Direct vent combustion air intake connection

What is going on

Connect the intake pipe using the supplied rubber coupling, a plastic coupling or the RF000142 coupling. Support the vent so the rubber elbow carries no load.

Likely causes

• Rubber elbow carrying weight of field-supplied pipe
• Condensation in intake coupling without a drain

Check in this order

1. On upflow units, secure the intake pipe to the air intake coupling with the supplied take-apart rubber coupling or a plastic coupling, or invert the coupling, glue the pipe on and fasten it to the furnace top with screws.
2. On counterflow units, use the rubber coupling and worm gear clamps supplied, so intake piping inside the blower compartment can be removed for service.
3. If the RF000142 coupling is used on the intake, install it with the arrow pointing up. Air moves opposite to the arrow.
4. Give the RF000142 a trapped, free-draining field drain tube to a proper disposal point. Cap the unused drain fitting.
5. A tee in the intake pipe with a trapped, free-draining drain can also catch condensate.
6. Do not let the rubber elbow carry the weight of field vent piping. Support the vent externally.

More furnace guides

• Airflow lower than demanded, furnace runs on low stage when high stage is expected
• Alternate combustion air opening (upflow or horizontal)
• Alternate vent/flue location (upflow or horizontal left)
• Annual inspection checklist
• Auxiliary limit control (location and purpose)
• Auxiliary limit switch open (blower compartment)