Fulton Edge ICX or FB-F Vertical Tubeless Boilers (Steam), Gas Fired - Manual (Page 48)

41-G 1/01
Description/Instructions
Exhaust Side Wall Venting (UL and
MEA Approved- MEA File Number
68-79-E Vol. 2 )
a) Boilers for which sidewall venting
may be utilized are No. 2 oil, natural
gas, or combination No. 2 oil and nat-
ural gas,sizes 4 to 30 H.P. The fol-
lowing criteria is required for installa-
tions using sidewall venting:
1) Flue vent piping shall be pitched
upward at 1/4" per foot of length.
2) A U.L. Approved draft fan must be
installed to provide sufficient draft
(-.02 to -.04 inches WC pressure -
0.508 to -1.016 mm) to safely vent
the products of combustion.
3) The draft fan should be located as
close to the flue outlet as possible.
4) Draft regulation sufficient to
lower the draft to between -.02 and
-.04 inch WC pressure (-.508 to -
1.016mm) may be required. The
draft regulator(s) must be between
the boiler and draft fan.
5) The draft fan shall have an air flow
proving switch wired in series with the
boiler air safety switch.
6) The sidewall vent total length from
boiler exhaust to termination shall not
exceed 35 feet (10.7 m) with 4
elbows maximum.
Combustion Air Intake (UL and
MEA Approved- MEA File Number
68-74-E Vol. 3 )
a) Vertical boilers as described in
MEA 68-79-E Vol. 3 applied with
combustion air intake assembly. This
shall be applicable only to gas fired
units, sizes 4-30 boiler horsepower.
The following criteria is required for
installations using combustion air
intake assemblies.
1) Outside air intake inlet shall be
equipped with a vent cap in order to
prevent flame blow out from exces-
sive wind. This vent cap shall have a
minimum cross sectional opening
equal to an 8 inch vent pipe.
2) All intake ducting shall have a
cross sectional area equal to or
greater than 50 square inches.
3) A mesh screen shall be affixed to
the air inlet with openings of approxi-
mately 1/2" x 3/4".
4) The total length from outdoors
to the boiler intake shall not exceed
35 feet (10.7 m) with four elbows
maximum.
Corrosion of flue pipe
a) In the case of a combustion flue
pipe, acid may develop over a long
period of time by the following
process. Chlorine containing gases,
such as halocarbon refrigerants, car-
bon tetrachloride, trichloroethylene,
or perchloroethylene, when drawn
into combustion air are broken down
into elemental chlorine gas which
exits up the flue pipe. If the flue pipe
is cold, as it would be if the combus-
tion process had been off for some
time, the water vapor condenses in
the flue pipe during the first few min-
utes of ignition and the chlorine in the
combustion gas dissolves in the
water forming hydrochloric acid. As
the combustion system flue line
increases in temperature, the water
vapor no longer condenses because
the flue temperature is above the dew
point of the combustion gas.
The combustion gas then dries
out (dehydrates) the hydrochloric
acid solution leaving behind dry
chloride salt.
b) When the next cold start-up
occurs, the process repeats except
that more and more chloride collects
and concentrates along the flue. As
the quantity of chloride increases it
does not dehydrate completely as the
flue heats up and a corrosive poultice
develops which attacks the steel and
will also attack the boiler.
c) Concentration levels of only a
few ppm of chlorine containing
compounds in combustion air can
produce serious corrosion over long
periods of time. High chlorine con-
taining compounds such as carbon
tetrachloride or perchloroethylene
would be prime suspects .
Air Flow
Safety Switch
U.L. Approved
Induced Draft Fan
Side Wall
Vent
Termination
(By Others)
Side Wall Vent
(By Others)