Do you have a source for mud dauber or wasp screens for the furnace inlet and outlet vent?
Bill, (Broken Arrow, OK)
Bill, (Broken Arrow, OK)

All mud dauber's nests should be checked for and routinely removed during the annual cleaning of the furnace. The photo exemplifies the importance of annual furnace maintenance, but during the actual operation of the furnace, keep those tubes free from any obstructions! Including those screens commonly found in accessory stores.