Part number 550-100-268/1220
2
CONDENSING
GAS
BOILER
—
V
ENT
A
DDENDUM
- continued
• Stack / Vent Flow Rate for each individual boiler model is listed in the table below. This fl ow rate is
based on the unit running at 9.25% CO
2
and the maximum fl ue gas temperature of 210°F.
The values can vary depending on the location of the installation and operating conditions.
• A carbon monoxide detector(s) is required in the boiler room for
Evergreen
boilers installed in a
Category II confi guration. The carbon monoxide detector must be wired on the same electrical
circuit as the boiler. Check your local codes for any additional requirements of carbon monoxide
detectors.
I
mproper Installation of a Category II vent system resulting in positive pressure in the vent system can
result in fl ue gas spillage and carbon monoxide emissions, causing severe personal injury or death.
Weil-McLain recommends the use of a Variable Speed Chimney Fan/ Power venter to ensure that the
appropriate negative pressure is maintained for Category II venting. This is recommended because, as a
result of the boiler’s effi ciency, the exhaust gas temperatures can be quite low resulting in less natural draft.
A fl ow proving switch should be wired into the Proof of Closure jumper circuit on the boiler control. See
the boiler manual for additional information. The use of this device should be considered in any Engi-
neered Vent system.
Weil-McLain recommends the use of a Double Acting Barometric Damper or Modulating Damper to en-
sure the appropriate negative pressure range is kept for Category II venting. The use of this device should
be considered in any Engineered Vent system.
When using a damper of any kind, it is recommended to use a thermal spill switch to detect any exhaust
fl ow into the boiler room. Verify the temperature range on the thermal spill switch is adequate for the Flue
gas temperature from the
Evergreen
boiler. The use and set-point of this shall be determined by the sys-
tem designer. The Auto reset input on the Boiler’s control can be used to wire in the thermal spill switch.
Increasing the negative pressure in the vent pipe will slightly increase the fi ring rate at low fi re, thus reduc-
ing the boiler’s true modulation range. Consider this factor during system design.
Code Compliance
Venting / Combustion air piping – Installations must provide provisions for combustion and
ventilation air in accordance with the section “Venting of Equipment”, of the National Fuel Gas Code,
ANSI Z223.1 / NFPA 54, or “Venting Systems and Air Supply for appliances” of the Natural Gas and
Propane Installation Code, CAN/CSA B149.1, or applicable provisions of the local building codes.
See
Evergreen
boiler manual for approved vent material.
TABLE 1
Rating & Vent Data
Boiler
Model
Input
Btuh
Stack / Vent
fl ow rate
scfm
Negative Pressure to be
maintained at
Vent Connection of the boiler
Inches w.c.
Evergreen
Vent
Adapter
required for
Category II
EVG 220
220,000
61
-0.001 to -0.100
6”
EVG 299
299,000
83
-0.001 to -0.100
6”
EVG 300
300,000
83
-0.001 to -0.100
6”
EVG 399
399,000
111
-0.001 to -0.100
6”
