5.4 Boiler Venting – Side-wall or Direct Vent Systems Sizing Tables & Vent Safety Device
•
All venting lengths must be calculated to equivalent lengths,
all application must include at least one 90° elbow
•
Venting must be a type ‘BH” [AL294C® material]
•
Maximum vent length [equivalent] = 30 ft. [9m]
•
Minimum vent length [equivalent] 5 ft. [1.5m]
•
Maximum number of 90° elbows = 2 or 3 45° elbows, each
90° e bow is equivalent to 10 ft. or straight pipe, the 45°
elbow is equivalent = 5 ft.
•
Condensate TEE must be provided [equivalent length = 7 ft.]
•
Appliance reducing adapter [equivalent length 3 ft.]
•
Sealed combustion, combustion air intake sizing, must be
sized according to the burner manufacturers instructions
•
Vent [breeching] pressure shall not exceed 0.20 inches w.c.
[0.50 mbar]
•
Vent termination must be a TEE type, follow warning
regarding termination locations. Do not include the
termination TEE length in the vent length calculation.
•
Venting shall be sloped, so any condensation developed will
drain through the condensate TEE fitting
•
Vent safety device, differential air pressure switch [manual
reset] NC switch opens on rise of pressure.
•
Optional function of power burners which can employ an
post purge function to exhaust flue gases for a fixed time [1
minute to 4 minutes maximum]
•
Burner employing a standby air damper closed position, the
closed position should be slightly opened to allow hot flue
gases to escape upward through venting and not be
entrapped in the combustion head. Important note, that in
negative building pressures, the observation and odor of flue
gases may enter the boiler room.
Determining vent length [equivalent] Example:
Appliance reducing adapter
[x1] = 3 ft.
Condensate TEE
[x1] = 7 ft.
12” vent straight vent pipe
[x3] = 3 ft.
E bow 90°
[x1] = 10 ft.
Termination TEE
[x1] = 0 ft.
Length [equivalent] =
23 ft.
GT 210 A Series
Model
Boiler
Connection
ø
Oil-Gas
Vent ø
[
∆
p] Pressure switch
Setting [inches w.c.]
GT 214 A
6 inch
4 inch
GT 215 A
6 inch
4 inch
GT 216 A
7 inch
5 inch
GT 217 A
7 inch
5 inch
GT 218 A
7 inch
5 inch
Set Switch @ 150%
above gas burner gas
manifold or oil burner
head pressure
Venting
31
