Connect Breeching And Venting Systems - Weil-McLain 94 Series Manual

Boiler manual: • Installation

Connect breeching and venting systems

Seal the venting system gas-tight and connect the breech-
ing with welded seams and joints to prevent leakage of
combustion products into the boiler room. This is most
important for forced draft vent systems. Conventional
flue pipe should not be used as it could leak flue gases
and carbon monoxide emissions through seams and
joints, resulting in severe personal injury or death.
General venting information
1. Model 94 boilers operate with positive overfire pressure. Adjust
damper assembly (see Figure 44, page 35) during burner start-up
to achieve 0.1" W.C. positive pressure at damper sample hole.
Construct metal breeching:
1. 894-2194 boilers — construct "stub" to attach breeching:
a. Use steel breeching-16 ga. or heavier, 20" nominal diameter,
minimum 6-inch length (so damper can open).
b. Unbolt the breeching counter flange from flue collar flange.
c. Insert or butt the breeching stub against counter flange so
stub is square to flange. Stub must not extend past the face of
the flange.
d. Weld stub to flange gas-tight. Use caution when welding to
avoid warping the flange due to excessive heat accumulation.
1
Flue collar flange
2
Counter flange
3
(8) ½" x 1½" machine bolts,
nuts and washers
4
Sealing rope, 3 ⁄ " diameter
8
5 Gas-tight weld to breeching
adapter pipe
6
20-inch diameter breeching
pipe, min. 6" long (by installer)
e. Make sure the sealing rope is intact on the flue collar flange.
f. Attach the flange/stub assembly to the flue collar using ½" x
1½" machine bolts and washers provided. The connection
must be gas-tight.
2. 2294-2594 boilers — attach factory-supplied breeching adapter:
a. The boiler is supplied with a flanged breeching adapter 22-inch
diameter x 12 inches long.
b. Make sure the sealing rope is intact on the flue collar flange.
c. Attach the flange/stub assembly to the flue collar using ½" x
1½" machine bolts and washers provided. The connection
must be gas-tight.
3. See Figure 39 for minimum breeching diameter.
4. Select material type and thickness in compliance with local
codes.
5. Refer to ASHRAE Guide for chimney and breeching calculations
and construction and lining.
Long horizontal breechings, excessive number of tees and
elbows or other obstructions restricting combustion gas
flow can result in possibility of condensation, flue gas
leakage and carbon monoxide emissions, causing severe
personal injury or death.
Part No. 550-110-275/1018
• Start-Up • Maintenance • Parts
Figure 39
Minimum breeching diameter
Boiler AHRI vent or
model liner diameter
(inches)
Balanced Forced
draft draft
(note 4)
894 18 14
(note 1)
994 21 14
(note 1)
1094 21 16
(note 1)
1194 21 16
(note 1)
1294 21 16
(note 1)
1394 24 18
(note 1)
1494 24 18
(note 1)
1594 24 18
(note 1)
1694 24 18
(note 1)
1794 24
(note 1)
1894 27
(note 1)
1994 27
(note 1)
2094 27
(note 1)
2194 27
(note 1)
2294 27
(note 2)
2394 30
(note 2)
2494 30
(note 2)
2594 30
(note 2)
Note 1 Boiler is supplied with a counter flange that must
be welded to a 20-inch diameter x 6-inch minimum
length adapter. The breeching can then be reduced or
increased to the size listed above.
Note 2 Boiler is supplied with a flanged adapter, 22-inch
diameter, for connection to 22-inch diameter
breeching. Breeching size can be increased after the
adapter if required for the application.
Note 3 Forced draft — Boiler, breeching and stub vent
operate at positive pressure. Entire system must be
gas-tight to prevent leaks. Stub vent height must be
limited to prevent negative draft with 3-foot minimum
stub vent height above roof, 15-foot minimum overall
height. See Figure 41 and Figure 42.
Note 4
Balanced draft — Boiler operates with positive
pressure overfire. Chimney may provide excess draft
which may require a barometric draft control installed
and set to provide minimum draft to maintain 0.1"
positive pressure at flue collar. Minimum chimney
height above roof is 3 feet. Minimum overall height is
20 feet. For other vent heights, use ASHRAE Guide for
sizing. See Figure 40 and Figure 42.
Boiler
flue collar
dimensions
(inches)
(note 3)
20 round, flanged
(note 1)
20 round, flanged
(note 1)
20 round, flanged
(note 1)
20 round, flanged
(note 1)
20 round, flanged
(note 1)
20 round, flanged
(note 1)
20 round, flanged
(note 1)
20 round, flanged
(note 1)
20 round, flanged
(note 1)
20 20 round, flanged
20 20 round, flanged
20 20 round, flanged
20 20 round, flanged
20 20 round, flanged
20 round, flanged
22
(note 2)
20 round, flanged
22
(note 2)
20 round, flanged
22
(note 2)
20 round, flanged
22
(note 2)
31