Smith Cast Iron Boilers Series 28A User Manual
Page 5
Page 5
SERIES 28A BOILER INSTALLATION AND OPERATION INSTRUCTIONS
Chimney Inspection & Sizing
If this boiler will be connected to a masonry chimney, a
thorough inspection of the chimney must be performed.
Ensure that the chimney is clean, properly constructed,
lined and properly sized, see Figure 2. Table 2 lists the
equivalent breeching and flue sizes required for the 28A
boilers.
Table 2 - Equivalent Breeching & Chimney Size
Boiler Model
Breeching Size
Chimney Size
in
mm
in
mm
28A-4
10
254
10
254
28A-5
10
254
10
254
28A-6
10
254
10
254
28A-7
12
305
12
305
28A-8
12
305
12
305
28A-9
14
356
14
356
28A-10
14
356
14
356
28A-11
14
356
14
356
28A-12
14
356
14
356
28A-13
14
356
14
356
28A-14
16
406
16
406
28A-15
16
406
16
406
28A-16
16
406
16
406
28A-17
18
406
18
406
28A-18
18
457
18
457
Note: These sizes are based on a 20 foot chimney height.
Figure 2 - Vertical Venting
The 28A is designed for pressurized operation with a
back pressure of 0.10 in,
2.54 mm W.C. before the
smoke hood slide damper. If the vent configuration
results in a back pressure greater than this, the burner
capacity may have to be verified. Contact the Smith
Technical Service Department to verify the burner
capacity.
The chimney must be able to provide 0.10" WC at the
boiler outlet. If the chimney is 50 ft. or taller it may
produce excessive draft (approx. - 0.25" WC) and a
barometric draft regulator may be needed.
When more than one appliance is connected to the
same chimney flue the flue must be large enough to
safely vent the combined output of all the appliances.
WARNING: If an appliance using any type of
a mechanical draft system operating under
positive pressure is connected to a chimney
flue, never connect a Category I appliance to
this flue. Doing so can result in the
accumulation of carbon monoxide which can
cause severe personal injury or death!