High efficiency furnace exterior pvc vent screens

Any verbiage on requirements for vent screens? Manufacturer recommendations?

Thanks in advance.

A combustion air intake must be provided
with an elbow opening downward. The screen
provided with the furnace must be installed in the
elbow to prevent entry of debris or creatures.

I have found it best to use only 1 inch hardware cloth cut and pressed into the fittings.

Plastic drain plugs have too much restriction on venting and intake. This causes improper combustion and high levels of CO production. One manufacturer provides these drain plugs and I have encountered more combustion problems with that make than any other.