MACH
®
Gas Fired Boiler
17
1. A stainless steel vent adapter is required to mate the boiler exhaust connection and the vent pipe. See the table
below for the applicable part numbers.
2. A normally-closed motorized damper is required on the boiler’s air intake. See the table below for the applicable
part numbers.
3. The draft, measured inside the vent at the rear of the boiler,
must not exceed -0.04” W.C.
Excessive negative
draft will cause nuisance trips such as flame failures.
4.
The vent system must be properly drained of condensate before returning to the boiler. Please see Section
3.5.3.6 for information on installing condensate drains in the exhaust vent.
Table of Required Stainless Steel Vent Adapters and Category II Motorized Dampers
The normally-closed motorized damper operates on 120 VAC and features an end limit switch wired into the boiler’s
external interlock circuit. Upon a call for heat, the boiler’s damper relay will energize and drive the damper open.
Once the damper reaches the fully-open position, the end limit switch makes contact and closes the external interlock
circuit allowing the boiler to fire. The diagram below shows the wiring necessary to install the normally-closed
motorized damper.
Boiler Size
Nominal
Stack Size
Stainless Vent
Adapter
Normally-Closed
Motorized Damper
A
B
C
D
C750
6"
2620000181 (OEM)
1004906943
6”
6”
9”
1.38”
C900
8"
2620000366
1004906944
8”
8”
11” 2.38”
C1050
8"
2620000366
1004906944
8”
8”
11” 2.38”
