I'd try it. Make something that slips on with screen and rubber bands, so
you can pull them off later if needed. The official answer I've heard is not
to screen or cover. Cause the humid exhaust freezes on screens, and blocks
the exhaust.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
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wrote in message
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Got my new furnace with air yesterday and got wondering, should there
be any screens over the air in or exhaust out lines.

my combustion air in is just a stub of a pipe going in, the exhaust
has a elbow pointing down.

when cutting grass today I saw a wasp checking out the pipes, and got
concerned a nest of something unpleasant could move in