12
VENTING SYSTEM INSPECTION & INSTALLATION
An unlined chimney will have leaks that will cause
poor chimney performance (NO DRAFT), and could
result in poor positive pressure in the combustion
chamber.
Horizontal portions of the venting system should
not exceed 10 feet in length. Horizontal lengths
over 10 feet will have a negative effect on the
chimney performance.
The chimney should extend at least 2 feet above
any portion of the building within 10 feet. See
figure 5 at right. It should produce a negative draft
of .06 to .08 inches of water column, (W.C.), as
measured with a draft gauge between the boiler
and barometric draft control while maintaining an
.02 inch W.C. negative draft in the combustion
chamber. See chart below for recommended
chimney or vent sizes.
Inadequate draft will cause improper combustion,
resulting in dirty flue ways and high fuel bills.
When installing a single boiler, connect the flue
pipe with the same size
as the boiler outlet to the
chimney, sloping upward
continuously toward the
chimney approximately ¼”
per foot. Bolt or screw joints
together to avoid sag.
If an oil fired water heater
is vented into the same
flue as the boiler, provide
a separate hole into the
chimney whenever pos-
sible. When this isn’t pos-
sible, use a “Y” connection
in the flue pipe, using a
separate draft regulator for
each unit. When a chimney
will not provide adequate
draft to handle the input
from the water heater and
boiler simultaneously, wire
the units so that only one will operate at a time,
favoring the water heater.
CHIMNEY OR VENT SIZES
MODEL NO.
DIA. OF
CHIMNEY
OPENING
(BREECHING)
CHIMNEY SIZE
(IN. X IN. X FT.)
FLUE
OUTLET
SIZE
SFM6225W
8
8X8X15
8”
SFM7275W
9
8X12X15
8”
SFM24150W
9
8X12X15
6”
SFM25175W
9
8X12X20
7”
SFM25200W
9
8X12X20
7”
SFM26225W
9
8X12X20
8”
SFM27275W
10
12X16X15
8”
SFM36225W
12
12X16X15
8”
SFM37275W
14
12X16X20
8”
SFM47275W
14
12X16X15
8”
SFM57275W
18
16X20X20
8”
SFM67275W
18
20X20X15
8”
SFM77275W
22
20X24X15
8”
SFM87275W
22
20X24X20
8”
TYpical VenTing of 2 or More uniTs
figure #6
Summary of Contents for SFM24150W
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