John Wood JW375T75N-AV, Instruction Manual

Page: 15 / 36

15
If the water heater is being installed as a replacement for an existing
heater in pre-existing venting, a thorough inspection of existing venting
system must be performed prior to any installation work.
VENT DAMPERS - Any vent damper, whether it is operated thermally
or otherwise must be removed if its use inhibits proper drafting of the
water heater.
Thermally Operated Vent Dampers: this gas-fired water heater has
a thermal efficiency at or above 80% which may produce a relatively
low flue gas temperature. Such temperatures may not be high enough
to properly open thermally operated vent dampers. This would cause
spillage of the flue gases and may cause carbon monoxide poisoning.
Vent dampers must bear evidence of certification as complying with
the current edition of the American National Standard ANSI Z21.66
CGA 6.14 (covering electrically and mechanically actuated vent
dampers). Before installation of any vent damper, consult the local
gas utility for further information.
To insure proper venting of this gas-fired water heater, the correct
vent pipe diameter must be utilized. Any additions or deletions of
other gas appliances on a common vent with this water heater may
adversely affect the operation of the water heater. Consult your gas
supplier if any such changes are planned.
For proper venting in certain installations, a larger diameter vent
pipe may be necessary. Consult your gas supplier to aid you in
determining the proper venting for your water heater from the vent
tables in the current edition of the National Fuel Gas Code ANSI
Z223.1/NFPA 54 or the Natural Gas and Propane Installation Code
CAN\CSA B 149.1.
Periodically check the venting system for signs of obstruction or
deterioration and replace if needed.
The combustion and ventilation air flow must not be obstructed.
The water heater with draft hood installed must be connected to a
chimney or listed vent pipe system, which terminates to the outdoors.
Never operate the water heater unless it is vented to the outdoors
and has adequate air supply to avoid risks of improper operation,
explosion or asphyxiation.
• For proper draft hood attachment, the draft hood legs may be
angled slightly inward.
• Place the draft hood legs in the receiving holes on the top of the
water heater. The legs will snap in the holes to give a tight fit.
Secure draft hood with the supplied brackets.
• Place the vent pipe over the draft hood. With the vent pipe in position,
drill a small hole through both the vent pipe and draft hood. Secure
them together with a sheet metal screw. See Figure 13.
Obstructed or deteriorated vent systems may present serious health
risk or asphyxiation.
FIGURE 13.
The vent pipe from the water heater must be no less than the
diameter of the draft hood outlet on the water heater and must
slope upward at least 1/4 inch per linear foot (21 mm per meter).
See Figure 14.
All vent gases must be completely vented to the outdoors of the
structure (dwelling). Install only the draft hood provided with the
new water heater and no other draft hood.
Vent pipes must be secured at each joint with sheet metal screws.
FIGURE 14.
There must be a minimum of 6” (153 mm) clearance between single
wall vent pipe and any combustible material. Fill and seal any
clearance between single wall vent pipe and combustible material
with mortar mix, cement, or other noncombustible substance. For
other than single wall, follow vent pipe manufacturer’s clearance
specifications. To insure a tight fit of the vent pipe in a brick chimney,
seal around the vent pipe with mortar mix cement.
Failure to have required clearances between vent piping and
combustible material will result in a fire hazard.
Be sure vent pipe is properly connected to prevent escape of
dangerous flue gases which could cause deadly asphyxiation.
Chemical vapor corrosion of the flue and vent system may occur
if air for combustion contains certain chemical vapors. Spray can
propellants, cleaning solvents, refrigerator and air conditioner
refrigerants, swimming pool chemicals, calcium and sodium
chloride, waxes, bleach and process chemicals are typical
compounds which are potentially corrosive.