Field Wiring Connection
Venting
General
Appliance Categories
Heaters are divided into four categories based on the
pressure produced in the exhaust and the likelihood of
condensate production in the vent.
Category I
– A heater which operates with a non-pos-
itive vent static pressure and with a vent gas
temperature that avoids excessive condensate pro-
duction in the vent.
Category II
– A heater which operates with a non-pos-
itive vent static pressure and with a vent gas
temperature that may cause excessive condensate
production in the vent.
Category III
– A heater which operates with a positive
vent pressure and with a vent gas temperature that
avoids excessive condensate production in the vent.
Category IV
– A heater which operates with a positive
vent pressure and with a vent gas temperature that
may cause excessive condensate production in the
vent.
See Table J for appliance category requirements.
Use only the special gas vent pipes listed for use with
Category IV gas burning heaters, such as the AL29-4C
stainless steel vents offered by Heat Fab Inc. (800-
772-0739), Protech System, Inc. (800-766-3473),
Z-Flex (800-654-5600) or American Metal Products
(800-423-4270). Pipe joints must be positively sealed.
Follow the vent manufacturer’s installation instructions
carefully.
Support of Vent Stack
The weight of the vent stack or chimney must not rest
on the heater vent connection. Support must be pro-
vided in compliance with applicable codes. The vent
should also be installed to maintain proper clearances
CAUTION:
Label all wires prior to disconnection
when servicing controls. Wiring errors can cause im-
proper and dangerous operation. Verify proper
operation after servicing.
Fig. 22: Rear Wiring Location
DANGER: SHOCK HAZARD
CAUTION:
Proper installation of flue venting is
critical for the safe and efficient operation of the
heater.
NOTE:
For additional information on appliance
categorization, see appropriate ANSI Z21 Standard
and the NFGC (U.S.), or B149 (Canada), or
applicable provisions of local building codes.
WARNING:
Contact the manufacturer of the vent
material if there is any question about the appliance
categorization and suitability of a vent material for
application on a Category III or IV vent system.
Using improper venting materials can result in
personal injury, death or property damage.
NOTE:
A grounding electrode conductor shall be
used to connect the equipment grounding
conductors, the equipment enclosures, and the
grounded service conductor to the grounding
electrode.
CAUTION:
Condensate drains for the vent piping
are required for installations of the XTherm. Follow
vent manufacturer instructions for installation and
location of condensate drains in the vent.
Condensate drain trap must be primed with water to
prevent gas flue leak and must be routed to an
appropriate container for neutralization before dis-
posal, as required by local codes.
Make sure electrical power to the heater is discon-
nected to avoid potential serious injury or damage to
components.
California Hot Water Supply, Inc.
(800) 249-7244
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