipe parallel.
Upper bank of
DIPswitches
Lower bank of
DIPswitches
7-Seg LED
Make sure power to the unit is turned OFF
before changing the DIPswitch settings.
The dark square is the direction the
DIPswitch should be set to.
•
•
•
•
•
•
ON
MST P-ALARM OUT DIRE MODE TMP3 TMP2 TMP1
8 7 6 5 4 3 2 1
Lower bank of
DIPswitches (Detail)
ON
MST P-ALARM OUT DIRE MODE TMP3 TMP2 TMP1
8 7 6 5 4 3 2 1
Lower bank of
DIPswitches (Detail)