MACH
®
Gas Fired Boiler
16
E. When a duct is used to meet the requirement for combustion air supply, as described in paragraphs A through D,
above, the opening of the duct shall be located so there is no possibility of cold air affecting steam or water piping,
electrical equipment or mechanical equipment.
F. When combustion air is supplied by mechanical means, an airflow-sensing device must be installed. It must be
wired into the pre-ignition limit string to prevent the burner from starting or to stop an operating burner in case of
air supply failure.
G. When all combustion air is supplied through a make-up air heater, and the appliance is interlocked to the heater,
the requirements of paragraphs A through F do not apply.
NOTICE!
1. The free area of a combustion air supply opening is calculated by deducting the blockage area of any fixed
louvers, grilles or screens from the total area of the opening.
2. Screens shall be not smaller than ¼”
3. Motorized louvers shall be interlocked with the appliance so that they are proven open prior to main burner
ignition and operation
Table of Canadian Minimum Area of Combustion and Ventilation Air Openings
MACH
®
Boiler
Required Combustion Air
Opening
Ventilation Air Opening
Model #
Input (Btu/Hr)
in
2
mm
2
in
2
mm
2
C750
750,000
25
16,129
10
6,452
C900
900,000
30
19,355
10
6,452
C1050
1,050,000
35
22,581
10
6,452
3.5.3 Flue Venting
This boiler is not certified for use with Type "B" vent nor with PVC venting.
3.5.3.1
VENT SIZING
The vent must be sized in accordance with the ASHRAE Systems and Equipment handbook, Chapter 30 or according
to the vent manufacturer’s recommendations. When using manufactured venting systems, consult your vent supplier
for correct sizing and structural support requirements.
Table of Vent Design Parameters
MACH
®
Boiler
Model
Frictional
Resistance
Stack
Temperature
CO
2
Natural Gas
CO
2
LP Gas
C750 – C1050
0.22”
210°F
9.0%
10.4%
3.5.3.2
CATEGORY II INSTALLATIONS
The MACH C750, C900 and C1050 are dual-certified for both Category II and Category IV operation. Category II
appliances operate with a non-positive vent static pressure and with a vent temperature that may cause excessive
condensate production in the vent. There are several requirements for reliable operation of the boilers under
Category II conditions:
All boiler venting systems should be designed by a qualified venting
professional experienced in venting system design. The information contained herein should
be used as a guide only and is not intended to be used in lieu of qualified technical expertise.