Blower question

[ControlThis]

I have a squirell cage blower in a hot air furnace. The blower has various small holes around the housing (pressure side) of the blower. Looks almost like they're for mounting various things to the blower housing. I've seen brand new furnaces with holes like this almost like they are supposed to be there. Will plugging up all these extra holes improve performance or are they truly there for a reason???
Thnaks!

 

[crjones]

They are there so you do not exceed the allowed pressure so the blades do not bend. Plugging will increase the load on the blades and the bearings.