Venting Configurations - Rheem Raypa DELTA 399B Installation And Operation Manual

Venting Configurations

For heaters connected to gas vents or chimneys, vent
installations shall be in accordance with the NFGC
(U.S.), or B149 (Canada), or applicable provisions of
local building codes.
Natural Draft Vertical Venting
(Category I)
Installation
Natural draft venting uses the natural buoyancy of the
heated flue products to create a thermal driving head
that expels the exhaust gases from the flue. The nega-
tive draft must be within the range of -.01 to -.08 in. WC
as measured 12 in. above the appliance flue outlet to
ensure proper operation. Vent material must be listed
by a nationally recognized test agency.
The maximum and minimum venting length for
Cate-gory I appliances shall be determined per the
NFGC (U.S.) or B149 (Canada).
The diameter of vent flue pipe should be sized ac-
cording to the NFGC (U.S.) and B149 (Canada). The
minimum flue pipe diameter for conventional negative
draft venting using double-wall Type B vent is: 6 in. for
Models 399B and 499B, 8 in. for Models 649B, 749B
and 899B, 10 in. for Model 989B, 12 in. for Models
1259B and 1529B, 14 in. for Models 1799B, 1999B
and 2069B, and 16 in. for 2339B.
NOTE: A vent adapter (field-supplied) must be
used to connect Type B vent to the unit.
The connection from the appliance vent to the stack
must be as direct as possible and shall be the same
diameter as, or larger than, the vent outlet. The hori-
zontal breaching of a vent must have an upward slope
of not less than 1/4 inch per linear foot from the heater
to the vent terminal. The horizontal portions of the vent
shall also be supported for the design and weight of
the material employed to maintain clearances and to
prevent physical damage or separation of joints.
28
8' OR LESS
(MODEL 992B)
10' OR LESS
(ALL OTHER MODELS)
CAT I CERTIFIED VENT PIPE
Fig. 26: Natural Draft Vertical Venting
(Category I)
Termination
The vent terminal should be vertical and should termi-
nate outside the building at least 2 ft above the highest
point of the roof that is within 10 ft. The vent cap should
have a minimum clearance of 4 ft horizontally from and
in no case above or below (unless a 4 ft horizontal
distance is maintained) electric meters, gas meters,
regulators and relief equipment. The distance of the
vent terminal from adjacent public walkways, adjacent
buildings, open windows and building openings must
be consistent with the NFGC (U.S.) or B149 (Canada).
Gas vents supported only by flashing and extended
above the roof more than 5 ft should be securely guyed
or braced to withstand snow and wind loads.
Common Venting System
NOTE: When an existing category I appliance is
removed or replaced, the original venting system
may no longer be sized to properly. Improper-
ly sized venting system can cause formation of
condensate, leakage and spillage etc.
ACAUTION: A listed vent cap terminal, ade-
quately sized, must be used to evacuate the flue
products from the heaters.