User Guide
32
B. CHIMNEY CONNECTOR
1. A chimney connector (vent pipe) is used to connect the
boiler to the base of the chimney. The chimney connector
should be kept as short as possible. The horizontal length
of the chimney connector shall not be greater than 10 feet.
NOTE: Secure chimney connector to cast iron smokebox
collar with three (3) #10 x ½" self drilling hex head TEK
screws provided in miscellaneous parts carton. Locate
screws around perimeter of connector as shown in Figure
15 and approximately ½" in from edge. Use drill with
5/16" hex bit to drive screws through connector and
smokebox collar.
DANGER
The chimney and connector shall be inspected
annually for signs of debris and corrosion. Loose
mortar at the base of the chimney may be a sign
of condensate damage to the chimney. A chimney
professional shall be contacted immediately to
examine the damage and recommend a solution.
Long term operation while in this condition may
cause a venting failure and force ue gases into the
living space. If the chimney is to be re-lined use the
recommendations in NFPA 31, Appendix E or CSA
B139.
2. Vent Connector shall be any of the following and of the
same size as the outlet of boiler.
a. Type L or a factory built chimney material that
complies with the Type HT requirements of ANSI/
UL 103. Install in accordance with listing and
manufacturer’s instructions.
b. Steel pipe having resistance to corrosion and
heat with a minimum wall thickness of 24 Gauge
(0.024”).
DANGER
Any signs of condensate seepage at the base of
the chimney shall be inspected immediately. The
discoloration may be a sign of chimney damage and
must be remedied immediately.
C. DRAFT
1. The natural draft generated through a chimney is dependent
on several factors including, chimney height, temperature
of ue gases, cross section area of chimney, chimney
wall insulation value, dilution air and total volume of
ue gases, to name a few. Make sure that the boiler has
been running for at least 5 minutes before measuring the
draft.
2. Minimum Draft at Breech (Canopy) – The draft induced
by a chimney must create at least a pressure of 0 (zero)
inches water column (“ w.c.) at the pressure tapping on
the canopy mounted on rear of boiler (see Figure 17).
The pressure at the canopy cannot be positive since this
could create a condition that allows ue gas by-products
to escape from the draft regulator. A negative pressure
reading up to -.03 inches water column is acceptable for
proper operation. (See Tables 15A thru 15C and 16)
Burner Specications at the rear of this manual for more
details)
3. Minimum Overre Pressure – The overre pressure is
another piece of information that is often measured,
however this should be done for observation purposes
only! The breech pressure must be used to qualify the
draft condition. See Tables 15A thru 15C and 16 for
more details as a guide. Actual draft and temperature
measurements may be different then those values in the
table.
D. STACK TEMPERATURE
1. The temperature of the ue gases has a signicant effect
on the amount of draft created in a vertical chimney as
well as the propensity to create condensate. The higher
the stack temperature, the greater the amount of draft
that can be generated. A lower stack temperature not
only reduces the amount of draft that can be created but
it also increases the possibility that the ue gases could
condense in the chimney connector or stack.
2. NFPA 31 and CSA B139 have information to help the
installer make an appropriate choice of venting materials.
In some cases a chimney may have to be lined to create
sufcient draft. In other cases, the chimney may have to
be lined to prevent the corrosion of a masonry chimney.
Consult with a chimney specialist knowledgeable on the
requirements for chimney requirements in your area.
Figure 17: Smokebox Pressure Tapping
for Checking Draft at Breech
V. NATURAL DRAFT VENTING (continued)