Direct Vent/Ducted Combustion Air; Optional Air Intake Adapters - Watts AERCO MFC Series Pre-Installation Application Manual

MFC Series Boiler Vent and Combustion Air Guide
If the louver features a proof-of-open switch, it can be connected to the boiler's Enable/Disable
terminals. The Enable/Disable terminals must be closed for the unit to fire. If the proof-of-open
switch does not prove within the programmed time frame, the boiler will shut down.
For wiring connections and further details regarding the auxiliary relay and limit circuit, refer to
the MFC Series boiler Operations and Maintenance manual.
If an AERCO supplied sequencing panel is being used to manage a multiple boiler installation,
the louver can be opened using the System Start relays. Refer to the MFC Series Operations and
Maintenance Manual, GF-148, for wiring connections and further details.

5. Direct Vent/Ducted Combustion Air

The MFC is approved for direct vent installation; i.e., it can draw all combustion air from the
outdoors through a metal or PVC duct connected between the MFC unit(s) and the outdoors. This
configuration is useful for situations in which room air is insufficient or otherwise unsuitable for
combustion. The minimum ducted combustion-air duct sizes for the MFC boilers are as follows:
•
MFC 3000 = 10-inch diameter
•
MFC 4000 = 12-inch diameter
•
MFC5000 = 12-inch diameter
•
MFC 6000 = 14-inch diameter
•
MFC 8000 = 16-inch diameter
•
MFC10000 = 16-inch diameter
In many installations, the combustion air duct can be manifolded for multiple unit applications.
The length and restriction of the ducted combustion duct directly impact the size, length and
restriction of the discharge venting. The direct vent air intake should be located at least 3 feet
below any vent termination within 10 feet.
A screen with mesh size not smaller than 1" x 1" must be installed at the inlet of the ducted
combustion air duct.

5.1 Optional Air Intake Adapters

The following Air Inlet Adapters are available from AERCO:
Air Inlet Adapters
MFC Model
3000 Dual Fuel
NOTE:
Rectangular to circular transition piece shall be field-fabricated.
Adapters for other Riello burners shall be field-fabricated.
TAG-0080_OG • GF-148-V •
Riello Burner Part Number
RLS 120
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